--- /dev/null
+.TH IPTABLES-XML 8 "Jul 16, 2007" "" ""
+.\"
+.\" Man page written by Sam Liddicott <azez@ufomechanic.net>
+.\" It is based on the iptables-save man page.
+.\"
+.\" This program is free software; you can redistribute it and/or modify
+.\" it under the terms of the GNU General Public License as published by
+.\" the Free Software Foundation; either version 2 of the License, or
+.\" (at your option) any later version.
+.\"
+.\" This program is distributed in the hope that it will be useful,
+.\" but WITHOUT ANY WARRANTY; without even the implied warranty of
+.\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+.\" GNU General Public License for more details.
+.\"
+.\" You should have received a copy of the GNU General Public License
+.\" along with this program; if not, write to the Free Software
+.\" Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+.\"
+.\"
+.SH NAME
+iptables-xml \(em Convert iptables-save format to XML
+.SH SYNOPSIS
+\fBiptables\-xml\fP [\fB\-c\fP] [\fB\-v\fP]
+.SH DESCRIPTION
+.PP
+.B iptables-xml
+is used to convert the output of iptables-save into an easily manipulatable
+XML format to STDOUT. Use I/O-redirection provided by your shell to write to
+a file.
+.TP
+\fB\-c\fR, \fB\-\-combine\fR
+combine consecutive rules with the same matches but different targets. iptables
+does not currently support more than one target per match, so this simulates
+that by collecting the targets from consecutive iptables rules into one action
+tag, but only when the rule matches are identical. Terminating actions like
+RETURN, DROP, ACCEPT and QUEUE are not combined with subsequent targets.
+.TP
+\fB\-v\fR, \fB\-\-verbose\fR
+Output xml comments containing the iptables line from which the XML is derived
+
+.PP
+iptables-xml does a mechanistic conversion to a very expressive xml
+format; the only semantic considerations are for \-g and \-j targets in
+order to discriminate between <call> <goto> and <nane-of-target> as it
+helps xml processing scripts if they can tell the difference between a
+target like SNAT and another chain.
+
+Some sample output is:
+
+<iptables-rules>
+ <table name="mangle">
+ <chain name="PREROUTING" policy="ACCEPT" packet-count="63436"
+byte-count="7137573">
+ <rule>
+ <conditions>
+ <match>
+ <p>tcp</p>
+ </match>
+ <tcp>
+ <sport>8443</sport>
+ </tcp>
+ </conditions>
+ <actions>
+ <call>
+ <check_ip/>
+ </call>
+ <ACCEPT/>
+ </actions>
+ </rule>
+ </chain>
+ </table>
+</iptables-rules>
+
+.PP
+Conversion from XML to iptables-save format may be done using the
+iptables.xslt script and xsltproc, or a custom program using
+libxsltproc or similar; in this fashion:
+
+xsltproc iptables.xslt my-iptables.xml | iptables-restore
+
+.SH BUGS
+None known as of iptables-1.3.7 release
+.SH AUTHOR
+Sam Liddicott <azez@ufomechanic.net>
+.SH SEE ALSO
+\fBiptables\-save\fP(8), \fBiptables\-restore\fP(8), \fBiptables\fP(8)
.TH IPQ_CREATE_HANDLE 3 "16 October 2001" "Linux iptables 1.2" "Linux Programmer's Manual"
.\"
-\" $Id: ipq_create_handle.3,v 1.3 2001/11/24 15:09:20 jamesm Exp $
-.\"
.\" Copyright (c) 2000-2001 Netfilter Core Team
.\"
.\" This program is free software; you can redistribute it and/or modify
.\"
.\"
.SH NAME
-ipq_create_handle, ipq_destroy_handle - create and destroy libipq handles.
+ipq_create_handle, ipq_destroy_handle \(em create and destroy libipq handles.
.SH SYNOPSIS
.B #include <linux/netfilter.h>
.br
The
.I protocol
parameter is used to specify the protocol of the packets to be queued.
-Valid values are PF_INET for IPv4 and PF_INET6 for IPv6. Currently,
+Valid values are NFPROTO_IPV4 for IPv4 and NFPROTO_IPV6 for IPv6. Currently,
only one protocol may be queued at a time for a handle.
.PP
The
.B ipq_destroy_handle
returns zero.
.br
-On failure, -1 is returned.
+On failure, \-1 is returned.
.SH ERRORS
On failure, a descriptive error message will be available
via the
--- /dev/null
+.so man3/ipq_create_handle.3
.TH IPQ_ERRSTR 3 "16 October 2001" "Linux iptables 1.2" "Linux Programmer's Manual"
.\"
-.\" $Id: ipq_errstr.3,v 1.2 2001/10/16 14:41:02 jamesm Exp $
-.\"
.\" Copyright (c) 2000 Netfilter Core Team
.\"
.\" This program is free software; you can redistribute it and/or modify
.\"
.\"
.SH NAME
-ipq_errstr, ipq_perror - libipq error handling routines
+ipq_errstr, ipq_perror \(em libipq error handling routines
.SH SYNOPSIS
.B #include <linux/netfilter.h>
.br
--- /dev/null
+.so man3/ipq_message_type.3
--- /dev/null
+.so man3/ipq_message_type.3
.TH IPQ_MESSAGE_TYPE 3 "16 October 2001" "Linux iptables 1.2" "Linux Programmer's Manual"
.\"
-.\" $Id: ipq_message_type.3,v 1.2 2001/10/16 14:41:02 jamesm Exp $
-.\"
.\" Copyright (c) 2000-2001 Netfilter Core Team
.\"
.\" This program is free software; you can redistribute it and/or modify
.\"
.\"
.SH NAME
-ipq_message_type, ipq_get_packet, ipq_getmsgerr - query queue messages
+ipq_message_type, ipq_get_packet, ipq_getmsgerr \(em query queue messages
.SH SYNOPSIS
.B #include <linux/netfilter.h>
.br
--- /dev/null
+.so man3/ipq_errstr.3
.TH IPQ_READ 3 "16 October 2001" "Linux iptables 1.2" "Linux Programmer's Manual"
.\"
-.\" $Id: ipq_read.3,v 1.3 2001/10/16 16:58:25 jamesm Exp $
-.\"
.\" Copyright (c) 2000-2001 Netfilter Core Team
.\"
.\" This program is free software; you can redistribute it and/or modify
.\"
.\"
.SH NAME
-ipq_read - read queue messages from ip_queue and read into supplied buffer
+ipq_read \(em read queue messages from ip_queue and read into supplied buffer
.SH SYNOPSIS
.B #include <linux/netfilter.h>
.br
.BR ipq_get_msgerr
functions to access the queue message in the buffer.
.SH RETURN VALUE
-On failure, -1 is returned.
+On failure, \-1 is returned.
.br
On success, a non-zero positive value is returned when no timeout
value is specified.
.TH IPQ_SET_MODE 3 "16 October 2001" "Linux iptables 1.2" "Linux Programmer's Manual"
.\"
-.\" $Id: ipq_set_mode.3,v 1.2 2001/10/16 14:41:02 jamesm Exp $
-.\"
.\" Copyright (c) 2000-2001 Netfilter Core Team
.\"
.\" This program is free software; you can redistribute it and/or modify
.\"
.\"
.SH NAME
-ipq_set_mode - set the ip_queue queuing mode
+ipq_set_mode \(em set the ip_queue queuing mode
.SH SYNOPSIS
.B #include <linux/netfilter.h>
.br
the ip_queue module does not know that a userspace application is ready to
communicate until it receives a message such as this.
.SH RETURN VALUE
-On failure, -1 is returned.
+On failure, \-1 is returned.
.br
On success, a non-zero positive value is returned.
.SH ERRORS
.TH IPQ_SET_VERDICT 3 "16 October 2001" "Linux iptables 1.2" "Linux Programmer's Manual"
.\"
-.\" $Id: ipq_set_verdict.3,v 1.2 2001/10/16 14:41:02 jamesm Exp $
-.\"
.\" Copyright (c) 2000-2001 Netfilter Core Team
.\"
.\" This program is free software; you can redistribute it and/or modify
.\"
.\"
.SH NAME
-ipq_set_verdict - issue verdict and optionally modified packet to kernel
+ipq_set_verdict \(em issue verdict and optionally modified packet to kernel
.SH SYNOPSIS
.B #include <linux/netfilter.h>
.br
.TP
.B NF_DROP
Drop the packet.
+.TP
+\fBNF_QUEUE\fP
+Requeue the packet.
+.PP
+\fBNF_STOLEN\fP and \fBNF_REPEAT\fP are kernel-internal constants and should
+not be used from userspace as their exact side effects have not been
+investigated.
.PP
The
.I data_len
The application is responsible for recalculating any packet checksums
when modifying packets.
.SH RETURN VALUE
-On failure, -1 is returned.
+On failure, \-1 is returned.
.br
On success, a non-zero positive value is returned.
.SH ERRORS
.TH LIBIPQ 3 "16 October 2001" "Linux iptables 1.2" "Linux Programmer's Manual"
.\"
-.\" $Id: libipq.3,v 1.5 2001/11/24 15:09:20 jamesm Exp $
-.\"
.\" Copyright (c) 2000-2001 Netfilter Core Team
.\"
.\" This program is free software; you can redistribute it and/or modify
.\"
.\"
.SH NAME
-libipq \- iptables userspace packet queuing library.
+libipq \(em iptables userspace packet queuing library.
.SH SYNOPSIS
.B #include <linux/netfilter.h>
.br
running the following commands:
.PP
# modprobe iptable_filter
-.br
+.br
# modprobe ip_queue
-.br
- # iptables -A OUTPUT -p icmp -j QUEUE
+.br
+ # iptables \-A OUTPUT \-p icmp \-j QUEUE
.PP
will cause any locally generated ICMP packets (e.g. ping output) to
be sent to the ip_queue module, which will then attempt to deliver the
unsigned char buf[BUFSIZE];
struct ipq_handle *h;
- h = ipq_create_handle(0, PF_INET);
+ h = ipq_create_handle(0, NFPROTO_IPV4);
if (!h)
die(h);
.\"
.\"
.SH NAME
-ip6tables-restore \- Restore IPv6 Tables
+ip6tables-restore \(em Restore IPv6 Tables
.SH SYNOPSIS
-.BR "ip6tables-restore " "[-c] [-n]"
-.br
+\fBip6tables\-restore\fP [\fB\-c\fP] [\fB\-n\fP]
.SH DESCRIPTION
.PP
.B ip6tables-restore
.TP
\fB\-n\fR, \fB\-\-noflush\fR
don't flush the previous contents of the table. If not specified,
+.TP
+\fB\-T\fP, \fB\-\-table\fP \fIname\fP
+Restore only the named table even if the input stream contains other ones.
.B ip6tables-restore
flushes (deletes) all previous contents of the respective IPv6 Table.
.SH BUGS
.br
Andras Kis-Szabo <kisza@sch.bme.hu>
.SH SEE ALSO
-.BR ip6tables-save "(8), " ip6tables "(8) "
+\fBip6tables\-save\fP(8), \fBip6tables\fP(8)
.PP
The iptables-HOWTO, which details more iptables usage, the NAT-HOWTO,
which details NAT, and the netfilter-hacking-HOWTO which details the
.\"
.\"
.SH NAME
-ip6tables-save \- Save IPv6 Tables
+ip6tables-save \(em dump iptables rules to stdout
.SH SYNOPSIS
-.BR "ip6tables-save " "[-c] [-t table]"
-.br
+\fBip6tables\-save\fP [\fB\-M\fP \fImodprobe\fP] [\fB\-c\fP]
+[\fB\-t\fP \fItable\fP
.SH DESCRIPTION
.PP
.B ip6tables-save
is used to dump the contents of an IPv6 Table in easily parseable format
to STDOUT. Use I/O-redirection provided by your shell to write to a file.
.TP
+\fB\-M\fP \fImodprobe_program\fP
+Specify the path to the modprobe program. By default, iptables-save will
+inspect /proc/sys/kernel/modprobe to determine the executable's path.
+.TP
\fB\-c\fR, \fB\-\-counters\fR
include the current values of all packet and byte counters in the output
.TP
-\fB\-t\fR, \fB\-\-table\fR \fBtablename\fR
+\fB\-t\fR, \fB\-\-table\fR \fItablename\fP
restrict output to only one table. If not specified, output includes all
available tables.
.SH BUGS
.br
Andras Kis-Szabo <kisza@sch.bme.hu>
.SH SEE ALSO
-.BR ip6tables-restore "(8), " ip6tables "(8) "
+\fBip6tables\-restore\fP(8), \fBip6tables\fP(8)
.PP
The iptables-HOWTO, which details more iptables usage, the NAT-HOWTO,
which details NAT, and the netfilter-hacking-HOWTO which details the
-.TH IP6TABLES 8 "Mar 09, 2002" "" ""
+.TH IP6TABLES 8 "" "iptables 1.4.13" "iptables 1.4.13"
.\"
.\" Man page written by Andras Kis-Szabo <kisza@sch.bme.hu>
.\" It is based on iptables man page.
.\"
.\"
.SH NAME
-ip6tables \- IPv6 packet filter administration
+ip6tables \(em IPv6 packet filter administration
.SH SYNOPSIS
-.BR "ip6tables [-t table] -[AD] " "chain rule-specification [options]"
-.br
-.BR "ip6tables [-t table] -I " "chain [rulenum] rule-specification [options]"
-.br
-.BR "ip6tables [-t table] -R " "chain rulenum rule-specification [options]"
-.br
-.BR "ip6tables [-t table] -D " "chain rulenum [options]"
-.br
-.BR "ip6tables [-t table] -[LFZ] " "[chain] [options]"
-.br
-.BR "ip6tables [-t table] -N " "chain"
-.br
-.BR "ip6tables [-t table] -X " "[chain]"
-.br
-.BR "ip6tables [-t table] -P " "chain target [options]"
-.br
-.BR "ip6tables [-t table] -E " "old-chain-name new-chain-name"
+\fBip6tables\fP [\fB\-t\fP \fItable\fP] {\fB\-A\fP|\fB\-C\fP|\fB\-D\fP}
+\fIchain rule-specification\fP [\fIoptions...\fP]
+.PP
+\fBip6tables\fP [\fB\-t\fP \fItable\fP] \fB\-I\fP \fIchain\fP [\fIrulenum\fP]
+\fIrule-specification\fP [\fIoptions...\fP]
+.PP
+\fBip6tables\fP [\fB\-t\fP \fItable\fP] \fB\-R\fP \fIchain rulenum
+rule-specification\fP [\fIoptions...\fP]
+.PP
+\fBip6tables\fP [\fB\-t\fP \fItable\fP] \fB\-D\fP \fIchain rulenum\fP
+[\fIoptions...\fP]
+.PP
+\fBip6tables\fP [\fB\-t\fP \fItable\fP] \fB\-S\fP [\fIchain\fP [\fIrulenum\fP]]
+.PP
+\fBip6tables\fP [\fB\-t\fP \fItable\fP] {\fB\-F\fP|\fB\-L\fP|\fB\-Z\fP}
+[\fIchain\fP [\fIrulenum\fP]] [\fIoptions...\fP]
+.PP
+\fBip6tables\fP [\fB\-t\fP \fItable\fP] \fB\-N\fP \fIchain\fP
+.PP
+\fBip6tables\fP [\fB\-t\fP \fItable\fP] \fB\-X\fP [\fIchain\fP]
+.PP
+\fBip6tables\fP [\fB\-t\fP \fItable\fP] \fB\-P\fP \fIchain target\fP
+[\fIoptions...\fP]
+.PP
+\fBip6tables\fP [\fB\-t\fP \fItable\fP] \fB\-E\fP \fIold-chain-name new-chain-name\fP
.SH DESCRIPTION
-.B Ip6tables
-is used to set up, maintain, and inspect the tables of IPv6 packet
+\fBIp6tables\fP is used to set up, maintain, and inspect the
+tables of IPv6 packet
filter rules in the Linux kernel. Several different tables
may be defined. Each table contains a number of built-in
chains and may also contain user-defined chains.
-
+.PP
Each chain is a list of rules which can match a set of packets. Each
rule specifies what to do with a packet that matches. This is called
a `target', which may be a jump to a user-defined chain in the same
table.
-
.SH TARGETS
-A firewall rule specifies criteria for a packet, and a target. If the
+A firewall rule specifies criteria for a packet and a target. If the
packet does not match, the next rule in the chain is the examined; if
it does match, then the next rule is specified by the value of the
target, which can be the name of a user-defined chain or one of the
-special values
-.IR ACCEPT ,
-.IR DROP ,
-.IR QUEUE ,
-or
-.IR RETURN .
-.PP
-.I ACCEPT
-means to let the packet through.
-.I DROP
-means to drop the packet on the floor.
-.I QUEUE
-means to pass the packet to userspace (if supported by the kernel).
-.I RETURN
-means stop traversing this chain and resume at the next rule in the
+special values \fBACCEPT\fP, \fBDROP\fP, \fBQUEUE\fP or \fBRETURN\fP.
+.PP
+\fBACCEPT\fP means to let the packet through.
+\fBDROP\fP means to drop the packet on the floor.
+\fBQUEUE\fP means to pass the packet to userspace.
+(How the packet can be received
+by a userspace process differs by the particular queue handler. 2.4.x
+and 2.6.x kernels up to 2.6.13 include the \fBip_queue\fP
+queue handler. Kernels 2.6.14 and later additionally include the
+\fBnfnetlink_queue\fP queue handler. Packets with a target of QUEUE will be
+sent to queue number '0' in this case. Please also see the \fBNFQUEUE\fP
+target as described later in this man page.)
+\fBRETURN\fP means stop traversing this chain and resume at the next
+rule in the
previous (calling) chain. If the end of a built-in chain is reached
-or a rule in a built-in chain with target
-.I RETURN
+or a rule in a built-in chain with target \fBRETURN\fP
is matched, the target specified by the chain policy determines the
fate of the packet.
.SH TABLES
-There are currently two independent tables (which tables are present
+There are currently three independent tables (which tables are present
at any time depends on the kernel configuration options and which
-modules are present), as nat table has not been implemented yet.
+modules are present).
.TP
-.BI "-t, --table " "table"
+\fB\-t\fP, \fB\-\-table\fP \fItable\fP
This option specifies the packet matching table which the command
should operate on. If the kernel is configured with automatic module
loading, an attempt will be made to load the appropriate module for
The tables are as follows:
.RS
.TP .4i
-.BR "filter" :
-This is the default table (if no -t option is passed). It contains
-the built-in chains
-.B INPUT
-(for packets coming into the box itself),
-.B FORWARD
-(for packets being routed through the box), and
-.B OUTPUT
-(for locally-generated packets).
+\fBfilter\fP:
+This is the default table (if no \-t option is passed). It contains
+the built-in chains \fBINPUT\fP (for packets destined to local sockets),
+\fBFORWARD\fP (for packets being routed through the box), and
+\fBOUTPUT\fP (for locally-generated packets).
.TP
-.BR "mangle" :
+\fBmangle\fP:
This table is used for specialized packet alteration. Until kernel
-2.4.17 it had two built-in chains:
-.B PREROUTING
-(for altering incoming packets before routing) and
-.B OUTPUT
+2.4.17 it had two built-in chains: \fBPREROUTING\fP
+(for altering incoming packets before routing) and \fBOUTPUT\fP
(for altering locally-generated packets before routing).
Since kernel 2.4.18, three other built-in chains are also supported:
-.B INPUT
-(for packets coming into the box itself),
-.B FORWARD
-(for altering packets being routed through the box), and
-.B POSTROUTING
+\fBINPUT\fP (for packets coming into the box itself), \fBFORWARD\fP
+(for altering packets being routed through the box), and \fBPOSTROUTING\fP
(for altering packets as they are about to go out).
+.TP
+\fBraw\fP:
+This table is used mainly for configuring exemptions from connection
+tracking in combination with the NOTRACK target. It registers at the netfilter
+hooks with higher priority and is thus called before ip_conntrack, or any other
+IP tables. It provides the following built-in chains: \fBPREROUTING\fP
+(for packets arriving via any network interface) \fBOUTPUT\fP
+(for packets generated by local processes)
+.TP
+\fBsecurity\fP:
+This table is used for Mandatory Access Control (MAC) networking rules, such
+as those enabled by the \fBSECMARK\fP and \fBCONNSECMARK\fP targets.
+Mandatory Access Control is implemented by Linux Security Modules such as
+SELinux. The security table is called after the filter table, allowing any
+Discretionary Access Control (DAC) rules in the filter table to take effect
+before MAC rules. This table provides the following built-in chains:
+\fBINPUT\fP (for packets coming into the box itself),
+\fBOUTPUT\fP (for altering locally-generated packets before routing), and
+\fBFORWARD\fP (for altering packets being routed through the box).
.RE
.SH OPTIONS
The options that are recognized by
-.B ip6tables
-can be divided into several different groups.
+\fBip6tables\fP can be divided into several different groups.
.SS COMMANDS
These options specify the specific action to perform. Only one of them
can be specified on the command line unless otherwise specified
below. For all the long versions of the command and option names, you
need to use only enough letters to ensure that
-.B ip6tables
-can differentiate it from all other options.
+\fBip6tables\fP can differentiate it from all other options.
.TP
-.BI "-A, --append " "chain rule-specification"
+\fB\-A\fP, \fB\-\-append\fP \fIchain rule-specification\fP
Append one or more rules to the end of the selected chain.
When the source and/or destination names resolve to more than one
address, a rule will be added for each possible address combination.
.TP
-.BI "-D, --delete " "chain rule-specification"
+\fB\-C\fP, \fB\-\-check\fP \fIchain rule-specification\fP
+Check whether a rule matching the specification does exist in the
+selected chain. This command uses the same logic as \fB\-D\fP to
+find a matching entry, but does not alter the existing iptables
+configuration and uses its exit code to indicate success or failure.
+.TP
+\fB\-D\fP, \fB\-\-delete\fP \fIchain rule-specification\fP
.ns
.TP
-.BI "-D, --delete " "chain rulenum"
+\fB\-D\fP, \fB\-\-delete\fP \fIchain rulenum\fP
Delete one or more rules from the selected chain. There are two
versions of this command: the rule can be specified as a number in the
chain (starting at 1 for the first rule) or a rule to match.
.TP
-.B "-I, --insert"
+\fB\-I\fP, \fB\-\-insert\fP \fIchain\fP [\fIrulenum\fP] \fIrule-specification\fP
Insert one or more rules in the selected chain as the given rule
number. So, if the rule number is 1, the rule or rules are inserted
at the head of the chain. This is also the default if no rule number
is specified.
.TP
-.BI "-R, --replace " "chain rulenum rule-specification"
+\fB\-R\fP, \fB\-\-replace\fP \fIchain rulenum rule-specification\fP
Replace a rule in the selected chain. If the source and/or
destination names resolve to multiple addresses, the command will
fail. Rules are numbered starting at 1.
.TP
-.BR "-L, --list " "[\fIchain\fP]"
+\fB\-L\fP, \fB\-\-list\fP [\fIchain\fP]
List all rules in the selected chain. If no chain is selected, all
-chains are listed. As every other iptables command, it applies to the
-specified table (filter is the default), so mangle rules get listed by
-.nf
- ip6tables -t mangle -n -L
-.fi
-Please note that it is often used with the
-.B -n
+chains are listed. Like every other ip6tables command, it applies to the
+specified table (filter is the default).
+.IP ""
+Please note that it is often used with the \fB\-n\fP
option, in order to avoid long reverse DNS lookups.
-It is legal to specify the
-.B -Z
+It is legal to specify the \fB\-Z\fP
(zero) option as well, in which case the chain(s) will be atomically
listed and zeroed. The exact output is affected by the other
arguments given. The exact rules are suppressed until you use
.nf
- ip6tables -L -v
+ ip6tables \-L \-v
.fi
.TP
-.BR "-F, --flush " "[\fIchain\fP]"
+\fB\-S\fP, \fB\-\-list\-rules\fP [\fIchain\fP]
+Print all rules in the selected chain. If no chain is selected, all
+chains are printed like ip6tables-save. Like every other ip6tables command,
+it applies to the specified table (filter is the default).
+.TP
+\fB\-F\fP, \fB\-\-flush\fP [\fIchain\fP]
Flush the selected chain (all the chains in the table if none is given).
This is equivalent to deleting all the rules one by one.
.TP
-.BR "-Z, --zero " "[\fIchain\fP]"
-Zero the packet and byte counters in all chains. It is legal to
+\fB\-Z\fP, \fB\-\-zero\fP [\fIchain\fP [\fIrulenum\fP]]
+Zero the packet and byte counters in all chains, or only the given chain,
+or only the given rule in a chain. It is legal to
specify the
-.B "-L, --list"
+\fB\-L\fP, \fB\-\-list\fP
(list) option as well, to see the counters immediately before they are
cleared. (See above.)
.TP
-.BI "-N, --new-chain " "chain"
+\fB\-N\fP, \fB\-\-new\-chain\fP \fIchain\fP
Create a new user-defined chain by the given name. There must be no
target of that name already.
.TP
-.BR "-X, --delete-chain " "[\fIchain\fP]"
+\fB\-X\fP, \fB\-\-delete\-chain\fP [\fIchain\fP]
Delete the optional user-defined chain specified. There must be no references
-to the chain. If there are, you must delete or replace the referring
-rules before the chain can be deleted. If no argument is given, it
-will attempt to delete every non-builtin chain in the table.
+to the chain. If there are, you must delete or replace the referring rules
+before the chain can be deleted. The chain must be empty, i.e. not contain
+any rules. If no argument is given, it will attempt to delete every
+non-builtin chain in the table.
.TP
-.BI "-P, --policy " "chain target"
-Set the policy for the chain to the given target. See the section
-.B TARGETS
+\fB\-P\fP, \fB\-\-policy\fP \fIchain target\fP
+Set the policy for the chain to the given target. See the section \fBTARGETS\fP
for the legal targets. Only built-in (non-user-defined) chains can have
policies, and neither built-in nor user-defined chains can be policy
targets.
.TP
-.BI "-E, --rename-chain " "old-chain new-chain"
+\fB\-E\fP, \fB\-\-rename\-chain\fP \fIold\-chain new\-chain\fP
Rename the user specified chain to the user supplied name. This is
cosmetic, and has no effect on the structure of the table.
.TP
-.B -h
+\fB\-A\fP, \fB\-\-append\fP \fIchain rule-specification\fP
+Append one or more rules to the end of the selected chain.
+When the source and/or destination names resolve to more than one
+address, a rule will be added for each possible address combination.
+.TP
+\fB\-h\fP
Help.
Give a (currently very brief) description of the command syntax.
.SS PARAMETERS
The following parameters make up a rule specification (as used in the
add, delete, insert, replace and append commands).
.TP
-.BR "-p, --protocol " "[!] \fIprotocol\fP"
+[\fB!\fP] \fB\-p\fP, \fB\-\-protocol\fP \fIprotocol\fP
The protocol of the rule or of the packet to check.
-The specified protocol can be one of
-.IR tcp ,
-.IR udp ,
-.IR ipv6-icmp|icmpv6 ,
-or
-.IR all ,
+The specified protocol can be one of \fBtcp\fP, \fBudp\fP, \fBudplite\fP,
+\fBicmpv6\fP, \fBesp\fP, \fBmh\fP or the special keyword "\fBall\fP",
or it can be a numeric value, representing one of these protocols or a
-different one. A protocol name from /etc/protocols is also allowed.
+different one. A protocol name from /etc/protocols is also allowed.
+But IPv6 extension headers except \fBesp\fP are not allowed.
+\fBesp\fP and \fBipv6\-nonext\fP
+can be used with Kernel version 2.6.11 or later.
A "!" argument before the protocol inverts the
-test. The number zero is equivalent to
-.IR all .
-Protocol
-.I all
+test. The number zero is equivalent to \fBall\fP, which means that you cannot
+test the protocol field for the value 0 directly. To match on a HBH header,
+even if it were the last, you cannot use \fB\-p 0\fP, but always need
+\fB\-m hbh\fP.
+"\fBall\fP"
will match with all protocols and is taken as default when this
option is omitted.
.TP
-.BR "-s, --source " "[!] \fIaddress\fP[/\fImask\fP]"
+[\fB!\fP] \fB\-s\fP, \fB\-\-source\fP \fIaddress\fP[\fB/\fP\fImask\fP]
Source specification.
-.I Address
-can be either a hostname (please note that specifying
-any name to be resolved with a remote query such as DNS is a really bad idea),
-a network IPv6 address (with /mask), or a plain IPv6 address.
-(the network name isn't supported now).
-The
-.I mask
-can be either a network mask or a plain number,
+\fIAddress\fP can be either be a hostname,
+a network IP address (with \fB/\fP\fImask\fP), or a plain IP address.
+Names will be resolved once only, before the rule is submitted to the kernel.
+Please note that specifying any name to be resolved with a remote query such as
+DNS is a really bad idea.
+(Resolving network names is not supported at this time.)
+The \fImask\fP is a plain number,
specifying the number of 1's at the left side of the network mask.
-Thus, a mask of
-.I 64
-is equivalent to
-.IR ffff:ffff:ffff:ffff:0000:0000:0000:0000 .
A "!" argument before the address specification inverts the sense of
-the address. The flag
-.B --src
+the address. The flag \fB\-\-src\fP
is an alias for this option.
+Multiple addresses can be specified, but this will \fBexpand to multiple
+rules\fP (when adding with \-A), or will cause multiple rules to be
+deleted (with \-D).
.TP
-.BR "-d, --destination " "[!] \fIaddress\fP[/\fImask\fP]"
+[\fB!\fP] \fB\-d\fP, \fB\-\-destination\fP \fIaddress\fP[\fB/\fP\fImask\fP]
Destination specification.
-See the description of the
-.B -s
+See the description of the \fB\-s\fP
(source) flag for a detailed description of the syntax. The flag
-.B --dst
-is an alias for this option.
+\fB\-\-dst\fP is an alias for this option.
.TP
-.BI "-j, --jump " "target"
+\fB\-j\fP, \fB\-\-jump\fP \fItarget\fP
This specifies the target of the rule; i.e., what to do if the packet
matches it. The target can be a user-defined chain (other than the
one this rule is in), one of the special builtin targets which decide
-the fate of the packet immediately, or an extension (see
-.B EXTENSIONS
+the fate of the packet immediately, or an extension (see \fBEXTENSIONS\fP
below). If this
-option is omitted in a rule, then matching the rule will have no
+option is omitted in a rule (and \fB\-g\fP
+is not used), then matching the rule will have no
effect on the packet's fate, but the counters on the rule will be
incremented.
.TP
-.BR "-i, --in-interface " "[!] \fIname\fP"
-Name of an interface via which a packet is going to be received (only for
-packets entering the
-.BR INPUT ,
-.B FORWARD
-and
-.B PREROUTING
+\fB\-g\fP, \fB\-\-goto\fP \fIchain\fP
+This specifies that the processing should continue in a user
+specified chain. Unlike the \-\-jump option return will not continue
+processing in this chain but instead in the chain that called us via
+\-\-jump.
+.TP
+[\fB!\fP] \fB\-i\fP, \fB\-\-in\-interface\fP \fIname\fP
+Name of an interface via which a packet was received (only for
+packets entering the \fBINPUT\fP, \fBFORWARD\fP and \fBPREROUTING\fP
chains). When the "!" argument is used before the interface name, the
sense is inverted. If the interface name ends in a "+", then any
interface which begins with this name will match. If this option is
omitted, any interface name will match.
.TP
-.BR "-o, --out-interface " "[!] \fIname\fP"
+[\fB!\fP] \fB\-o\fP, \fB\-\-out\-interface\fP \fIname\fP
Name of an interface via which a packet is going to be sent (for packets
-entering the
-.BR FORWARD
-and
-.B OUTPUT
+entering the \fBFORWARD\fP, \fBOUTPUT\fP and \fBPOSTROUTING\fP
chains). When the "!" argument is used before the interface name, the
sense is inverted. If the interface name ends in a "+", then any
interface which begins with this name will match. If this option is
omitted, any interface name will match.
-.TP
.\" Currently not supported (header-based)
-.\"
-.\" .B "[!] " "-f, --fragment"
+.\" .TP
+.\" [\fB!\fP] \fB\-f\fP, \fB\-\-fragment\fP
.\" This means that the rule only refers to second and further fragments
.\" of fragmented packets. Since there is no way to tell the source or
.\" destination ports of such a packet (or ICMP type), such a packet will
.\" not match any rules which specify them. When the "!" argument
-.\" precedes the "-f" flag, the rule will only match head fragments, or
+.\" precedes the "\-f" flag, the rule will only match head fragments, or
.\" unfragmented packets.
-.\" .TP
-.B "-c, --set-counters " "PKTS BYTES"
+.TP
+\fB\-c\fP, \fB\-\-set\-counters\fP \fIpackets bytes\fP
This enables the administrator to initialize the packet and byte
-counters of a rule (during
-.B INSERT,
-.B APPEND,
-.B REPLACE
+counters of a rule (during \fBINSERT\fP, \fBAPPEND\fP, \fBREPLACE\fP
operations).
.SS "OTHER OPTIONS"
The following additional options can be specified:
.TP
-.B "-v, --verbose"
+\fB\-v\fP, \fB\-\-verbose\fP
Verbose output. This option makes the list command show the interface
name, the rule options (if any), and the TOS masks. The packet and
byte counters are also listed, with the suffix 'K', 'M' or 'G' for
1000, 1,000,000 and 1,000,000,000 multipliers respectively (but see
-the
-.B -x
-flag to change this).
+the \fB\-x\fP flag to change this).
For appending, insertion, deletion and replacement, this causes
-detailed information on the rule or rules to be printed.
+detailed information on the rule or rules to be printed. \fB\-v\fP may be
+specified multiple times to possibly emit more detailed debug statements.
.TP
-.B "-n, --numeric"
+\fB\-n\fP, \fB\-\-numeric\fP
Numeric output.
IP addresses and port numbers will be printed in numeric format.
By default, the program will try to display them as host names,
network names, or services (whenever applicable).
.TP
-.B "-x, --exact"
+\fB\-x\fP, \fB\-\-exact\fP
Expand numbers.
Display the exact value of the packet and byte counters,
instead of only the rounded number in K's (multiples of 1000)
M's (multiples of 1000K) or G's (multiples of 1000M). This option is
-only relevant for the
-.B -L
-command.
+only relevant for the \fB\-L\fP command.
.TP
-.B "--line-numbers"
+\fB\-\-line\-numbers\fP
When listing rules, add line numbers to the beginning of each rule,
corresponding to that rule's position in the chain.
.TP
-.B "--modprobe=command"
-When adding or inserting rules into a chain, use
-.B command
+\fB\-\-modprobe=\fP\fIcommand\fP
+When adding or inserting rules into a chain, use \fIcommand\fP
to load any necessary modules (targets, match extensions, etc).
.SH MATCH EXTENSIONS
-ip6tables can use extended packet matching modules. These are loaded
-in two ways: implicitly, when
-.B -p
-or
-.B --protocol
-is specified, or with the
-.B -m
-or
-.B --match
+.PP
+ip6tables can use extended packet matching modules
+with the \fB\-m\fP or \fB\-\-match\fP
options, followed by the matching module name; after these, various
extra command line options become available, depending on the specific
module. You can specify multiple extended match modules in one line,
-and you can use the
-.B -h
-or
-.B --help
+and you can use the \fB\-h\fP or \fB\-\-help\fP
options after the module has been specified to receive help specific
to that module.
-
-The following are included in the base package, and most of these can
-be preceded by a
-.B !
-to invert the sense of the match.
-.SS tcp
-These extensions are loaded if `--protocol tcp' is specified. It
-provides the following options:
+.PP
+If the \fB\-p\fP or \fB\-\-protocol\fP was specified and if and only if an
+unknown option is encountered, ip6tables will try load a match module of the
+same name as the protocol, to try making the option available.
+.\" @MATCH@
+.SS addrtype
+This module matches packets based on their
+.B address type.
+Address types are used within the kernel networking stack and categorize
+addresses into various groups. The exact definition of that group depends on the specific layer three protocol.
+.PP
+The following address types are possible:
.TP
-.BR "--source-port " "[!] \fIport\fP[:\fIport\fP]"
-Source port or port range specification. This can either be a service
-name or a port number. An inclusive range can also be specified,
-using the format
-.IR port : port .
-If the first port is omitted, "0" is assumed; if the last is omitted,
-"65535" is assumed.
-If the second port greater then the first they will be swapped.
-The flag
-.B --sport
-is a convenient alias for this option.
+.BI "UNSPEC"
+an unspecified address (i.e. 0.0.0.0)
.TP
-.BR "--destination-port " "[!] \fIport\fP[:\fIport\fP]"
-Destination port or port range specification. The flag
-.B --dport
-is a convenient alias for this option.
+.BI "UNICAST"
+an unicast address
.TP
-.BR "--tcp-flags " "[!] \fImask\fP \fIcomp\fP"
-Match when the TCP flags are as specified. The first argument is the
-flags which we should examine, written as a comma-separated list, and
-the second argument is a comma-separated list of flags which must be
-set. Flags are:
-.BR "SYN ACK FIN RST URG PSH ALL NONE" .
-Hence the command
-.nf
- ip6tables -A FORWARD -p tcp --tcp-flags SYN,ACK,FIN,RST SYN
-.fi
-will only match packets with the SYN flag set, and the ACK, FIN and
-RST flags unset.
+.BI "LOCAL"
+a local address
.TP
-.B "[!] --syn"
-Only match TCP packets with the SYN bit set and the ACK and RST bits
-cleared. Such packets are used to request TCP connection initiation;
-for example, blocking such packets coming in an interface will prevent
-incoming TCP connections, but outgoing TCP connections will be
-unaffected.
-It is equivalent to \fB--tcp-flags SYN,RST,ACK SYN\fP.
-If the "!" flag precedes the "--syn", the sense of the
-option is inverted.
+.BI "BROADCAST"
+a broadcast address
.TP
-.BR "--tcp-option " "[!] \fInumber\fP"
-Match if TCP option set.
-.SS udp
-These extensions are loaded if `--protocol udp' is specified. It
-provides the following options:
+.BI "ANYCAST"
+an anycast packet
.TP
-.BR "--source-port " "[!] \fIport\fP[:\fIport\fP]"
-Source port or port range specification.
-See the description of the
-.B --source-port
-option of the TCP extension for details.
+.BI "MULTICAST"
+a multicast address
.TP
-.BR "--destination-port " "[!] \fIport\fP[:\fIport\fP]"
-Destination port or port range specification.
-See the description of the
-.B --destination-port
-option of the TCP extension for details.
-.SS ipv6-icmp
-This extension is loaded if `--protocol ipv6-icmp' or `--protocol icmpv6' is
-specified. It provides the following option:
+.BI "BLACKHOLE"
+a blackhole address
.TP
-.BR "--icmpv6-type " "[!] \fItypename\fP"
-This allows specification of the ICMP type, which can be a numeric
-IPv6-ICMP type, or one of the IPv6-ICMP type names shown by the command
-.nf
- ip6tables -p ipv6-icmp -h
-.fi
-.SS mac
+.BI "UNREACHABLE"
+an unreachable address
.TP
-.BR "--mac-source " "[!] \fIaddress\fP"
-Match source MAC address. It must be of the form XX:XX:XX:XX:XX:XX.
-Note that this only makes sense for packets coming from an Ethernet device
-and entering the
-.BR PREROUTING ,
-.B FORWARD
-or
-.B INPUT
-chains.
-.SS limit
-This module matches at a limited rate using a token bucket filter.
-A rule using this extension will match until this limit is reached
-(unless the `!' flag is used). It can be used in combination with the
-.B LOG
-target to give limited logging, for example.
+.BI "PROHIBIT"
+a prohibited address
.TP
-.BI "--limit " "rate"
-Maximum average matching rate: specified as a number, with an optional
-`/second', `/minute', `/hour', or `/day' suffix; the default is
-3/hour.
+.BI "THROW"
+FIXME
.TP
-.BI "--limit-burst " "number"
-Maximum initial number of packets to match: this number gets
-recharged by one every time the limit specified above is not reached,
-up to this number; the default is 5.
-.SS multiport
-This module matches a set of source or destination ports. Up to 15
-ports can be specified. It can only be used in conjunction with
-.B "-p tcp"
-or
-.BR "-p udp" .
+.BI "NAT"
+FIXME
.TP
-.BR "--source-ports " "\fIport\fP[,\fIport\fP[,\fIport\fP...]]"
-Match if the source port is one of the given ports. The flag
-.B --sports
-is a convenient alias for this option.
+.BI "XRESOLVE"
.TP
-.BR "--destination-ports " "\fIport\fP[,\fIport\fP[,\fIport\fP...]]"
-Match if the destination port is one of the given ports. The flag
-.B --dports
-is a convenient alias for this option.
+[\fB!\fP] \fB\-\-src\-type\fP \fItype\fP
+Matches if the source address is of given type
.TP
-.BR "--ports " "\fIport\fP[,\fIport\fP[,\fIport\fP...]]"
-Match if the both the source and destination ports are equal to each
-other and to one of the given ports.
-.SS mark
-This module matches the netfilter mark field associated with a packet
-(which can be set using the
-.B MARK
-target below).
+[\fB!\fP] \fB\-\-dst\-type\fP \fItype\fP
+Matches if the destination address is of given type
.TP
-.BR "--mark " "\fIvalue\fP[/\fImask\fP]"
-Matches packets with the given unsigned mark value (if a mask is
-specified, this is logically ANDed with the mask before the
-comparison).
-.SS owner
-This module attempts to match various characteristics of the packet
-creator, for locally-generated packets. It is only valid in the
+.BI "\-\-limit\-iface\-in"
+The address type checking can be limited to the interface the packet is coming
+in. This option is only valid in the
+.BR PREROUTING ,
+.B INPUT
+and
+.B FORWARD
+chains. It cannot be specified with the
+\fB\-\-limit\-iface\-out\fP
+option.
+.TP
+\fB\-\-limit\-iface\-out\fP
+The address type checking can be limited to the interface the packet is going
+out. This option is only valid in the
+.BR POSTROUTING ,
.B OUTPUT
-chain, and even this some packets (such as ICMP ping responses) may
-have no owner, and hence never match. This is regarded as experimental.
-.TP
-.BI "--uid-owner " "userid"
-Matches if the packet was created by a process with the given
-effective user id.
-.TP
-.BI "--gid-owner " "groupid"
-Matches if the packet was created by a process with the given
-effective group id.
-.TP
-.BI "--pid-owner " "processid"
-Matches if the packet was created by a process with the given
-process id.
-.TP
-.BI "--sid-owner " "sessionid"
-Matches if the packet was created by a process in the given session
-group.
-.\" .SS state
-.\" This module, when combined with connection tracking, allows access to
-.\" the connection tracking state for this packet.
-.\" .TP
-.\" .BI "--state " "state"
-.\" Where state is a comma separated list of the connection states to
-.\" match. Possible states are
-.\" .B INVALID
-.\" meaning that the packet is associated with no known connection,
-.\" .B ESTABLISHED
-.\" meaning that the packet is associated with a connection which has seen
-.\" packets in both directions,
-.\" .B NEW
-.\" meaning that the packet has started a new connection, or otherwise
-.\" associated with a connection which has not seen packets in both
-.\" directions, and
-.\" .B RELATED
-.\" meaning that the packet is starting a new connection, but is
-.\" associated with an existing connection, such as an FTP data transfer,
-.\" or an ICMP error.
-.\" .SS unclean
-.\" This module takes no options, but attempts to match packets which seem
-.\" malformed or unusual. This is regarded as experimental.
-.\" .SS tos
-.\" This module matches the 8 bits of Type of Service field in the IP
-.\" header (ie. including the precedence bits).
-.\" .TP
-.\" .BI "--tos " "tos"
-.\" The argument is either a standard name, (use
-.\" .br
-.\" iptables -m tos -h
-.\" .br
-.\" to see the list), or a numeric value to match.
-.SH TARGET EXTENSIONS
-ip6tables can use extended target modules: the following are included
-in the standard distribution.
-.SS LOG
-Turn on kernel logging of matching packets. When this option is set
-for a rule, the Linux kernel will print some information on all
-matching packets (like most IPv6 IPv6-header fields) via the kernel log
-(where it can be read with
-.I dmesg
-or
-.IR syslogd (8)).
-This is a "non-terminating target", i.e. rule traversal continues at
-the next rule. So if you want to LOG the packets you refuse, use two
-separate rules with the same matching criteria, first using target LOG
-then DROP (or REJECT).
+and
+.B FORWARD
+chains. It cannot be specified with the
+\fB\-\-limit\-iface\-in\fP
+option.
+.SS ah
+This module matches the parameters in Authentication header of IPsec packets.
.TP
-.BI "--log-level " "level"
-Level of logging (numeric or see \fIsyslog.conf\fP(5)).
+[\fB!\fP] \fB\-\-ahspi\fP \fIspi\fP[\fB:\fP\fIspi\fP]
+Matches SPI.
.TP
-.BI "--log-prefix " "prefix"
-Prefix log messages with the specified prefix; up to 29 letters long,
-and useful for distinguishing messages in the logs.
+[\fB!\fP] \fB\-\-ahlen\fP \fIlength\fP
+Total length of this header in octets.
.TP
-.B --log-tcp-sequence
-Log TCP sequence numbers. This is a security risk if the log is
-readable by users.
+\fB\-\-ahres\fP
+Matches if the reserved field is filled with zero.
+.SS cluster
+Allows you to deploy gateway and back-end load-sharing clusters without the
+need of load-balancers.
+.PP
+This match requires that all the nodes see the same packets. Thus, the cluster
+match decides if this node has to handle a packet given the following options:
.TP
-.B --log-tcp-options
-Log options from the TCP packet header.
+\fB\-\-cluster\-total\-nodes\fP \fInum\fP
+Set number of total nodes in cluster.
.TP
-.B --log-ip-options
-Log options from the IPv6 packet header.
-.SS MARK
-This is used to set the netfilter mark value associated with the
-packet. It is only valid in the
-.B mangle
-table.
+[\fB!\fP] \fB\-\-cluster\-local\-node\fP \fInum\fP
+Set the local node number ID.
.TP
-.BI "--set-mark " "mark"
-.SS REJECT
-This is used to send back an error packet in response to the matched
-packet: otherwise it is equivalent to
-.B DROP
-so it is a terminating TARGET, ending rule traversal.
-This target is only valid in the
-.BR INPUT ,
-.B FORWARD
-and
-.B OUTPUT
-chains, and user-defined chains which are only called from those
-chains. The following option controls the nature of the error packet
-returned:
+[\fB!\fP] \fB\-\-cluster\-local\-nodemask\fP \fImask\fP
+Set the local node number ID mask. You can use this option instead
+of \fB\-\-cluster\-local\-node\fP.
.TP
-.BI "--reject-with " "type"
-The type given can be
-.nf
-.B " icmp6-no-route"
-.B " no-route"
-.B " icmp6-adm-prohibited"
-.B " adm-prohibited"
-.B " icmp6-addr-unreachable"
-.B " addr-unreach"
-.B " icmp6-port-unreachable"
-.B " port-unreach"
-.fi
-which return the appropriate IPv6-ICMP error message (\fBport-unreach\fP is
-the default). Finally, the option
-.B tcp-reset
-can be used on rules which only match the TCP protocol: this causes a
-TCP RST packet to be sent back. This is mainly useful for blocking
-.I ident
-(113/tcp) probes which frequently occur when sending mail to broken mail
-hosts (which won't accept your mail otherwise).
-.\" .SS TOS
-.\" This is used to set the 8-bit Type of Service field in the IP header.
-.\" It is only valid in the
-.\" .B mangle
-.\" table.
-.\" .TP
-.\" .BI "--set-tos " "tos"
-.\" You can use a numeric TOS values, or use
-.\" .br
-.\" iptables -j TOS -h
-.\" .br
-.\" to see the list of valid TOS names.
-.\" .SS MIRROR
-.\" This is an experimental demonstration target which inverts the source
-.\" and destination fields in the IP header and retransmits the packet.
-.\" It is only valid in the
-.\" .BR INPUT ,
-.\" .B FORWARD
-.\" and
-.\" .B PREROUTING
-.\" chains, and user-defined chains which are only called from those
-.\" chains. Note that the outgoing packets are
-.\" .B NOT
-.\" seen by any packet filtering chains, connection tracking or NAT, to
-.\" avoid loops and other problems.
-.\" .SS SNAT
-.\" This target is only valid in the
-.\" .B nat
-.\" table, in the
-.\" .B POSTROUTING
-.\" chain. It specifies that the source address of the packet should be
-.\" modified (and all future packets in this connection will also be
-.\" mangled), and rules should cease being examined. It takes one option:
-.\" .TP
-.\" .BR "--to-source " "\fIipaddr\fP[-\fIipaddr\fP][:\fIport\fP-\fIport\fP]"
-.\" which can specify a single new source IP address, an inclusive range
-.\" of IP addresses, and optionally, a port range (which is only valid if
-.\" the rule also specifies
-.\" .B "-p tcp"
-.\" or
-.\" .BR "-p udp" ).
-.\" If no port range is specified, then source ports below 512 will be
-.\" mapped to other ports below 512: those between 512 and 1023 inclusive
-.\" will be mapped to ports below 1024, and other ports will be mapped to
-.\" 1024 or above. Where possible, no port alteration will occur.
-.\" .SS DNAT
-.\" This target is only valid in the
-.\" .B nat
-.\" table, in the
-.\" .B PREROUTING
-.\" and
-.\" .B OUTPUT
-.\" chains, and user-defined chains which are only called from those
-.\" chains. It specifies that the destination address of the packet
-.\" should be modified (and all future packets in this connection will
-.\" also be mangled), and rules should cease being examined. It takes one
-.\" option:
-.\" .TP
-.\" .BR "--to-destination " "\fIipaddr\fP[-\fIipaddr\fP][:\fIport\fP-\fIport\fP]"
-.\" which can specify a single new destination IP address, an inclusive
-.\" range of IP addresses, and optionally, a port range (which is only
-.\" valid if the rule also specifies
-.\" .B "-p tcp"
-.\" or
-.\" .BR "-p udp" ).
-.\" If no port range is specified, then the destination port will never be
-.\" modified.
-.\" .SS MASQUERADE
-.\" This target is only valid in the
-.\" .B nat
-.\" table, in the
-.\" .B POSTROUTING
-.\" chain. It should only be used with dynamically assigned IP (dialup)
-.\" connections: if you have a static IP address, you should use the SNAT
-.\" target. Masquerading is equivalent to specifying a mapping to the IP
-.\" address of the interface the packet is going out, but also has the
-.\" effect that connections are
-.\" .I forgotten
-.\" when the interface goes down. This is the correct behavior when the
-.\" next dialup is unlikely to have the same interface address (and hence
-.\" any established connections are lost anyway). It takes one option:
-.\" .TP
-.\" .BR "--to-ports " "\fIport\fP[-\fIport\fP]"
-.\" This specifies a range of source ports to use, overriding the default
-.\" .B SNAT
-.\" source port-selection heuristics (see above). This is only valid
-.\" if the rule also specifies
-.\" .B "-p tcp"
-.\" or
-.\" .BR "-p udp" .
-.\" .SS REDIRECT
-.\" This target is only valid in the
-.\" .B nat
-.\" table, in the
-.\" .B PREROUTING
-.\" and
-.\" .B OUTPUT
-.\" chains, and user-defined chains which are only called from those
-.\" chains. It alters the destination IP address to send the packet to
-.\" the machine itself (locally-generated packets are mapped to the
-.\" 127.0.0.1 address). It takes one option:
-.\" .TP
-.\" .BR "--to-ports " "\fIport\fP[-\fIport\fP]"
-.\" This specifies a destination port or range of ports to use: without
-.\" this, the destination port is never altered. This is only valid
-.\" if the rule also specifies
-.\" .B "-p tcp"
-.\" or
-.\" .BR "-p udp" .
-.SH DIAGNOSTICS
-Various error messages are printed to standard error. The exit code
-is 0 for correct functioning. Errors which appear to be caused by
-invalid or abused command line parameters cause an exit code of 2, and
-other errors cause an exit code of 1.
-.SH BUGS
-Bugs? What's this? ;-)
-Well... the counters are not reliable on sparc64.
-.SH COMPATIBILITY WITH IPCHAINS
-This
-.B ip6tables
-is very similar to ipchains by Rusty Russell. The main difference is
-that the chains
-.B INPUT
-and
-.B OUTPUT
-are only traversed for packets coming into the local host and
-originating from the local host respectively. Hence every packet only
-passes through one of the three chains (except loopback traffic, which
-involves both INPUT and OUTPUT chains); previously a forwarded packet
-would pass through all three.
+\fB\-\-cluster\-hash\-seed\fP \fIvalue\fP
+Set seed value of the Jenkins hash.
.PP
-The other main difference is that
-.B -i
-refers to the input interface;
-.B -o
-refers to the output interface, and both are available for packets
-entering the
-.B FORWARD
-chain.
-.\" .PP The various forms of NAT have been separated out;
-.\" .B iptables
-.\" is a pure packet filter when using the default `filter' table, with
-.\" optional extension modules. This should simplify much of the previous
-.\" confusion over the combination of IP masquerading and packet filtering
-.\" seen previously. So the following options are handled differently:
-.\" .br
-.\" -j MASQ
-.\" .br
-.\" -M -S
-.\" .br
-.\" -M -L
-.\" .br
-There are several other changes in ip6tables.
-.SH SEE ALSO
-.BR ip6tables-save (8),
-.BR ip6tables-restore(8),
-.BR iptables (8),
-.BR iptables-save (8),
-.BR iptables-restore (8).
-.P
-The packet-filtering-HOWTO details iptables usage for
-packet filtering, the NAT-HOWTO details NAT,
-the netfilter-extensions-HOWTO details the extensions that are
-not in the standard distribution,
-and the netfilter-hacking-HOWTO details the netfilter internals.
-.br
-See
-.BR "http://www.netfilter.org/" .
-.SH AUTHORS
-Rusty Russell wrote iptables, in early consultation with Michael
-Neuling.
+Example:
+.IP
+iptables \-A PREROUTING \-t mangle \-i eth1 \-m cluster
+\-\-cluster\-total\-nodes 2 \-\-cluster\-local\-node 1
+\-\-cluster\-hash\-seed 0xdeadbeef
+\-j MARK \-\-set-mark 0xffff
+.IP
+iptables \-A PREROUTING \-t mangle \-i eth2 \-m cluster
+\-\-cluster\-total\-nodes 2 \-\-cluster\-local\-node 1
+\-\-cluster\-hash\-seed 0xdeadbeef
+\-j MARK -\-set\-mark 0xffff
+.IP
+iptables \-A PREROUTING \-t mangle \-i eth1
+\-m mark ! \-\-mark 0xffff \-j DROP
+.IP
+iptables \-A PREROUTING \-t mangle \-i eth2
+\-m mark ! \-\-mark 0xffff \-j DROP
.PP
-Marc Boucher made Rusty abandon ipnatctl by lobbying for a generic packet
-selection framework in iptables, then wrote the mangle table, the owner match,
-the mark stuff, and ran around doing cool stuff everywhere.
+And the following commands to make all nodes see the same packets:
+.IP
+ip maddr add 01:00:5e:00:01:01 dev eth1
+.IP
+ip maddr add 01:00:5e:00:01:02 dev eth2
+.IP
+arptables \-A OUTPUT \-o eth1 \-\-h\-length 6
+\-j mangle \-\-mangle-mac-s 01:00:5e:00:01:01
+.IP
+arptables \-A INPUT \-i eth1 \-\-h-length 6
+\-\-destination-mac 01:00:5e:00:01:01
+\-j mangle \-\-mangle\-mac\-d 00:zz:yy:xx:5a:27
+.IP
+arptables \-A OUTPUT \-o eth2 \-\-h\-length 6
+\-j mangle \-\-mangle\-mac\-s 01:00:5e:00:01:02
+.IP
+arptables \-A INPUT \-i eth2 \-\-h\-length 6
+\-\-destination\-mac 01:00:5e:00:01:02
+\-j mangle \-\-mangle\-mac\-d 00:zz:yy:xx:5a:27
.PP
-James Morris wrote the TOS target, and tos match.
+In the case of TCP connections, pickup facility has to be disabled
+to avoid marking TCP ACK packets coming in the reply direction as
+valid.
+.IP
+echo 0 > /proc/sys/net/netfilter/nf_conntrack_tcp_loose
+.SS comment
+Allows you to add comments (up to 256 characters) to any rule.
+.TP
+\fB\-\-comment\fP \fIcomment\fP
+.TP
+Example:
+iptables \-A INPUT \-i eth1 \-m comment \-\-comment "my local LAN"
+.SS connbytes
+Match by how many bytes or packets a connection (or one of the two
+flows constituting the connection) has transferred so far, or by
+average bytes per packet.
.PP
-Jozsef Kadlecsik wrote the REJECT target.
+The counters are 64-bit and are thus not expected to overflow ;)
.PP
-Harald Welte wrote the ULOG target, TTL match+target and libipulog.
+The primary use is to detect long-lived downloads and mark them to be
+scheduled using a lower priority band in traffic control.
.PP
-The Netfilter Core Team is: Marc Boucher, Martin Josefsson, Jozsef Kadlecsik,
-James Morris, Harald Welte and Rusty Russell.
+The transferred bytes per connection can also be viewed through
+`conntrack \-L` and accessed via ctnetlink.
.PP
-ip6tables man page created by Andras Kis-Szabo, based on
-iptables man page written by Herve Eychenne <rv@wallfire.org>.
-.\" .. and did I mention that we are incredibly cool people?
-.\" .. sexy, too ..
-.\" .. witty, charming, powerful ..
-.\" .. and most of all, modest ..
+NOTE that for connections which have no accounting information, the match will
+always return false. The "net.netfilter.nf_conntrack_acct" sysctl flag controls
+whether \fBnew\fP connections will be byte/packet counted. Existing connection
+flows will not be gaining/losing a/the accounting structure when be sysctl flag
+is flipped.
+.TP
+[\fB!\fP] \fB\-\-connbytes\fP \fIfrom\fP[\fB:\fP\fIto\fP]
+match packets from a connection whose packets/bytes/average packet
+size is more than FROM and less than TO bytes/packets. if TO is
+omitted only FROM check is done. "!" is used to match packets not
+falling in the range.
+.TP
+\fB\-\-connbytes\-dir\fP {\fBoriginal\fP|\fBreply\fP|\fBboth\fP}
+which packets to consider
+.TP
+\fB\-\-connbytes\-mode\fP {\fBpackets\fP|\fBbytes\fP|\fBavgpkt\fP}
+whether to check the amount of packets, number of bytes transferred or
+the average size (in bytes) of all packets received so far. Note that
+when "both" is used together with "avgpkt", and data is going (mainly)
+only in one direction (for example HTTP), the average packet size will
+be about half of the actual data packets.
+.TP
+Example:
+iptables .. \-m connbytes \-\-connbytes 10000:100000 \-\-connbytes\-dir both \-\-connbytes\-mode bytes ...
+.SS connlimit
+Allows you to restrict the number of parallel connections to a server per
+client IP address (or client address block).
+.TP
+\fB\-\-connlimit\-upto\fP \fIn\fP
+Match if the number of existing connections is below or equal \fIn\fP.
+.TP
+\fB\-\-connlimit\-above\fP \fIn\fP
+Match if the number of existing connections is above \fIn\fP.
+.TP
+\fB\-\-connlimit\-mask\fP \fIprefix_length\fP
+Group hosts using the prefix length. For IPv4, this must be a number between
+(including) 0 and 32. For IPv6, between 0 and 128. If not specified, the
+maximum prefix length for the applicable protocol is used.
+.TP
+\fB\-\-connlimit\-saddr\fP
+Apply the limit onto the source group. This is the default if
+\-\-connlimit\-daddr is not specified.
+.TP
+\fB\-\-connlimit\-daddr\fP
+Apply the limit onto the destination group.
+.PP
+Examples:
+.TP
+# allow 2 telnet connections per client host
+iptables \-A INPUT \-p tcp \-\-syn \-\-dport 23 \-m connlimit \-\-connlimit\-above 2 \-j REJECT
+.TP
+# you can also match the other way around:
+iptables \-A INPUT \-p tcp \-\-syn \-\-dport 23 \-m connlimit \-\-connlimit\-upto 2 \-j ACCEPT
+.TP
+# limit the number of parallel HTTP requests to 16 per class C sized \
+source network (24 bit netmask)
+iptables \-p tcp \-\-syn \-\-dport 80 \-m connlimit \-\-connlimit\-above 16
+\-\-connlimit\-mask 24 \-j REJECT
+.TP
+# limit the number of parallel HTTP requests to 16 for the link local network
+(ipv6)
+ip6tables \-p tcp \-\-syn \-\-dport 80 \-s fe80::/64 \-m connlimit \-\-connlimit\-above
+16 \-\-connlimit\-mask 64 \-j REJECT
+.TP
+# Limit the number of connections to a particular host:
+ip6tables \-p tcp \-\-syn \-\-dport 49152:65535 \-d 2001:db8::1 \-m connlimit
+\-\-connlimit-above 100 \-j REJECT
+.SS connmark
+This module matches the netfilter mark field associated with a connection
+(which can be set using the \fBCONNMARK\fP target below).
+.TP
+[\fB!\fP] \fB\-\-mark\fP \fIvalue\fP[\fB/\fP\fImask\fP]
+Matches packets in connections with the given mark value (if a mask is
+specified, this is logically ANDed with the mark before the comparison).
+.SS conntrack
+This module, when combined with connection tracking, allows access to the
+connection tracking state for this packet/connection.
+.TP
+[\fB!\fP] \fB\-\-ctstate\fP \fIstatelist\fP
+\fIstatelist\fP is a comma separated list of the connection states to match.
+Possible states are listed below.
+.TP
+[\fB!\fP] \fB\-\-ctproto\fP \fIl4proto\fP
+Layer-4 protocol to match (by number or name)
+.TP
+[\fB!\fP] \fB\-\-ctorigsrc\fP \fIaddress\fP[\fB/\fP\fImask\fP]
+.TP
+[\fB!\fP] \fB\-\-ctorigdst\fP \fIaddress\fP[\fB/\fP\fImask\fP]
+.TP
+[\fB!\fP] \fB\-\-ctreplsrc\fP \fIaddress\fP[\fB/\fP\fImask\fP]
+.TP
+[\fB!\fP] \fB\-\-ctrepldst\fP \fIaddress\fP[\fB/\fP\fImask\fP]
+Match against original/reply source/destination address
+.TP
+[\fB!\fP] \fB\-\-ctorigsrcport\fP \fIport\fP[\fB:\fP\fIport\fP]
+.TP
+[\fB!\fP] \fB\-\-ctorigdstport\fP \fIport\fP[\fB:\fP\fIport\fP]
+.TP
+[\fB!\fP] \fB\-\-ctreplsrcport\fP \fIport\fP[\fB:\fP\fIport\fP]
+.TP
+[\fB!\fP] \fB\-\-ctrepldstport\fP \fIport\fP[\fB:\fP\fIport\fP]
+Match against original/reply source/destination port (TCP/UDP/etc.) or GRE key.
+Matching against port ranges is only supported in kernel versions above 2.6.38.
+.TP
+[\fB!\fP] \fB\-\-ctstatus\fP \fIstatelist\fP
+\fIstatuslist\fP is a comma separated list of the connection statuses to match.
+Possible statuses are listed below.
+.TP
+[\fB!\fP] \fB\-\-ctexpire\fP \fItime\fP[\fB:\fP\fItime\fP]
+Match remaining lifetime in seconds against given value or range of values
+(inclusive)
+.TP
+\fB\-\-ctdir\fP {\fBORIGINAL\fP|\fBREPLY\fP}
+Match packets that are flowing in the specified direction. If this flag is not
+specified at all, matches packets in both directions.
+.PP
+States for \fB\-\-ctstate\fP:
+.TP
+\fBINVALID\fP
+meaning that the packet is associated with no known connection
+.TP
+\fBNEW\fP
+meaning that the packet has started a new connection, or otherwise associated
+with a connection which has not seen packets in both directions, and
+.TP
+\fBESTABLISHED\fP
+meaning that the packet is associated with a connection which has seen packets
+in both directions,
+.TP
+\fBRELATED\fP
+meaning that the packet is starting a new connection, but is associated with an
+existing connection, such as an FTP data transfer, or an ICMP error.
+.TP
+\fBUNTRACKED\fP
+meaning that the packet is not tracked at all, which happens if you use
+the NOTRACK target in raw table.
+.TP
+\fBSNAT\fP
+A virtual state, matching if the original source address differs from the reply
+destination.
+.TP
+\fBDNAT\fP
+A virtual state, matching if the original destination differs from the reply
+source.
+.PP
+Statuses for \fB\-\-ctstatus\fP:
+.TP
+\fBNONE\fP
+None of the below.
+.TP
+\fBEXPECTED\fP
+This is an expected connection (i.e. a conntrack helper set it up)
+.TP
+\fBSEEN_REPLY\fP
+Conntrack has seen packets in both directions.
+.TP
+\fBASSURED\fP
+Conntrack entry should never be early-expired.
+.TP
+\fBCONFIRMED\fP
+Connection is confirmed: originating packet has left box.
+.SS cpu
+.TP
+[\fB!\fP] \fB\-\-cpu\fP \fInumber\fP
+Match cpu handling this packet. cpus are numbered from 0 to NR_CPUS-1
+Can be used in combination with RPS (Remote Packet Steering) or
+multiqueue NICs to spread network traffic on different queues.
+.PP
+Example:
+.PP
+iptables \-t nat \-A PREROUTING \-p tcp \-\-dport 80 \-m cpu \-\-cpu 0
+\-j REDIRECT \-\-to\-port 8080
+.PP
+iptables \-t nat \-A PREROUTING \-p tcp \-\-dport 80 \-m cpu \-\-cpu 1
+\-j REDIRECT \-\-to\-port 8081
+.PP
+Available since Linux 2.6.36.
+.SS dccp
+.TP
+[\fB!\fP] \fB\-\-source\-port\fP,\fB\-\-sport\fP \fIport\fP[\fB:\fP\fIport\fP]
+.TP
+[\fB!\fP] \fB\-\-destination\-port\fP,\fB\-\-dport\fP \fIport\fP[\fB:\fP\fIport\fP]
+.TP
+[\fB!\fP] \fB\-\-dccp\-types\fP \fImask\fP
+Match when the DCCP packet type is one of 'mask'. 'mask' is a comma-separated
+list of packet types. Packet types are:
+.BR "REQUEST RESPONSE DATA ACK DATAACK CLOSEREQ CLOSE RESET SYNC SYNCACK INVALID" .
+.TP
+[\fB!\fP] \fB\-\-dccp\-option\fP \fInumber\fP
+Match if DCCP option set.
+.SS dscp
+This module matches the 6 bit DSCP field within the TOS field in the
+IP header. DSCP has superseded TOS within the IETF.
+.TP
+[\fB!\fP] \fB\-\-dscp\fP \fIvalue\fP
+Match against a numeric (decimal or hex) value [0-63].
+.TP
+[\fB!\fP] \fB\-\-dscp\-class\fP \fIclass\fP
+Match the DiffServ class. This value may be any of the
+BE, EF, AFxx or CSx classes. It will then be converted
+into its according numeric value.
+.SS dst
+This module matches the parameters in Destination Options header
+.TP
+[\fB!\fP] \fB\-\-dst\-len\fP \fIlength\fP
+Total length of this header in octets.
+.TP
+\fB\-\-dst\-opts\fP \fItype\fP[\fB:\fP\fIlength\fP][\fB,\fP\fItype\fP[\fB:\fP\fIlength\fP]...]
+numeric type of option and the length of the option data in octets.
+.SS ecn
+This allows you to match the ECN bits of the IPv4/IPv6 and TCP header. ECN is the Explicit Congestion Notification mechanism as specified in RFC3168
+.TP
+[\fB!\fP] \fB\-\-ecn\-tcp\-cwr\fP
+This matches if the TCP ECN CWR (Congestion Window Received) bit is set.
+.TP
+[\fB!\fP] \fB\-\-ecn\-tcp\-ece\fP
+This matches if the TCP ECN ECE (ECN Echo) bit is set.
+.TP
+[\fB!\fP] \fB\-\-ecn\-ip\-ect\fP \fInum\fP
+This matches a particular IPv4/IPv6 ECT (ECN-Capable Transport). You have to specify
+a number between `0' and `3'.
+.SS esp
+This module matches the SPIs in ESP header of IPsec packets.
+.TP
+[\fB!\fP] \fB\-\-espspi\fP \fIspi\fP[\fB:\fP\fIspi\fP]
+.SS eui64
+This module matches the EUI-64 part of a stateless autoconfigured IPv6 address.
+It compares the EUI-64 derived from the source MAC address in Ethernet frame
+with the lower 64 bits of the IPv6 source address. But "Universal/Local"
+bit is not compared. This module doesn't match other link layer frame, and
+is only valid in the
+.BR PREROUTING ,
+.BR INPUT
+and
+.BR FORWARD
+chains.
+.SS frag
+This module matches the parameters in Fragment header.
+.TP
+[\fB!\fP] \fB\-\-fragid\fP \fIid\fP[\fB:\fP\fIid\fP]
+Matches the given Identification or range of it.
+.TP
+[\fB!\fP] \fB\-\-fraglen\fP \fIlength\fP
+This option cannot be used with kernel version 2.6.10 or later. The length of
+Fragment header is static and this option doesn't make sense.
+.TP
+\fB\-\-fragres\fP
+Matches if the reserved fields are filled with zero.
+.TP
+\fB\-\-fragfirst\fP
+Matches on the first fragment.
+.TP
+\fB\-\-fragmore\fP
+Matches if there are more fragments.
+.TP
+\fB\-\-fraglast\fP
+Matches if this is the last fragment.
+.SS hashlimit
+\fBhashlimit\fP uses hash buckets to express a rate limiting match (like the
+\fBlimit\fP match) for a group of connections using a \fBsingle\fP iptables
+rule. Grouping can be done per-hostgroup (source and/or destination address)
+and/or per-port. It gives you the ability to express "\fIN\fP packets per time
+quantum per group" (see below for some examples).
+.PP
+A hash limit option (\fB\-\-hashlimit\-upto\fP, \fB\-\-hashlimit\-above\fP) and
+\fB\-\-hashlimit\-name\fP are required.
+.TP
+\fB\-\-hashlimit\-upto\fP \fIamount\fP[\fB/second\fP|\fB/minute\fP|\fB/hour\fP|\fB/day\fP]
+Match if the rate is below or equal to \fIamount\fP/quantum. It is specified as
+a number, with an optional time quantum suffix; the default is 3/hour.
+.TP
+\fB\-\-hashlimit\-above\fP \fIamount\fP[\fB/second\fP|\fB/minute\fP|\fB/hour\fP|\fB/day\fP]
+Match if the rate is above \fIamount\fP/quantum.
+.TP
+\fB\-\-hashlimit\-burst\fP \fIamount\fP
+Maximum initial number of packets to match: this number gets recharged by one
+every time the limit specified above is not reached, up to this number; the
+default is 5.
+.TP
+\fB\-\-hashlimit\-mode\fP {\fBsrcip\fP|\fBsrcport\fP|\fBdstip\fP|\fBdstport\fP}\fB,\fP...
+A comma-separated list of objects to take into consideration. If no
+\-\-hashlimit\-mode option is given, hashlimit acts like limit, but at the
+expensive of doing the hash housekeeping.
+.TP
+\fB\-\-hashlimit\-srcmask\fP \fIprefix\fP
+When \-\-hashlimit\-mode srcip is used, all source addresses encountered will be
+grouped according to the given prefix length and the so-created subnet will be
+subject to hashlimit. \fIprefix\fP must be between (inclusive) 0 and 32. Note
+that \-\-hashlimit\-srcmask 0 is basically doing the same thing as not specifying
+srcip for \-\-hashlimit\-mode, but is technically more expensive.
+.TP
+\fB\-\-hashlimit\-dstmask\fP \fIprefix\fP
+Like \-\-hashlimit\-srcmask, but for destination addresses.
+.TP
+\fB\-\-hashlimit\-name\fP \fIfoo\fP
+The name for the /proc/net/ipt_hashlimit/foo entry.
+.TP
+\fB\-\-hashlimit\-htable\-size\fP \fIbuckets\fP
+The number of buckets of the hash table
+.TP
+\fB\-\-hashlimit\-htable\-max\fP \fIentries\fP
+Maximum entries in the hash.
+.TP
+\fB\-\-hashlimit\-htable\-expire\fP \fImsec\fP
+After how many milliseconds do hash entries expire.
+.TP
+\fB\-\-hashlimit\-htable\-gcinterval\fP \fImsec\fP
+How many milliseconds between garbage collection intervals.
+.PP
+Examples:
+.TP
+matching on source host
+"1000 packets per second for every host in 192.168.0.0/16" =>
+\-s 192.168.0.0/16 \-\-hashlimit\-mode srcip \-\-hashlimit\-upto 1000/sec
+.TP
+matching on source port
+"100 packets per second for every service of 192.168.1.1" =>
+\-s 192.168.1.1 \-\-hashlimit\-mode srcport \-\-hashlimit\-upto 100/sec
+.TP
+matching on subnet
+"10000 packets per minute for every /28 subnet (groups of 8 addresses)
+in 10.0.0.0/8" =>
+\-s 10.0.0.8 \-\-hashlimit\-mask 28 \-\-hashlimit\-upto 10000/min
+.SS hbh
+This module matches the parameters in Hop-by-Hop Options header
+.TP
+[\fB!\fP] \fB\-\-hbh\-len\fP \fIlength\fP
+Total length of this header in octets.
+.TP
+\fB\-\-hbh\-opts\fP \fItype\fP[\fB:\fP\fIlength\fP][\fB,\fP\fItype\fP[\fB:\fP\fIlength\fP]...]
+numeric type of option and the length of the option data in octets.
+.SS helper
+This module matches packets related to a specific conntrack-helper.
+.TP
+[\fB!\fP] \fB\-\-helper\fP \fIstring\fP
+Matches packets related to the specified conntrack-helper.
+.RS
+.PP
+string can be "ftp" for packets related to a ftp-session on default port.
+For other ports append \-portnr to the value, ie. "ftp\-2121".
+.PP
+Same rules apply for other conntrack-helpers.
+.RE
+.SS hl
+This module matches the Hop Limit field in the IPv6 header.
+.TP
+[\fB!\fP] \fB\-\-hl\-eq\fP \fIvalue\fP
+Matches if Hop Limit equals \fIvalue\fP.
+.TP
+\fB\-\-hl\-lt\fP \fIvalue\fP
+Matches if Hop Limit is less than \fIvalue\fP.
+.TP
+\fB\-\-hl\-gt\fP \fIvalue\fP
+Matches if Hop Limit is greater than \fIvalue\fP.
+.SS icmp6
+This extension can be used if `\-\-protocol ipv6\-icmp' or `\-\-protocol icmpv6' is
+specified. It provides the following option:
+.TP
+[\fB!\fP] \fB\-\-icmpv6\-type\fP \fItype\fP[\fB/\fP\fIcode\fP]|\fItypename\fP
+This allows specification of the ICMPv6 type, which can be a numeric
+ICMPv6
+.IR type ,
+.IR type
+and
+.IR code ,
+or one of the ICMPv6 type names shown by the command
+.nf
+ ip6tables \-p ipv6\-icmp \-h
+.fi
+.SS iprange
+This matches on a given arbitrary range of IP addresses.
+.TP
+[\fB!\fP] \fB\-\-src\-range\fP \fIfrom\fP[\fB\-\fP\fIto\fP]
+Match source IP in the specified range.
+.TP
+[\fB!\fP] \fB\-\-dst\-range\fP \fIfrom\fP[\fB\-\fP\fIto\fP]
+Match destination IP in the specified range.
+.SS ipv6header
+This module matches IPv6 extension headers and/or upper layer header.
+.TP
+\fB\-\-soft\fP
+Matches if the packet includes \fBany\fP of the headers specified with
+\fB\-\-header\fP.
+.TP
+[\fB!\fP] \fB\-\-header\fP \fIheader\fP[\fB,\fP\fIheader\fP...]
+Matches the packet which EXACTLY includes all specified headers. The headers
+encapsulated with ESP header are out of scope.
+Possible \fIheader\fP types can be:
+.TP
+\fBhop\fP|\fBhop\-by\-hop\fP
+Hop-by-Hop Options header
+.TP
+\fBdst\fP
+Destination Options header
+.TP
+\fBroute\fP
+Routing header
+.TP
+\fBfrag\fP
+Fragment header
+.TP
+\fBauth\fP
+Authentication header
+.TP
+\fBesp\fP
+Encapsulating Security Payload header
+.TP
+\fBnone\fP
+No Next header which matches 59 in the 'Next Header field' of IPv6 header or
+any IPv6 extension headers
+.TP
+\fBproto\fP
+which matches any upper layer protocol header. A protocol name from
+/etc/protocols and numeric value also allowed. The number 255 is equivalent to
+\fBproto\fP.
+.SS ipvs
+Match IPVS connection properties.
+.TP
+[\fB!\fP] \fB\-\-ipvs\fP
+packet belongs to an IPVS connection
+.TP
+Any of the following options implies \-\-ipvs (even negated)
+.TP
+[\fB!\fP] \fB\-\-vproto\fP \fIprotocol\fP
+VIP protocol to match; by number or name, e.g. "tcp"
+.TP
+[\fB!\fP] \fB\-\-vaddr\fP \fIaddress\fP[\fB/\fP\fImask\fP]
+VIP address to match
+.TP
+[\fB!\fP] \fB\-\-vport\fP \fIport\fP
+VIP port to match; by number or name, e.g. "http"
+.TP
+\fB\-\-vdir\fP {\fBORIGINAL\fP|\fBREPLY\fP}
+flow direction of packet
+.TP
+[\fB!\fP] \fB\-\-vmethod\fP {\fBGATE\fP|\fBIPIP\fP|\fBMASQ\fP}
+IPVS forwarding method used
+.TP
+[\fB!\fP] \fB\-\-vportctl\fP \fIport\fP
+VIP port of the controlling connection to match, e.g. 21 for FTP
+.SS length
+This module matches the length of the layer-3 payload (e.g. layer-4 packet)
+of a packet against a specific value
+or range of values.
+.TP
+[\fB!\fP] \fB\-\-length\fP \fIlength\fP[\fB:\fP\fIlength\fP]
+.SS limit
+This module matches at a limited rate using a token bucket filter.
+A rule using this extension will match until this limit is reached.
+It can be used in combination with the
+.B LOG
+target to give limited logging, for example.
+.PP
+xt_limit has no negation support - you will have to use \-m hashlimit !
+\-\-hashlimit \fIrate\fP in this case whilst omitting \-\-hashlimit\-mode.
+.TP
+\fB\-\-limit\fP \fIrate\fP[\fB/second\fP|\fB/minute\fP|\fB/hour\fP|\fB/day\fP]
+Maximum average matching rate: specified as a number, with an optional
+`/second', `/minute', `/hour', or `/day' suffix; the default is
+3/hour.
+.TP
+\fB\-\-limit\-burst\fP \fInumber\fP
+Maximum initial number of packets to match: this number gets
+recharged by one every time the limit specified above is not reached,
+up to this number; the default is 5.
+.SS mac
+.TP
+[\fB!\fP] \fB\-\-mac\-source\fP \fIaddress\fP
+Match source MAC address. It must be of the form XX:XX:XX:XX:XX:XX.
+Note that this only makes sense for packets coming from an Ethernet device
+and entering the
+.BR PREROUTING ,
+.B FORWARD
+or
+.B INPUT
+chains.
+.SS mark
+This module matches the netfilter mark field associated with a packet
+(which can be set using the
+.B MARK
+target below).
+.TP
+[\fB!\fP] \fB\-\-mark\fP \fIvalue\fP[\fB/\fP\fImask\fP]
+Matches packets with the given unsigned mark value (if a \fImask\fP is
+specified, this is logically ANDed with the \fImask\fP before the
+comparison).
+.SS mh
+This extension is loaded if `\-\-protocol ipv6\-mh' or `\-\-protocol mh' is
+specified. It provides the following option:
+.TP
+[\fB!\fP] \fB\-\-mh\-type\fP \fItype\fP[\fB:\fP\fItype\fP]
+This allows specification of the Mobility Header(MH) type, which can be
+a numeric MH
+.IR type ,
+.IR type
+or one of the MH type names shown by the command
+.nf
+ ip6tables \-p ipv6\-mh \-h
+.fi
+.SS multiport
+This module matches a set of source or destination ports. Up to 15
+ports can be specified. A port range (port:port) counts as two
+ports. It can only be used in conjunction with
+\fB\-p tcp\fP
+or
+\fB\-p udp\fP.
+.TP
+[\fB!\fP] \fB\-\-source\-ports\fP,\fB\-\-sports\fP \fIport\fP[\fB,\fP\fIport\fP|\fB,\fP\fIport\fP\fB:\fP\fIport\fP]...
+Match if the source port is one of the given ports. The flag
+\fB\-\-sports\fP
+is a convenient alias for this option. Multiple ports or port ranges are
+separated using a comma, and a port range is specified using a colon.
+\fB53,1024:65535\fP would therefore match ports 53 and all from 1024 through
+65535.
+.TP
+[\fB!\fP] \fB\-\-destination\-ports\fP,\fB\-\-dports\fP \fIport\fP[\fB,\fP\fIport\fP|\fB,\fP\fIport\fP\fB:\fP\fIport\fP]...
+Match if the destination port is one of the given ports. The flag
+\fB\-\-dports\fP
+is a convenient alias for this option.
+.TP
+[\fB!\fP] \fB\-\-ports\fP \fIport\fP[\fB,\fP\fIport\fP|\fB,\fP\fIport\fP\fB:\fP\fIport\fP]...
+Match if either the source or destination ports are equal to one of
+the given ports.
+.SS nfacct
+The nfacct match provides the extended accounting infrastructure for iptables.
+You have to use this match together with the standalone user-space utility
+.B nfacct(8)
+.PP
+The only option available for this match is the following:
+.TP
+\fB\-\-nfacct\-name\fP \fIname\fP
+This allows you to specify the existing object name that will be use for
+accounting the traffic that this rule-set is matching.
+.PP
+To use this extension, you have to create an accounting object:
+.IP
+nfacct add http\-traffic
+.PP
+Then, you have to attach it to the accounting object via iptables:
+.IP
+iptables \-I INPUT \-p tcp \-\-sport 80 \-m nfacct \-\-nfacct\-name http\-traffic
+.IP
+iptables \-I OUTPUT \-p tcp \-\-dport 80 \-m nfacct \-\-nfacct\-name http\-traffic
+.PP
+Then, you can check for the amount of traffic that the rules match:
+.IP
+nfacct get http\-traffic
+.IP
+{ pkts = 00000000000000000156, bytes = 00000000000000151786 } = http-traffic;
+.PP
+You can obtain
+.B nfacct(8)
+from http://www.netfilter.org or, alternatively, from the git.netfilter.org
+repository.
+.SS owner
+This module attempts to match various characteristics of the packet creator,
+for locally generated packets. This match is only valid in the OUTPUT and
+POSTROUTING chains. Forwarded packets do not have any socket associated with
+them. Packets from kernel threads do have a socket, but usually no owner.
+.TP
+[\fB!\fP] \fB\-\-uid\-owner\fP \fIusername\fP
+.TP
+[\fB!\fP] \fB\-\-uid\-owner\fP \fIuserid\fP[\fB\-\fP\fIuserid\fP]
+Matches if the packet socket's file structure (if it has one) is owned by the
+given user. You may also specify a numerical UID, or an UID range.
+.TP
+[\fB!\fP] \fB\-\-gid\-owner\fP \fIgroupname\fP
+.TP
+[\fB!\fP] \fB\-\-gid\-owner\fP \fIgroupid\fP[\fB\-\fP\fIgroupid\fP]
+Matches if the packet socket's file structure is owned by the given group.
+You may also specify a numerical GID, or a GID range.
+.TP
+[\fB!\fP] \fB\-\-socket\-exists\fP
+Matches if the packet is associated with a socket.
+.SS physdev
+This module matches on the bridge port input and output devices enslaved
+to a bridge device. This module is a part of the infrastructure that enables
+a transparent bridging IP firewall and is only useful for kernel versions
+above version 2.5.44.
+.TP
+[\fB!\fP] \fB\-\-physdev\-in\fP \fIname\fP
+Name of a bridge port via which a packet is received (only for
+packets entering the
+.BR INPUT ,
+.B FORWARD
+and
+.B PREROUTING
+chains). If the interface name ends in a "+", then any
+interface which begins with this name will match. If the packet didn't arrive
+through a bridge device, this packet won't match this option, unless '!' is used.
+.TP
+[\fB!\fP] \fB\-\-physdev\-out\fP \fIname\fP
+Name of a bridge port via which a packet is going to be sent (for packets
+entering the
+.BR FORWARD ,
+.B OUTPUT
+and
+.B POSTROUTING
+chains). If the interface name ends in a "+", then any
+interface which begins with this name will match. Note that in the
+.BR nat " and " mangle
+.B OUTPUT
+chains one cannot match on the bridge output port, however one can in the
+.B "filter OUTPUT"
+chain. If the packet won't leave by a bridge device or if it is yet unknown what
+the output device will be, then the packet won't match this option,
+unless '!' is used.
+.TP
+[\fB!\fP] \fB\-\-physdev\-is\-in\fP
+Matches if the packet has entered through a bridge interface.
+.TP
+[\fB!\fP] \fB\-\-physdev\-is\-out\fP
+Matches if the packet will leave through a bridge interface.
+.TP
+[\fB!\fP] \fB\-\-physdev\-is\-bridged\fP
+Matches if the packet is being bridged and therefore is not being routed.
+This is only useful in the FORWARD and POSTROUTING chains.
+.SS pkttype
+This module matches the link-layer packet type.
+.TP
+[\fB!\fP] \fB\-\-pkt\-type\fP {\fBunicast\fP|\fBbroadcast\fP|\fBmulticast\fP}
+.SS policy
+This modules matches the policy used by IPsec for handling a packet.
+.TP
+\fB\-\-dir\fP {\fBin\fP|\fBout\fP}
+Used to select whether to match the policy used for decapsulation or the
+policy that will be used for encapsulation.
+.B in
+is valid in the
+.B PREROUTING, INPUT and FORWARD
+chains,
+.B out
+is valid in the
+.B POSTROUTING, OUTPUT and FORWARD
+chains.
+.TP
+\fB\-\-pol\fP {\fBnone\fP|\fBipsec\fP}
+Matches if the packet is subject to IPsec processing. \fB\-\-pol none\fP
+cannot be combined with \fB\-\-strict\fP.
+.TP
+\fB\-\-strict\fP
+Selects whether to match the exact policy or match if any rule of
+the policy matches the given policy.
+.PP
+For each policy element that is to be described, one can use one or more of
+the following options. When \fB\-\-strict\fP is in effect, at least one must be
+used per element.
+.TP
+[\fB!\fP] \fB\-\-reqid\fP \fIid\fP
+Matches the reqid of the policy rule. The reqid can be specified with
+.B setkey(8)
+using
+.B unique:id
+as level.
+.TP
+[\fB!\fP] \fB\-\-spi\fP \fIspi\fP
+Matches the SPI of the SA.
+.TP
+[\fB!\fP] \fB\-\-proto\fP {\fBah\fP|\fBesp\fP|\fBipcomp\fP}
+Matches the encapsulation protocol.
+.TP
+[\fB!\fP] \fB\-\-mode\fP {\fBtunnel\fP|\fBtransport\fP}
+Matches the encapsulation mode.
+.TP
+[\fB!\fP] \fB\-\-tunnel\-src\fP \fIaddr\fP[\fB/\fP\fImask\fP]
+Matches the source end-point address of a tunnel mode SA.
+Only valid with \fB\-\-mode tunnel\fP.
+.TP
+[\fB!\fP] \fB\-\-tunnel\-dst\fP \fIaddr\fP[\fB/\fP\fImask\fP]
+Matches the destination end-point address of a tunnel mode SA.
+Only valid with \fB\-\-mode tunnel\fP.
+.TP
+\fB\-\-next\fP
+Start the next element in the policy specification. Can only be used with
+\fB\-\-strict\fP.
+.SS quota
+Implements network quotas by decrementing a byte counter with each
+packet. The condition matches until the byte counter reaches zero. Behavior
+is reversed with negation (i.e. the condition does not match until the
+byte counter reaches zero).
+.TP
+[\fB!\fP] \fB\-\-quota\fP \fIbytes\fP
+The quota in bytes.
+.SS rateest
+The rate estimator can match on estimated rates as collected by the RATEEST
+target. It supports matching on absolute bps/pps values, comparing two rate
+estimators and matching on the difference between two rate estimators.
+.PP
+For a better understanding of the available options, these are all possible
+combinations:
+.\" * Absolute:
+.IP \(bu 4
+\fBrateest\fP \fIoperator\fP \fBrateest-bps\fP
+.IP \(bu 4
+\fBrateest\fP \fIoperator\fP \fBrateest-pps\fP
+.\" * Absolute + Delta:
+.IP \(bu 4
+(\fBrateest\fP minus \fBrateest-bps1\fP) \fIoperator\fP \fBrateest-bps2\fP
+.IP \(bu 4
+(\fBrateest\fP minus \fBrateest-pps1\fP) \fIoperator\fP \fBrateest-pps2\fP
+.\" * Relative:
+.IP \(bu 4
+\fBrateest1\fP \fIoperator\fP \fBrateest2\fP \fBrateest-bps\fP(without rate!)
+.IP \(bu 4
+\fBrateest1\fP \fIoperator\fP \fBrateest2\fP \fBrateest-pps\fP(without rate!)
+.\" * Relative + Delta:
+.IP \(bu 4
+(\fBrateest1\fP minus \fBrateest-bps1\fP) \fIoperator\fP
+(\fBrateest2\fP minus \fBrateest-bps2\fP)
+.IP \(bu 4
+(\fBrateest1\fP minus \fBrateest-pps1\fP) \fIoperator\fP
+(\fBrateest2\fP minus \fBrateest-pps2\fP)
+.TP
+\fB\-\-rateest\-delta\fP
+For each estimator (either absolute or relative mode), calculate the difference
+between the estimator-determined flow rate and the static value chosen with the
+BPS/PPS options. If the flow rate is higher than the specified BPS/PPS, 0 will
+be used instead of a negative value. In other words, "max(0, rateest#_rate -
+rateest#_bps)" is used.
+.TP
+[\fB!\fP] \fB\-\-rateest\-lt\fP
+Match if rate is less than given rate/estimator.
+.TP
+[\fB!\fP] \fB\-\-rateest\-gt\fP
+Match if rate is greater than given rate/estimator.
+.TP
+[\fB!\fP] \fB\-\-rateest\-eq\fP
+Match if rate is equal to given rate/estimator.
+.PP
+In the so-called "absolute mode", only one rate estimator is used and compared
+against a static value, while in "relative mode", two rate estimators are
+compared against another.
+.TP
+\fB\-\-rateest\fP \fIname\fP
+Name of the one rate estimator for absolute mode.
+.TP
+\fB\-\-rateest1\fP \fIname\fP
+.TP
+\fB\-\-rateest2\fP \fIname\fP
+The names of the two rate estimators for relative mode.
+.TP
+\fB\-\-rateest\-bps\fP [\fIvalue\fP]
+.TP
+\fB\-\-rateest\-pps\fP [\fIvalue\fP]
+.TP
+\fB\-\-rateest\-bps1\fP [\fIvalue\fP]
+.TP
+\fB\-\-rateest\-bps2\fP [\fIvalue\fP]
+.TP
+\fB\-\-rateest\-pps1\fP [\fIvalue\fP]
+.TP
+\fB\-\-rateest\-pps2\fP [\fIvalue\fP]
+Compare the estimator(s) by bytes or packets per second, and compare against
+the chosen value. See the above bullet list for which option is to be used in
+which case. A unit suffix may be used - available ones are: bit, [kmgt]bit,
+[KMGT]ibit, Bps, [KMGT]Bps, [KMGT]iBps.
+.PP
+Example: This is what can be used to route outgoing data connections from an
+FTP server over two lines based on the available bandwidth at the time the data
+connection was started:
+.PP
+# Estimate outgoing rates
+.PP
+iptables \-t mangle \-A POSTROUTING \-o eth0 \-j RATEEST \-\-rateest\-name eth0
+\-\-rateest\-interval 250ms \-\-rateest\-ewma 0.5s
+.PP
+iptables \-t mangle \-A POSTROUTING \-o ppp0 \-j RATEEST \-\-rateest\-name ppp0
+\-\-rateest\-interval 250ms \-\-rateest\-ewma 0.5s
+.PP
+# Mark based on available bandwidth
+.PP
+iptables \-t mangle \-A balance \-m conntrack \-\-ctstate NEW \-m helper \-\-helper ftp
+\-m rateest \-\-rateest\-delta \-\-rateest1 eth0 \-\-rateest\-bps1 2.5mbit \-\-rateest\-gt
+\-\-rateest2 ppp0 \-\-rateest\-bps2 2mbit \-j CONNMARK \-\-set\-mark 1
+.PP
+iptables \-t mangle \-A balance \-m conntrack \-\-ctstate NEW \-m helper \-\-helper ftp
+\-m rateest \-\-rateest\-delta \-\-rateest1 ppp0 \-\-rateest\-bps1 2mbit \-\-rateest\-gt
+\-\-rateest2 eth0 \-\-rateest\-bps2 2.5mbit \-j CONNMARK \-\-set\-mark 2
+.PP
+iptables \-t mangle \-A balance \-j CONNMARK \-\-restore\-mark
+.SS recent
+Allows you to dynamically create a list of IP addresses and then match against
+that list in a few different ways.
+.PP
+For example, you can create a "badguy" list out of people attempting to connect
+to port 139 on your firewall and then DROP all future packets from them without
+considering them.
+.PP
+\fB\-\-set\fP, \fB\-\-rcheck\fP, \fB\-\-update\fP and \fB\-\-remove\fP are
+mutually exclusive.
+.TP
+\fB\-\-name\fP \fIname\fP
+Specify the list to use for the commands. If no name is given then
+\fBDEFAULT\fP will be used.
+.TP
+[\fB!\fP] \fB\-\-set\fP
+This will add the source address of the packet to the list. If the source
+address is already in the list, this will update the existing entry. This will
+always return success (or failure if \fB!\fP is passed in).
+.TP
+\fB\-\-rsource\fP
+Match/save the source address of each packet in the recent list table. This
+is the default.
+.TP
+\fB\-\-rdest\fP
+Match/save the destination address of each packet in the recent list table.
+.TP
+[\fB!\fP] \fB\-\-rcheck\fP
+Check if the source address of the packet is currently in the list.
+.TP
+[\fB!\fP] \fB\-\-update\fP
+Like \fB\-\-rcheck\fP, except it will update the "last seen" timestamp if it
+matches.
+.TP
+[\fB!\fP] \fB\-\-remove\fP
+Check if the source address of the packet is currently in the list and if so
+that address will be removed from the list and the rule will return true. If
+the address is not found, false is returned.
+.TP
+\fB\-\-seconds\fP \fIseconds\fP
+This option must be used in conjunction with one of \fB\-\-rcheck\fP or
+\fB\-\-update\fP. When used, this will narrow the match to only happen when the
+address is in the list and was seen within the last given number of seconds.
+.TP
+\fB\-\-reap\fP
+This option can only be used in conjunction with \fB\-\-seconds\fP.
+When used, this will cause entries older than the last given number of seconds
+to be purged.
+.TP
+\fB\-\-hitcount\fP \fIhits\fP
+This option must be used in conjunction with one of \fB\-\-rcheck\fP or
+\fB\-\-update\fP. When used, this will narrow the match to only happen when the
+address is in the list and packets had been received greater than or equal to
+the given value. This option may be used along with \fB\-\-seconds\fP to create
+an even narrower match requiring a certain number of hits within a specific
+time frame. The maximum value for the hitcount parameter is given by the
+"ip_pkt_list_tot" parameter of the xt_recent kernel module. Exceeding this
+value on the command line will cause the rule to be rejected.
+.TP
+\fB\-\-rttl\fP
+This option may only be used in conjunction with one of \fB\-\-rcheck\fP or
+\fB\-\-update\fP. When used, this will narrow the match to only happen when the
+address is in the list and the TTL of the current packet matches that of the
+packet which hit the \fB\-\-set\fP rule. This may be useful if you have problems
+with people faking their source address in order to DoS you via this module by
+disallowing others access to your site by sending bogus packets to you.
+.PP
+Examples:
+.IP
+iptables \-A FORWARD \-m recent \-\-name badguy \-\-rcheck \-\-seconds 60 \-j DROP
+.IP
+iptables \-A FORWARD \-p tcp \-i eth0 \-\-dport 139 \-m recent \-\-name badguy \-\-set \-j DROP
+.PP
+Steve's ipt_recent website (http://snowman.net/projects/ipt_recent/) also has
+some examples of usage.
+.PP
+\fB/proc/net/xt_recent/*\fP are the current lists of addresses and information
+about each entry of each list.
+.PP
+Each file in \fB/proc/net/xt_recent/\fP can be read from to see the current
+list or written two using the following commands to modify the list:
+.TP
+\fBecho +\fP\fIaddr\fP\fB >/proc/net/xt_recent/DEFAULT\fP
+to add \fIaddr\fP to the DEFAULT list
+.TP
+\fBecho \-\fP\fIaddr\fP\fB >/proc/net/xt_recent/DEFAULT\fP
+to remove \fIaddr\fP from the DEFAULT list
+.TP
+\fBecho / >/proc/net/xt_recent/DEFAULT\fP
+to flush the DEFAULT list (remove all entries).
+.PP
+The module itself accepts parameters, defaults shown:
+.TP
+\fBip_list_tot\fP=\fI100\fP
+Number of addresses remembered per table.
+.TP
+\fBip_pkt_list_tot\fP=\fI20\fP
+Number of packets per address remembered.
+.TP
+\fBip_list_hash_size\fP=\fI0\fP
+Hash table size. 0 means to calculate it based on ip_list_tot, default: 512.
+.TP
+\fBip_list_perms\fP=\fI0644\fP
+Permissions for /proc/net/xt_recent/* files.
+.TP
+\fBip_list_uid\fP=\fI0\fP
+Numerical UID for ownership of /proc/net/xt_recent/* files.
+.TP
+\fBip_list_gid\fP=\fI0\fP
+Numerical GID for ownership of /proc/net/xt_recent/* files.
+.SS rpfilter
+Performs a reverse path filter test on a packet.
+If a reply to the packet would be sent via the same interface
+that the packet arrived on, the packet will match.
+Note that, unlike the in-kernel rp_filter, packets protected
+by IPSec are not treated specially. Combine this match with
+the policy match if you want this.
+Also, packets arriving via the loopback interface are always permitted.
+This match can only be used in the PREROUTING chain of the raw or mangle table.
+.TP
+\fB\-\-loose\fP
+Used to specifiy that the reverse path filter test should match
+even if the selected output device is not the expected one.
+.TP
+\fB\-\-validmark\fP
+Also use the packets' nfmark value when performing the reverse path route lookup.
+.TP
+\fB\-\-accept\-local\fP
+This will permit packets arriving from the network with a source address that is also
+assigned to the local machine.
+\fB\-\-invert\fP
+This will invert the sense of the match. Instead of matching packets that passed the
+reverse path filter test, match those that have failed it.
+.PP
+Example to log and drop packets failing the reverse path filter test:
+
+iptables \-t raw \-N RPFILTER
+
+iptables \-t raw \-A RPFILTER \-m rpfilter \-j RETURN
+
+iptables \-t raw \-A RPFILTER \-m limit \-\-limit 10/minute \-j NFLOG \-\-nflog\-prefix "rpfilter drop"
+
+iptables \-t raw \-A RPFILTER \-j DROP
+
+iptables \-t raw \-A PREROUTING \-j RPFILTER
+
+Example to drop failed packets, without logging:
+
+iptables \-t raw \-A RPFILTER \-m rpfilter \-\-invert \-j DROP
+.SS rt
+Match on IPv6 routing header
+.TP
+[\fB!\fP] \fB\-\-rt\-type\fP \fItype\fP
+Match the type (numeric).
+.TP
+[\fB!\fP] \fB\-\-rt\-segsleft\fP \fInum\fP[\fB:\fP\fInum\fP]
+Match the `segments left' field (range).
+.TP
+[\fB!\fP] \fB\-\-rt\-len\fP \fIlength\fP
+Match the length of this header.
+.TP
+\fB\-\-rt\-0\-res\fP
+Match the reserved field, too (type=0)
+.TP
+\fB\-\-rt\-0\-addrs\fP \fIaddr\fP[\fB,\fP\fIaddr\fP...]
+Match type=0 addresses (list).
+.TP
+\fB\-\-rt\-0\-not\-strict\fP
+List of type=0 addresses is not a strict list.
+.SS sctp
+.TP
+[\fB!\fP] \fB\-\-source\-port\fP,\fB\-\-sport\fP \fIport\fP[\fB:\fP\fIport\fP]
+.TP
+[\fB!\fP] \fB\-\-destination\-port\fP,\fB\-\-dport\fP \fIport\fP[\fB:\fP\fIport\fP]
+.TP
+[\fB!\fP] \fB\-\-chunk\-types\fP {\fBall\fP|\fBany\fP|\fBonly\fP} \fIchunktype\fP[\fB:\fP\fIflags\fP] [...]
+The flag letter in upper case indicates that the flag is to match if set,
+in the lower case indicates to match if unset.
+
+Chunk types: DATA INIT INIT_ACK SACK HEARTBEAT HEARTBEAT_ACK ABORT SHUTDOWN SHUTDOWN_ACK ERROR COOKIE_ECHO COOKIE_ACK ECN_ECNE ECN_CWR SHUTDOWN_COMPLETE ASCONF ASCONF_ACK FORWARD_TSN
+
+chunk type available flags
+.br
+DATA I U B E i u b e
+.br
+ABORT T t
+.br
+SHUTDOWN_COMPLETE T t
+
+(lowercase means flag should be "off", uppercase means "on")
+.P
+Examples:
+
+iptables \-A INPUT \-p sctp \-\-dport 80 \-j DROP
+
+iptables \-A INPUT \-p sctp \-\-chunk\-types any DATA,INIT \-j DROP
+
+iptables \-A INPUT \-p sctp \-\-chunk\-types any DATA:Be \-j ACCEPT
+.SS set
+This module matches IP sets which can be defined by ipset(8).
+.TP
+[\fB!\fP] \fB\-\-match\-set\fP \fIsetname\fP \fIflag\fP[\fB,\fP\fIflag\fP]...
+where flags are the comma separated list of
+.BR "src"
+and/or
+.BR "dst"
+specifications and there can be no more than six of them. Hence the command
+.IP
+ iptables \-A FORWARD \-m set \-\-match\-set test src,dst
+.IP
+will match packets, for which (if the set type is ipportmap) the source
+address and destination port pair can be found in the specified set. If
+the set type of the specified set is single dimension (for example ipmap),
+then the command will match packets for which the source address can be
+found in the specified set.
+.PP
+The option \fB\-\-match\-set\fP can be replaced by \fB\-\-set\fP if that does
+not clash with an option of other extensions.
+.PP
+Use of -m set requires that ipset kernel support is provided, which, for
+standard kernels, is the case since Linux 2.6.39.
+.SS socket
+This matches if an open socket can be found by doing a socket lookup on the
+packet.
+.TP
+\fB\-\-transparent\fP
+Ignore non-transparent sockets.
+.SS state
+This module, when combined with connection tracking, allows access to
+the connection tracking state for this packet.
+.TP
+[\fB!\fP] \fB\-\-state\fP \fIstate\fP
+Where state is a comma separated list of the connection states to
+match. Possible states are
+.B INVALID
+meaning that the packet could not be identified for some reason which
+includes running out of memory and ICMP errors which don't correspond to any
+known connection,
+.B ESTABLISHED
+meaning that the packet is associated with a connection which has seen
+packets in both directions,
+.B NEW
+meaning that the packet has started a new connection, or otherwise
+associated with a connection which has not seen packets in both
+directions, and
+.B RELATED
+meaning that the packet is starting a new connection, but is
+associated with an existing connection, such as an FTP data transfer,
+or an ICMP error.
+.B UNTRACKED
+meaning that the packet is not tracked at all, which happens if you use
+the NOTRACK target in raw table.
+.SS statistic
+This module matches packets based on some statistic condition.
+It supports two distinct modes settable with the
+\fB\-\-mode\fP
+option.
+.PP
+Supported options:
+.TP
+\fB\-\-mode\fP \fImode\fP
+Set the matching mode of the matching rule, supported modes are
+.B random
+and
+.B nth.
+.TP
+[\fB!\fP] \fB\-\-probability\fP \fIp\fP
+Set the probability for a packet to be randomly matched. It only works with the
+\fBrandom\fP mode. \fIp\fP must be within 0.0 and 1.0. The supported
+granularity is in 1/2147483648th increments.
+.TP
+[\fB!\fP] \fB\-\-every\fP \fIn\fP
+Match one packet every nth packet. It works only with the
+.B nth
+mode (see also the
+\fB\-\-packet\fP
+option).
+.TP
+\fB\-\-packet\fP \fIp\fP
+Set the initial counter value (0 <= p <= n\-1, default 0) for the
+.B nth
+mode.
+.SS string
+This modules matches a given string by using some pattern matching strategy. It requires a linux kernel >= 2.6.14.
+.TP
+\fB\-\-algo\fP {\fBbm\fP|\fBkmp\fP}
+Select the pattern matching strategy. (bm = Boyer-Moore, kmp = Knuth-Pratt-Morris)
+.TP
+\fB\-\-from\fP \fIoffset\fP
+Set the offset from which it starts looking for any matching. If not passed, default is 0.
+.TP
+\fB\-\-to\fP \fIoffset\fP
+Set the offset up to which should be scanned. That is, byte \fIoffset\fP-1
+(counting from 0) is the last one that is scanned.
+If not passed, default is the packet size.
+.TP
+[\fB!\fP] \fB\-\-string\fP \fIpattern\fP
+Matches the given pattern.
+.TP
+[\fB!\fP] \fB\-\-hex\-string\fP \fIpattern\fP
+Matches the given pattern in hex notation.
+.SS tcp
+These extensions can be used if `\-\-protocol tcp' is specified. It
+provides the following options:
+.TP
+[\fB!\fP] \fB\-\-source\-port\fP,\fB\-\-sport\fP \fIport\fP[\fB:\fP\fIport\fP]
+Source port or port range specification. This can either be a service
+name or a port number. An inclusive range can also be specified,
+using the format \fIfirst\fP\fB:\fP\fIlast\fP.
+If the first port is omitted, "0" is assumed; if the last is omitted,
+"65535" is assumed.
+If the first port is greater than the second one they will be swapped.
+The flag
+\fB\-\-sport\fP
+is a convenient alias for this option.
+.TP
+[\fB!\fP] \fB\-\-destination\-port\fP,\fB\-\-dport\fP \fIport\fP[\fB:\fP\fIport\fP]
+Destination port or port range specification. The flag
+\fB\-\-dport\fP
+is a convenient alias for this option.
+.TP
+[\fB!\fP] \fB\-\-tcp\-flags\fP \fImask\fP \fIcomp\fP
+Match when the TCP flags are as specified. The first argument \fImask\fP is the
+flags which we should examine, written as a comma-separated list, and
+the second argument \fIcomp\fP is a comma-separated list of flags which must be
+set. Flags are:
+.BR "SYN ACK FIN RST URG PSH ALL NONE" .
+Hence the command
+.nf
+ iptables \-A FORWARD \-p tcp \-\-tcp\-flags SYN,ACK,FIN,RST SYN
+.fi
+will only match packets with the SYN flag set, and the ACK, FIN and
+RST flags unset.
+.TP
+[\fB!\fP] \fB\-\-syn\fP
+Only match TCP packets with the SYN bit set and the ACK,RST and FIN bits
+cleared. Such packets are used to request TCP connection initiation;
+for example, blocking such packets coming in an interface will prevent
+incoming TCP connections, but outgoing TCP connections will be
+unaffected.
+It is equivalent to \fB\-\-tcp\-flags SYN,RST,ACK,FIN SYN\fP.
+If the "!" flag precedes the "\-\-syn", the sense of the
+option is inverted.
+.TP
+[\fB!\fP] \fB\-\-tcp\-option\fP \fInumber\fP
+Match if TCP option set.
+.SS tcpmss
+This matches the TCP MSS (maximum segment size) field of the TCP header. You can only use this on TCP SYN or SYN/ACK packets, since the MSS is only negotiated during the TCP handshake at connection startup time.
+.TP
+[\fB!\fP] \fB\-\-mss\fP \fIvalue\fP[\fB:\fP\fIvalue\fP]
+Match a given TCP MSS value or range.
+.SS time
+This matches if the packet arrival time/date is within a given range. All
+options are optional, but are ANDed when specified. All times are interpreted
+as UTC by default.
+.TP
+\fB\-\-datestart\fP \fIYYYY\fP[\fB\-\fP\fIMM\fP[\fB\-\fP\fIDD\fP[\fBT\fP\fIhh\fP[\fB:\fP\fImm\fP[\fB:\fP\fIss\fP]]]]]
+.TP
+\fB\-\-datestop\fP \fIYYYY\fP[\fB\-\fP\fIMM\fP[\fB\-\fP\fIDD\fP[\fBT\fP\fIhh\fP[\fB:\fP\fImm\fP[\fB:\fP\fIss\fP]]]]]
+Only match during the given time, which must be in ISO 8601 "T" notation.
+The possible time range is 1970-01-01T00:00:00 to 2038-01-19T04:17:07.
+.IP
+If \-\-datestart or \-\-datestop are not specified, it will default to 1970-01-01
+and 2038-01-19, respectively.
+.TP
+\fB\-\-timestart\fP \fIhh\fP\fB:\fP\fImm\fP[\fB:\fP\fIss\fP]
+.TP
+\fB\-\-timestop\fP \fIhh\fP\fB:\fP\fImm\fP[\fB:\fP\fIss\fP]
+Only match during the given daytime. The possible time range is 00:00:00 to
+23:59:59. Leading zeroes are allowed (e.g. "06:03") and correctly interpreted
+as base-10.
+.TP
+[\fB!\fP] \fB\-\-monthdays\fP \fIday\fP[\fB,\fP\fIday\fP...]
+Only match on the given days of the month. Possible values are \fB1\fP
+to \fB31\fP. Note that specifying \fB31\fP will of course not match
+on months which do not have a 31st day; the same goes for 28- or 29-day
+February.
+.TP
+[\fB!\fP] \fB\-\-weekdays\fP \fIday\fP[\fB,\fP\fIday\fP...]
+Only match on the given weekdays. Possible values are \fBMon\fP, \fBTue\fP,
+\fBWed\fP, \fBThu\fP, \fBFri\fP, \fBSat\fP, \fBSun\fP, or values from \fB1\fP
+to \fB7\fP, respectively. You may also use two-character variants (\fBMo\fP,
+\fBTu\fP, etc.).
+.TP
+\fB\-\-kerneltz\fP
+Use the kernel timezone instead of UTC to determine whether a packet meets the
+time regulations.
+.PP
+About kernel timezones: Linux keeps the system time in UTC, and always does so.
+On boot, system time is initialized from a referential time source. Where this
+time source has no timezone information, such as the x86 CMOS RTC, UTC will be
+assumed. If the time source is however not in UTC, userspace should provide the
+correct system time and timezone to the kernel once it has the information.
+.PP
+Local time is a feature on top of the (timezone independent) system time. Each
+process has its own idea of local time, specified via the TZ environment
+variable. The kernel also has its own timezone offset variable. The TZ
+userspace environment variable specifies how the UTC-based system time is
+displayed, e.g. when you run date(1), or what you see on your desktop clock.
+The TZ string may resolve to different offsets at different dates, which is
+what enables the automatic time-jumping in userspace. when DST changes. The
+kernel's timezone offset variable is used when it has to convert between
+non-UTC sources, such as FAT filesystems, to UTC (since the latter is what the
+rest of the system uses).
+.PP
+The caveat with the kernel timezone is that Linux distributions may ignore to
+set the kernel timezone, and instead only set the system time. Even if a
+particular distribution does set the timezone at boot, it is usually does not
+keep the kernel timezone offset - which is what changes on DST - up to date.
+ntpd will not touch the kernel timezone, so running it will not resolve the
+issue. As such, one may encounter a timezone that is always +0000, or one that
+is wrong half of the time of the year. As such, \fBusing \-\-kerneltz is highly
+discouraged.\fP
+.PP
+EXAMPLES. To match on weekends, use:
+.IP
+\-m time \-\-weekdays Sa,Su
+.PP
+Or, to match (once) on a national holiday block:
+.IP
+\-m time \-\-datestart 2007\-12\-24 \-\-datestop 2007\-12\-27
+.PP
+Since the stop time is actually inclusive, you would need the following stop
+time to not match the first second of the new day:
+.IP
+\-m time \-\-datestart 2007\-01\-01T17:00 \-\-datestop 2007\-01\-01T23:59:59
+.PP
+During lunch hour:
+.IP
+\-m time \-\-timestart 12:30 \-\-timestop 13:30
+.PP
+The fourth Friday in the month:
+.IP
+\-m time \-\-weekdays Fr \-\-monthdays 22,23,24,25,26,27,28
+.PP
+(Note that this exploits a certain mathematical property. It is not possible to
+say "fourth Thursday OR fourth Friday" in one rule. It is possible with
+multiple rules, though.)
+.SS tos
+This module matches the 8-bit Type of Service field in the IPv4 header (i.e.
+including the "Precedence" bits) or the (also 8-bit) Priority field in the IPv6
+header.
+.TP
+[\fB!\fP] \fB\-\-tos\fP \fIvalue\fP[\fB/\fP\fImask\fP]
+Matches packets with the given TOS mark value. If a mask is specified, it is
+logically ANDed with the TOS mark before the comparison.
+.TP
+[\fB!\fP] \fB\-\-tos\fP \fIsymbol\fP
+You can specify a symbolic name when using the tos match for IPv4. The list of
+recognized TOS names can be obtained by calling iptables with \fB\-m tos \-h\fP.
+Note that this implies a mask of 0x3F, i.e. all but the ECN bits.
+.SS u32
+U32 tests whether quantities of up to 4 bytes extracted from a packet have
+specified values. The specification of what to extract is general enough to
+find data at given offsets from tcp headers or payloads.
+.TP
+[\fB!\fP] \fB\-\-u32\fP \fItests\fP
+The argument amounts to a program in a small language described below.
+.IP
+tests := location "=" value | tests "&&" location "=" value
+.IP
+value := range | value "," range
+.IP
+range := number | number ":" number
+.PP
+a single number, \fIn\fP, is interpreted the same as \fIn:n\fP. \fIn:m\fP is
+interpreted as the range of numbers \fB>=n\fP and \fB<=m\fP.
+.IP "" 4
+location := number | location operator number
+.IP "" 4
+operator := "&" | "<<" | ">>" | "@"
+.PP
+The operators \fB&\fP, \fB<<\fP, \fB>>\fP and \fB&&\fP mean the same as in C.
+The \fB=\fP is really a set membership operator and the value syntax describes
+a set. The \fB@\fP operator is what allows moving to the next header and is
+described further below.
+.PP
+There are currently some artificial implementation limits on the size of the
+tests:
+.IP " *"
+no more than 10 of "\fB=\fP" (and 9 "\fB&&\fP"s) in the u32 argument
+.IP " *"
+no more than 10 ranges (and 9 commas) per value
+.IP " *"
+no more than 10 numbers (and 9 operators) per location
+.PP
+To describe the meaning of location, imagine the following machine that
+interprets it. There are three registers:
+.IP
+A is of type \fBchar *\fP, initially the address of the IP header
+.IP
+B and C are unsigned 32 bit integers, initially zero
+.PP
+The instructions are:
+.IP
+number B = number;
+.IP
+C = (*(A+B)<<24) + (*(A+B+1)<<16) + (*(A+B+2)<<8) + *(A+B+3)
+.IP
+&number C = C & number
+.IP
+<< number C = C << number
+.IP
+>> number C = C >> number
+.IP
+@number A = A + C; then do the instruction number
+.PP
+Any access of memory outside [skb\->data,skb\->end] causes the match to fail.
+Otherwise the result of the computation is the final value of C.
+.PP
+Whitespace is allowed but not required in the tests. However, the characters
+that do occur there are likely to require shell quoting, so it is a good idea
+to enclose the arguments in quotes.
+.PP
+Example:
+.IP
+match IP packets with total length >= 256
+.IP
+The IP header contains a total length field in bytes 2-3.
+.IP
+\-\-u32 "\fB0 & 0xFFFF = 0x100:0xFFFF\fP"
+.IP
+read bytes 0-3
+.IP
+AND that with 0xFFFF (giving bytes 2-3), and test whether that is in the range
+[0x100:0xFFFF]
+.PP
+Example: (more realistic, hence more complicated)
+.IP
+match ICMP packets with icmp type 0
+.IP
+First test that it is an ICMP packet, true iff byte 9 (protocol) = 1
+.IP
+\-\-u32 "\fB6 & 0xFF = 1 &&\fP ...
+.IP
+read bytes 6-9, use \fB&\fP to throw away bytes 6-8 and compare the result to
+1. Next test that it is not a fragment. (If so, it might be part of such a
+packet but we cannot always tell.) N.B.: This test is generally needed if you
+want to match anything beyond the IP header. The last 6 bits of byte 6 and all
+of byte 7 are 0 iff this is a complete packet (not a fragment). Alternatively,
+you can allow first fragments by only testing the last 5 bits of byte 6.
+.IP
+ ... \fB4 & 0x3FFF = 0 &&\fP ...
+.IP
+Last test: the first byte past the IP header (the type) is 0. This is where we
+have to use the @syntax. The length of the IP header (IHL) in 32 bit words is
+stored in the right half of byte 0 of the IP header itself.
+.IP
+ ... \fB0 >> 22 & 0x3C @ 0 >> 24 = 0\fP"
+.IP
+The first 0 means read bytes 0-3, \fB>>22\fP means shift that 22 bits to the
+right. Shifting 24 bits would give the first byte, so only 22 bits is four
+times that plus a few more bits. \fB&3C\fP then eliminates the two extra bits
+on the right and the first four bits of the first byte. For instance, if IHL=5,
+then the IP header is 20 (4 x 5) bytes long. In this case, bytes 0-1 are (in
+binary) xxxx0101 yyzzzzzz, \fB>>22\fP gives the 10 bit value xxxx0101yy and
+\fB&3C\fP gives 010100. \fB@\fP means to use this number as a new offset into
+the packet, and read four bytes starting from there. This is the first 4 bytes
+of the ICMP payload, of which byte 0 is the ICMP type. Therefore, we simply
+shift the value 24 to the right to throw out all but the first byte and compare
+the result with 0.
+.PP
+Example:
+.IP
+TCP payload bytes 8-12 is any of 1, 2, 5 or 8
+.IP
+First we test that the packet is a tcp packet (similar to ICMP).
+.IP
+\-\-u32 "\fB6 & 0xFF = 6 &&\fP ...
+.IP
+Next, test that it is not a fragment (same as above).
+.IP
+ ... \fB0 >> 22 & 0x3C @ 12 >> 26 & 0x3C @ 8 = 1,2,5,8\fP"
+.IP
+\fB0>>22&3C\fP as above computes the number of bytes in the IP header. \fB@\fP
+makes this the new offset into the packet, which is the start of the TCP
+header. The length of the TCP header (again in 32 bit words) is the left half
+of byte 12 of the TCP header. The \fB12>>26&3C\fP computes this length in bytes
+(similar to the IP header before). "@" makes this the new offset, which is the
+start of the TCP payload. Finally, 8 reads bytes 8-12 of the payload and
+\fB=\fP checks whether the result is any of 1, 2, 5 or 8.
+.SS udp
+These extensions can be used if `\-\-protocol udp' is specified. It
+provides the following options:
+.TP
+[\fB!\fP] \fB\-\-source\-port\fP,\fB\-\-sport\fP \fIport\fP[\fB:\fP\fIport\fP]
+Source port or port range specification.
+See the description of the
+\fB\-\-source\-port\fP
+option of the TCP extension for details.
+.TP
+[\fB!\fP] \fB\-\-destination\-port\fP,\fB\-\-dport\fP \fIport\fP[\fB:\fP\fIport\fP]
+Destination port or port range specification.
+See the description of the
+\fB\-\-destination\-port\fP
+option of the TCP extension for details.
+.SH TARGET EXTENSIONS
+ip6tables can use extended target modules: the following are included
+in the standard distribution.
+.\" @TARGET@
+.SS AUDIT
+This target allows to create audit records for packets hitting the target.
+It can be used to record accepted, dropped, and rejected packets. See
+auditd(8) for additional details.
+.TP
+\fB\-\-type\fP {\fBaccept\fP|\fBdrop\fP|\fBreject\fP}
+Set type of audit record.
+.PP
+Example:
+.IP
+iptables \-N AUDIT_DROP
+.IP
+iptables \-A AUDIT_DROP \-j AUDIT \-\-type drop
+.IP
+iptables \-A AUDIT_DROP \-j DROP
+.SS CHECKSUM
+This target allows to selectively work around broken/old applications.
+It can only be used in the mangle table.
+.TP
+\fB\-\-checksum\-fill\fP
+Compute and fill in the checksum in a packet that lacks a checksum.
+This is particularly useful, if you need to work around old applications
+such as dhcp clients, that do not work well with checksum offloads,
+but don't want to disable checksum offload in your device.
+.SS CLASSIFY
+This module allows you to set the skb\->priority value (and thus classify the packet into a specific CBQ class).
+.TP
+\fB\-\-set\-class\fP \fImajor\fP\fB:\fP\fIminor\fP
+Set the major and minor class value. The values are always interpreted as
+hexadecimal even if no 0x prefix is given.
+.SS CONNMARK
+This module sets the netfilter mark value associated with a connection. The
+mark is 32 bits wide.
+.TP
+\fB\-\-set\-xmark\fP \fIvalue\fP[\fB/\fP\fImask\fP]
+Zero out the bits given by \fImask\fP and XOR \fIvalue\fP into the ctmark.
+.TP
+\fB\-\-save\-mark\fP [\fB\-\-nfmask\fP \fInfmask\fP] [\fB\-\-ctmask\fP \fIctmask\fP]
+Copy the packet mark (nfmark) to the connection mark (ctmark) using the given
+masks. The new nfmark value is determined as follows:
+.IP
+ctmark = (ctmark & ~ctmask) ^ (nfmark & nfmask)
+.IP
+i.e. \fIctmask\fP defines what bits to clear and \fInfmask\fP what bits of the
+nfmark to XOR into the ctmark. \fIctmask\fP and \fInfmask\fP default to
+0xFFFFFFFF.
+.TP
+\fB\-\-restore\-mark\fP [\fB\-\-nfmask\fP \fInfmask\fP] [\fB\-\-ctmask\fP \fIctmask\fP]
+Copy the connection mark (ctmark) to the packet mark (nfmark) using the given
+masks. The new ctmark value is determined as follows:
+.IP
+nfmark = (nfmark & ~\fInfmask\fP) ^ (ctmark & \fIctmask\fP);
+.IP
+i.e. \fInfmask\fP defines what bits to clear and \fIctmask\fP what bits of the
+ctmark to XOR into the nfmark. \fIctmask\fP and \fInfmask\fP default to
+0xFFFFFFFF.
+.IP
+\fB\-\-restore\-mark\fP is only valid in the \fBmangle\fP table.
+.PP
+The following mnemonics are available for \fB\-\-set\-xmark\fP:
+.TP
+\fB\-\-and\-mark\fP \fIbits\fP
+Binary AND the ctmark with \fIbits\fP. (Mnemonic for \fB\-\-set\-xmark
+0/\fP\fIinvbits\fP, where \fIinvbits\fP is the binary negation of \fIbits\fP.)
+.TP
+\fB\-\-or\-mark\fP \fIbits\fP
+Binary OR the ctmark with \fIbits\fP. (Mnemonic for \fB\-\-set\-xmark\fP
+\fIbits\fP\fB/\fP\fIbits\fP.)
+.TP
+\fB\-\-xor\-mark\fP \fIbits\fP
+Binary XOR the ctmark with \fIbits\fP. (Mnemonic for \fB\-\-set\-xmark\fP
+\fIbits\fP\fB/0\fP.)
+.TP
+\fB\-\-set\-mark\fP \fIvalue\fP[\fB/\fP\fImask\fP]
+Set the connection mark. If a mask is specified then only those bits set in the
+mask are modified.
+.TP
+\fB\-\-save\-mark\fP [\fB\-\-mask\fP \fImask\fP]
+Copy the nfmark to the ctmark. If a mask is specified, only those bits are
+copied.
+.TP
+\fB\-\-restore\-mark\fP [\fB\-\-mask\fP \fImask\fP]
+Copy the ctmark to the nfmark. If a mask is specified, only those bits are
+copied. This is only valid in the \fBmangle\fP table.
+.SS CONNSECMARK
+This module copies security markings from packets to connections
+(if unlabeled), and from connections back to packets (also only
+if unlabeled). Typically used in conjunction with SECMARK, it is
+valid in the
+.B security
+table (for backwards compatibility with older kernels, it is also
+valid in the
+.B mangle
+table).
+.TP
+\fB\-\-save\fP
+If the packet has a security marking, copy it to the connection
+if the connection is not marked.
+.TP
+\fB\-\-restore\fP
+If the packet does not have a security marking, and the connection
+does, copy the security marking from the connection to the packet.
+
+.SS CT
+The CT target allows to set parameters for a packet or its associated
+connection. The target attaches a "template" connection tracking entry to
+the packet, which is then used by the conntrack core when initializing
+a new ct entry. This target is thus only valid in the "raw" table.
+.TP
+\fB\-\-notrack\fP
+Disables connection tracking for this packet.
+.TP
+\fB\-\-helper\fP \fIname\fP
+Use the helper identified by \fIname\fP for the connection. This is more
+flexible than loading the conntrack helper modules with preset ports.
+.TP
+\fB\-\-ctevents\fP \fIevent\fP[\fB,\fP...]
+Only generate the specified conntrack events for this connection. Possible
+event types are: \fBnew\fP, \fBrelated\fP, \fBdestroy\fP, \fBreply\fP,
+\fBassured\fP, \fBprotoinfo\fP, \fBhelper\fP, \fBmark\fP (this refers to
+the ctmark, not nfmark), \fBnatseqinfo\fP, \fBsecmark\fP (ctsecmark).
+.TP
+\fB\-\-expevents\fP \fIevent\fP[\fB,\fP...]
+Only generate the specified expectation events for this connection.
+Possible event types are: \fBnew\fP.
+.TP
+\fB\-\-zone\fP \fIid\fP
+Assign this packet to zone \fIid\fP and only have lookups done in that zone.
+By default, packets have zone 0.
+.SS DSCP
+This target allows to alter the value of the DSCP bits within the TOS
+header of the IPv4 packet. As this manipulates a packet, it can only
+be used in the mangle table.
+.TP
+\fB\-\-set\-dscp\fP \fIvalue\fP
+Set the DSCP field to a numerical value (can be decimal or hex)
+.TP
+\fB\-\-set\-dscp\-class\fP \fIclass\fP
+Set the DSCP field to a DiffServ class.
+.SS HL
+This is used to modify the Hop Limit field in IPv6 header. The Hop Limit field
+is similar to what is known as TTL value in IPv4. Setting or incrementing the
+Hop Limit field can potentially be very dangerous, so it should be avoided at
+any cost. This target is only valid in
+.B mangle
+table.
+.PP
+.B Don't ever set or increment the value on packets that leave your local network!
+.TP
+\fB\-\-hl\-set\fP \fIvalue\fP
+Set the Hop Limit to `value'.
+.TP
+\fB\-\-hl\-dec\fP \fIvalue\fP
+Decrement the Hop Limit `value' times.
+.TP
+\fB\-\-hl\-inc\fP \fIvalue\fP
+Increment the Hop Limit `value' times.
+.SS IDLETIMER
+This target can be used to identify when interfaces have been idle for a
+certain period of time. Timers are identified by labels and are created when
+a rule is set with a new label. The rules also take a timeout value (in
+seconds) as an option. If more than one rule uses the same timer label, the
+timer will be restarted whenever any of the rules get a hit. One entry for
+each timer is created in sysfs. This attribute contains the timer remaining
+for the timer to expire. The attributes are located under the xt_idletimer
+class:
+.PP
+/sys/class/xt_idletimer/timers/<label>
+.PP
+When the timer expires, the target module sends a sysfs notification to the
+userspace, which can then decide what to do (eg. disconnect to save power).
+.TP
+\fB\-\-timeout\fP \fIamount\fP
+This is the time in seconds that will trigger the notification.
+.TP
+\fB\-\-label\fP \fIstring\fP
+This is a unique identifier for the timer. The maximum length for the
+label string is 27 characters.
+.SS LOG
+Turn on kernel logging of matching packets. When this option is set
+for a rule, the Linux kernel will print some information on all
+matching packets (like most IPv6 IPv6-header fields) via the kernel log
+(where it can be read with
+.I dmesg
+or
+.IR syslogd (8)).
+This is a "non-terminating target", i.e. rule traversal continues at
+the next rule. So if you want to LOG the packets you refuse, use two
+separate rules with the same matching criteria, first using target LOG
+then DROP (or REJECT).
+.TP
+\fB\-\-log\-level\fP \fIlevel\fP
+Level of logging (numeric or see \fIsyslog.conf\fP(5)).
+.TP
+\fB\-\-log\-prefix\fP \fIprefix\fP
+Prefix log messages with the specified prefix; up to 29 letters long,
+and useful for distinguishing messages in the logs.
+.TP
+\fB\-\-log\-tcp\-sequence\fP
+Log TCP sequence numbers. This is a security risk if the log is
+readable by users.
+.TP
+\fB\-\-log\-tcp\-options\fP
+Log options from the TCP packet header.
+.TP
+\fB\-\-log\-ip\-options\fP
+Log options from the IPv6 packet header.
+.TP
+\fB\-\-log\-uid\fP
+Log the userid of the process which generated the packet.
+.SS MARK
+This target is used to set the Netfilter mark value associated with the packet.
+It can, for example, be used in conjunction with routing based on fwmark (needs
+iproute2). If you plan on doing so, note that the mark needs to be set in the
+PREROUTING chain of the mangle table to affect routing.
+The mark field is 32 bits wide.
+.TP
+\fB\-\-set\-xmark\fP \fIvalue\fP[\fB/\fP\fImask\fP]
+Zeroes out the bits given by \fImask\fP and XORs \fIvalue\fP into the packet
+mark ("nfmark"). If \fImask\fP is omitted, 0xFFFFFFFF is assumed.
+.TP
+\fB\-\-set\-mark\fP \fIvalue\fP[\fB/\fP\fImask\fP]
+Zeroes out the bits given by \fImask\fP and ORs \fIvalue\fP into the packet
+mark. If \fImask\fP is omitted, 0xFFFFFFFF is assumed.
+.PP
+The following mnemonics are available:
+.TP
+\fB\-\-and\-mark\fP \fIbits\fP
+Binary AND the nfmark with \fIbits\fP. (Mnemonic for \fB\-\-set\-xmark
+0/\fP\fIinvbits\fP, where \fIinvbits\fP is the binary negation of \fIbits\fP.)
+.TP
+\fB\-\-or\-mark\fP \fIbits\fP
+Binary OR the nfmark with \fIbits\fP. (Mnemonic for \fB\-\-set\-xmark\fP
+\fIbits\fP\fB/\fP\fIbits\fP.)
+.TP
+\fB\-\-xor\-mark\fP \fIbits\fP
+Binary XOR the nfmark with \fIbits\fP. (Mnemonic for \fB\-\-set\-xmark\fP
+\fIbits\fP\fB/0\fP.)
+.SS NFLOG
+This target provides logging of matching packets. When this target is
+set for a rule, the Linux kernel will pass the packet to the loaded
+logging backend to log the packet. This is usually used in combination
+with nfnetlink_log as logging backend, which will multicast the packet
+through a
+.IR netlink
+socket to the specified multicast group. One or more userspace processes
+may subscribe to the group to receive the packets. Like LOG, this is a
+non-terminating target, i.e. rule traversal continues at the next rule.
+.TP
+\fB\-\-nflog\-group\fP \fInlgroup\fP
+The netlink group (0 - 2^16\-1) to which packets are (only applicable for
+nfnetlink_log). The default value is 0.
+.TP
+\fB\-\-nflog\-prefix\fP \fIprefix\fP
+A prefix string to include in the log message, up to 64 characters
+long, useful for distinguishing messages in the logs.
+.TP
+\fB\-\-nflog\-range\fP \fIsize\fP
+The number of bytes to be copied to userspace (only applicable for
+nfnetlink_log). nfnetlink_log instances may specify their own
+range, this option overrides it.
+.TP
+\fB\-\-nflog\-threshold\fP \fIsize\fP
+Number of packets to queue inside the kernel before sending them
+to userspace (only applicable for nfnetlink_log). Higher values
+result in less overhead per packet, but increase delay until the
+packets reach userspace. The default value is 1.
+.BR
+.SS NFQUEUE
+This target is an extension of the QUEUE target. As opposed to QUEUE, it allows
+you to put a packet into any specific queue, identified by its 16-bit queue
+number.
+It can only be used with Kernel versions 2.6.14 or later, since it requires
+the
+.B
+nfnetlink_queue
+kernel support. The \fBqueue-balance\fP option was added in Linux 2.6.31,
+\fBqueue-bypass\fP in 2.6.39.
+.TP
+\fB\-\-queue\-num\fP \fIvalue\fP
+This specifies the QUEUE number to use. Valid queue numbers are 0 to 65535. The default value is 0.
+.PP
+.TP
+\fB\-\-queue\-balance\fP \fIvalue\fP\fB:\fP\fIvalue\fP
+This specifies a range of queues to use. Packets are then balanced across the given queues.
+This is useful for multicore systems: start multiple instances of the userspace program on
+queues x, x+1, .. x+n and use "\-\-queue\-balance \fIx\fP\fB:\fP\fIx+n\fP".
+Packets belonging to the same connection are put into the same nfqueue.
+.PP
+.TP
+\fB\-\-queue\-bypass\fP
+By default, if no userspace program is listening on an NFQUEUE, then all packets that are to be queued
+are dropped. When this option is used, the NFQUEUE rule is silently bypassed instead. The packet
+will move on to the next rule.
+.SS NOTRACK
+This target disables connection tracking for all packets matching that rule.
+.PP
+It can only be used in the
+.B raw
+table.
+.SS RATEEST
+The RATEEST target collects statistics, performs rate estimation calculation
+and saves the results for later evaluation using the \fBrateest\fP match.
+.TP
+\fB\-\-rateest\-name\fP \fIname\fP
+Count matched packets into the pool referred to by \fIname\fP, which is freely
+choosable.
+.TP
+\fB\-\-rateest\-interval\fP \fIamount\fP{\fBs\fP|\fBms\fP|\fBus\fP}
+Rate measurement interval, in seconds, milliseconds or microseconds.
+.TP
+\fB\-\-rateest\-ewmalog\fP \fIvalue\fP
+Rate measurement averaging time constant.
+.SS REJECT
+This is used to send back an error packet in response to the matched
+packet: otherwise it is equivalent to
+.B DROP
+so it is a terminating TARGET, ending rule traversal.
+This target is only valid in the
+.BR INPUT ,
+.B FORWARD
+and
+.B OUTPUT
+chains, and user-defined chains which are only called from those
+chains. The following option controls the nature of the error packet
+returned:
+.TP
+\fB\-\-reject\-with\fP \fItype\fP
+The type given can be
+\fBicmp6\-no\-route\fP,
+\fBno\-route\fP,
+\fBicmp6\-adm\-prohibited\fP,
+\fBadm\-prohibited\fP,
+\fBicmp6\-addr\-unreachable\fP,
+\fBaddr\-unreach\fP,
+\fBicmp6\-port\-unreachable\fP or
+\fBport\-unreach\fP
+which return the appropriate ICMPv6 error message (\fBport\-unreach\fP is
+the default). Finally, the option
+\fBtcp\-reset\fP
+can be used on rules which only match the TCP protocol: this causes a
+TCP RST packet to be sent back. This is mainly useful for blocking
+.I ident
+(113/tcp) probes which frequently occur when sending mail to broken mail
+hosts (which won't accept your mail otherwise).
+\fBtcp\-reset\fP
+can only be used with kernel versions 2.6.14 or later.
+.SS SECMARK
+This is used to set the security mark value associated with the
+packet for use by security subsystems such as SELinux. It is
+valid in the
+.B security
+table (for backwards compatibility with older kernels, it is also
+valid in the
+.B mangle
+table). The mark is 32 bits wide.
+.TP
+\fB\-\-selctx\fP \fIsecurity_context\fP
+.SS SET
+This modules adds and/or deletes entries from IP sets which can be defined
+by ipset(8).
+.TP
+\fB\-\-add\-set\fP \fIsetname\fP \fIflag\fP[\fB,\fP\fIflag\fP...]
+add the address(es)/port(s) of the packet to the sets
+.TP
+\fB\-\-del\-set\fP \fIsetname\fP \fIflag\fP[\fB,\fP\fIflag\fP...]
+delete the address(es)/port(s) of the packet from the sets
+.IP
+where flags are
+.BR "src"
+and/or
+.BR "dst"
+specifications and there can be no more than six of them.
+.TP
+\fB\-\-timeout\fP \fIvalue\fP
+when adding entry, the timeout value to use instead of the default
+one from the set definition
+.TP
+\fB\-\-exist\fP
+when adding entry if it already exists, reset the timeout value
+to the specified one or to the default from the set definition
+.PP
+Use of -j SET requires that ipset kernel support is provided, which, for
+standard kernels, is the case since Linux 2.6.39.
+.SS TCPMSS
+This target allows to alter the MSS value of TCP SYN packets, to control
+the maximum size for that connection (usually limiting it to your
+outgoing interface's MTU minus 40 for IPv4 or 60 for IPv6, respectively).
+Of course, it can only be used
+in conjunction with
+\fB\-p tcp\fP.
+.PP
+This target is used to overcome criminally braindead ISPs or servers
+which block "ICMP Fragmentation Needed" or "ICMPv6 Packet Too Big"
+packets. The symptoms of this
+problem are that everything works fine from your Linux
+firewall/router, but machines behind it can never exchange large
+packets:
+.IP 1. 4
+Web browsers connect, then hang with no data received.
+.IP 2. 4
+Small mail works fine, but large emails hang.
+.IP 3. 4
+ssh works fine, but scp hangs after initial handshaking.
+.PP
+Workaround: activate this option and add a rule to your firewall
+configuration like:
+.IP
+ iptables \-t mangle \-A FORWARD \-p tcp \-\-tcp\-flags SYN,RST SYN
+ \-j TCPMSS \-\-clamp\-mss\-to\-pmtu
+.TP
+\fB\-\-set\-mss\fP \fIvalue\fP
+Explicitly sets MSS option to specified value. If the MSS of the packet is
+already lower than \fIvalue\fP, it will \fBnot\fP be increased (from Linux
+2.6.25 onwards) to avoid more problems with hosts relying on a proper MSS.
+.TP
+\fB\-\-clamp\-mss\-to\-pmtu\fP
+Automatically clamp MSS value to (path_MTU \- 40 for IPv4; \-60 for IPv6).
+This may not function as desired where asymmetric routes with differing
+path MTU exist \(em the kernel uses the path MTU which it would use to send
+packets from itself to the source and destination IP addresses. Prior to
+Linux 2.6.25, only the path MTU to the destination IP address was
+considered by this option; subsequent kernels also consider the path MTU
+to the source IP address.
+.PP
+These options are mutually exclusive.
+.SS TCPOPTSTRIP
+This target will strip TCP options off a TCP packet. (It will actually replace
+them by NO-OPs.) As such, you will need to add the \fB\-p tcp\fP parameters.
+.TP
+\fB\-\-strip\-options\fP \fIoption\fP[\fB,\fP\fIoption\fP...]
+Strip the given option(s). The options may be specified by TCP option number or
+by symbolic name. The list of recognized options can be obtained by calling
+iptables with \fB\-j TCPOPTSTRIP \-h\fP.
+.SS TEE
+The \fBTEE\fP target will clone a packet and redirect this clone to another
+machine on the \fBlocal\fP network segment. In other words, the nexthop
+must be the target, or you will have to configure the nexthop to forward it
+further if so desired.
+.TP
+\fB\-\-gateway\fP \fIipaddr\fP
+Send the cloned packet to the host reachable at the given IP address.
+Use of 0.0.0.0 (for IPv4 packets) or :: (IPv6) is invalid.
+.PP
+To forward all incoming traffic on eth0 to an Network Layer logging box:
+.PP
+\-t mangle \-A PREROUTING \-i eth0 \-j TEE \-\-gateway 2001:db8::1
+.SS TOS
+This module sets the Type of Service field in the IPv4 header (including the
+"precedence" bits) or the Priority field in the IPv6 header. Note that TOS
+shares the same bits as DSCP and ECN. The TOS target is only valid in the
+\fBmangle\fP table.
+.TP
+\fB\-\-set\-tos\fP \fIvalue\fP[\fB/\fP\fImask\fP]
+Zeroes out the bits given by \fImask\fP (see NOTE below) and XORs \fIvalue\fP
+into the TOS/Priority field. If \fImask\fP is omitted, 0xFF is assumed.
+.TP
+\fB\-\-set\-tos\fP \fIsymbol\fP
+You can specify a symbolic name when using the TOS target for IPv4. It implies
+a mask of 0xFF (see NOTE below). The list of recognized TOS names can be
+obtained by calling iptables with \fB\-j TOS \-h\fP.
+.PP
+The following mnemonics are available:
+.TP
+\fB\-\-and\-tos\fP \fIbits\fP
+Binary AND the TOS value with \fIbits\fP. (Mnemonic for \fB\-\-set\-tos
+0/\fP\fIinvbits\fP, where \fIinvbits\fP is the binary negation of \fIbits\fP.
+See NOTE below.)
+.TP
+\fB\-\-or\-tos\fP \fIbits\fP
+Binary OR the TOS value with \fIbits\fP. (Mnemonic for \fB\-\-set\-tos\fP
+\fIbits\fP\fB/\fP\fIbits\fP. See NOTE below.)
+.TP
+\fB\-\-xor\-tos\fP \fIbits\fP
+Binary XOR the TOS value with \fIbits\fP. (Mnemonic for \fB\-\-set\-tos\fP
+\fIbits\fP\fB/0\fP. See NOTE below.)
+.PP
+NOTE: In Linux kernels up to and including 2.6.38, with the exception of
+longterm releases 2.6.32 (>=.42), 2.6.33 (>=.15), and 2.6.35 (>=.14), there is
+a bug whereby IPv6 TOS mangling does not behave as documented and differs from
+the IPv4 version. The TOS mask indicates the bits one wants to zero out, so it
+needs to be inverted before applying it to the original TOS field. However, the
+aformentioned kernels forgo the inversion which breaks --set-tos and its
+mnemonics.
+.SS TPROXY
+This target is only valid in the \fBmangle\fP table, in the \fBPREROUTING\fP
+chain and user-defined chains which are only called from this chain. It
+redirects the packet to a local socket without changing the packet header in
+any way. It can also change the mark value which can then be used in advanced
+routing rules.
+It takes three options:
+.TP
+\fB\-\-on\-port\fP \fIport\fP
+This specifies a destination port to use. It is a required option, 0 means the
+new destination port is the same as the original. This is only valid if the
+rule also specifies \fB\-p tcp\fP or \fB\-p udp\fP.
+.TP
+\fB\-\-on\-ip\fP \fIaddress\fP
+This specifies a destination address to use. By default the address is the IP
+address of the incoming interface. This is only valid if the rule also
+specifies \fB\-p tcp\fP or \fB\-p udp\fP.
+.TP
+\fB\-\-tproxy\-mark\fP \fIvalue\fP[\fB/\fP\fImask\fP]
+Marks packets with the given value/mask. The fwmark value set here can be used
+by advanced routing. (Required for transparent proxying to work: otherwise
+these packets will get forwarded, which is probably not what you want.)
+.SS TRACE
+This target marks packets so that the kernel will log every rule which match
+the packets as those traverse the tables, chains, rules.
+.PP
+A logging backend, such as ip(6)t_LOG or nfnetlink_log, must be loaded for this
+to be visible.
+The packets are logged with the string prefix:
+"TRACE: tablename:chainname:type:rulenum " where type can be "rule" for
+plain rule, "return" for implicit rule at the end of a user defined chain
+and "policy" for the policy of the built in chains.
+.br
+It can only be used in the
+.BR raw
+table.
+.SH DIAGNOSTICS
+Various error messages are printed to standard error. The exit code
+is 0 for correct functioning. Errors which appear to be caused by
+invalid or abused command line parameters cause an exit code of 2, and
+other errors cause an exit code of 1.
+.SH BUGS
+Bugs? What's this? ;-)
+Well... the counters are not reliable on sparc64.
+.SH COMPATIBILITY WITH IPCHAINS
+This \fBip6tables\fP
+is very similar to ipchains by Rusty Russell. The main difference is
+that the chains \fBINPUT\fP and \fBOUTPUT\fP
+are only traversed for packets coming into the local host and
+originating from the local host respectively. Hence every packet only
+passes through one of the three chains (except loopback traffic, which
+involves both INPUT and OUTPUT chains); previously a forwarded packet
+would pass through all three.
+.PP
+The other main difference is that \fB\-i\fP refers to the input interface;
+\fB\-o\fP refers to the output interface, and both are available for packets
+entering the \fBFORWARD\fP chain.
+There are several other changes in ip6tables.
+.SH SEE ALSO
+\fBip6tables\-save\fP(8),
+\fBip6tables\-restore\fP(8),
+\fBiptables\fP(8),
+\fBiptables\-save\fP(8),
+\fBiptables\-restore\fP(8),
+\fBlibipq\fP(3).
+.PP
+The packet-filtering-HOWTO details iptables usage for
+packet filtering,
+the netfilter-extensions-HOWTO details the extensions that are
+not in the standard distribution,
+and the netfilter-hacking-HOWTO details the netfilter internals.
+.br
+See
+.BR "http://www.netfilter.org/" .
+.SH AUTHORS
+Rusty Russell wrote iptables, in early consultation with Michael
+Neuling.
+.PP
+Marc Boucher made Rusty abandon ipnatctl by lobbying for a generic packet
+selection framework in iptables, then wrote the mangle table, the owner match,
+the mark stuff, and ran around doing cool stuff everywhere.
+.PP
+James Morris wrote the TOS target, and tos match.
+.PP
+Jozsef Kadlecsik wrote the REJECT target.
+.PP
+Harald Welte wrote the ULOG and NFQUEUE target, the new libiptc, as well as TTL match+target and libipulog.
+.PP
+The Netfilter Core Team is: Marc Boucher, Martin Josefsson, Yasuyuki Kozakai,
+Jozsef Kadlecsik, Patrick McHardy, James Morris, Pablo Neira Ayuso,
+Harald Welte and Rusty Russell.
+.PP
+ip6tables man page created by Andras Kis-Szabo, based on
+iptables man page written by Herve Eychenne <rv@wallfire.org>.
+.\" .. and did I mention that we are incredibly cool people?
+.\" .. sexy, too ..
+.\" .. witty, charming, powerful ..
+.\" .. and most of all, modest ..
+.SH VERSION
+.PP
+This manual page applies to ip6tables @PACKAGE_VERSION@.
--- /dev/null
+.\" Title: iptables-apply
+.\" Author: Martin F. Krafft
+.\" Date: Jun 04, 2006
+.\"
+.TH iptables\-apply 8 2006-06-04
+.\" disable hyphenation
+.nh
+.SH NAME
+iptables-apply \- a safer way to update iptables remotely
+.SH SYNOPSIS
+\fBiptables\-apply\fP [\-\fBhV\fP] [\fB-t\fP \fItimeout\fP] \fIruleset\-file\fP
+.SH "DESCRIPTION"
+.PP
+iptables\-apply will try to apply a new ruleset (as output by
+iptables\-save/read by iptables\-restore) to iptables, then prompt the
+user whether the changes are okay. If the new ruleset cut the existing
+connection, the user will not be able to answer affirmatively. In this
+case, the script rolls back to the previous ruleset after the timeout
+expired. The timeout can be set with \fB\-t\fP.
+.PP
+When called as ip6tables\-apply, the script will use
+ip6tables\-save/\-restore instead.
+.SH OPTIONS
+.TP
+\fB\-t\fP \fIseconds\fR, \fB\-\-timeout\fP \fIseconds\fR
+Sets the timeout after which the script will roll back to the previous
+ruleset.
+.TP
+\fB\-h\fP, \fB\-\-help\fP
+Display usage information.
+.TP
+\fB\-V\fP, \fB\-\-version\fP
+Display version information.
+.SH "SEE ALSO"
+.PP
+\fBiptables-restore\fP(8), \fBiptables-save\fP(8), \fBiptables\fR(8).
+.SH LEGALESE
+.PP
+iptables\-apply is copyright by Martin F. Krafft.
+.PP
+This manual page was written by Martin F. Krafft <madduck@madduck.net>
+.PP
+Permission is granted to copy, distribute and/or modify this document
+under the terms of the Artistic License 2.0.
.\"
.\"
.SH NAME
-iptables-restore \- Restore IP Tables
+iptables-restore \(em Restore IP Tables
.SH SYNOPSIS
-.BR "iptables-restore " "[-c] [-n]"
-.br
+\fBiptables\-restore\fP [\fB\-c\fP] [\fB\-n\fP] [\fB\-T\fP \fIname\fP]
.SH DESCRIPTION
.PP
.B iptables-restore
don't flush the previous contents of the table. If not specified,
.B iptables-restore
flushes (deletes) all previous contents of the respective IP Table.
+.TP
+\fB\-T\fP, \fB\-\-table\fP \fIname\fP
+Restore only the named table even if the input stream contains other ones.
.SH BUGS
None known as of iptables-1.2.1 release
.SH AUTHOR
Harald Welte <laforge@gnumonks.org>
.SH SEE ALSO
-.BR iptables-save "(8), " iptables "(8) "
+\fBiptables\-save\fP(8), \fBiptables\fP(8)
.PP
The iptables-HOWTO, which details more iptables usage, the NAT-HOWTO,
which details NAT, and the netfilter-hacking-HOWTO which details the
.\"
.\"
.SH NAME
-iptables-save \- Save IP Tables
+iptables-save \(em dump iptables rules to stdout
.SH SYNOPSIS
-.BR "iptables-save " "[-c] [-t table]"
-.br
+\fBiptables\-save\fP [\fB\-M\fP \fImodprobe\fP] [\fB\-c\fP]
+[\fB\-t\fP \fItable\fP]
.SH DESCRIPTION
.PP
.B iptables-save
is used to dump the contents of an IP Table in easily parseable format
to STDOUT. Use I/O-redirection provided by your shell to write to a file.
.TP
+\fB\-M\fP \fImodprobe_program\fP
+Specify the path to the modprobe program. By default, iptables-save will
+inspect /proc/sys/kernel/modprobe to determine the executable's path.
+.TP
\fB\-c\fR, \fB\-\-counters\fR
include the current values of all packet and byte counters in the output
.TP
-\fB\-t\fR, \fB\-\-table\fR \fBtablename\fR
+\fB\-t\fR, \fB\-\-table\fR \fItablename\fP
restrict output to only one table. If not specified, output includes all
available tables.
.SH BUGS
.SH AUTHOR
Harald Welte <laforge@gnumonks.org>
.SH SEE ALSO
-.BR iptables-restore "(8), " iptables "(8) "
+\fBiptables\-restore\fP(8), \fBiptables\fP(8)
.PP
The iptables-HOWTO, which details more iptables usage, the NAT-HOWTO,
which details NAT, and the netfilter-hacking-HOWTO which details the
-.TH IPTABLES 8 "Mar 09, 2002" "" ""
+.TH IPTABLES 8 "" "iptables 1.4.13" "iptables 1.4.13"
.\"
.\" Man page written by Herve Eychenne <rv@wallfire.org> (May 1999)
.\" It is based on ipchains page.
.\"
.\"
.SH NAME
-iptables \- administration tool for IPv4 packet filtering and NAT
+iptables \(em administration tool for IPv4 packet filtering and NAT
.SH SYNOPSIS
-.BR "iptables [-t table] -[AD] " "chain rule-specification [options]"
-.br
-.BR "iptables [-t table] -I " "chain [rulenum] rule-specification [options]"
-.br
-.BR "iptables [-t table] -R " "chain rulenum rule-specification [options]"
-.br
-.BR "iptables [-t table] -D " "chain rulenum [options]"
-.br
-.BR "iptables [-t table] -[LFZ] " "[chain] [options]"
-.br
-.BR "iptables [-t table] -N " "chain"
-.br
-.BR "iptables [-t table] -X " "[chain]"
-.br
-.BR "iptables [-t table] -P " "chain target [options]"
-.br
-.BR "iptables [-t table] -E " "old-chain-name new-chain-name"
+\fBiptables\fP [\fB\-t\fP \fItable\fP] {\fB\-A\fP|\fB\-C\fP|\fB\-D\fP}
+\fIchain\fP \fIrule-specification\fP
+.PP
+\fBiptables\fP [\fB\-t\fP \fItable\fP] \fB\-I\fP \fIchain\fP [\fIrulenum\fP] \fIrule-specification\fP
+.PP
+\fBiptables\fP [\fB\-t\fP \fItable\fP] \fB\-R\fP \fIchain rulenum rule-specification\fP
+.PP
+\fBiptables\fP [\fB\-t\fP \fItable\fP] \fB\-D\fP \fIchain rulenum\fP
+.PP
+\fBiptables\fP [\fB\-t\fP \fItable\fP] \fB\-S\fP [\fIchain\fP [\fIrulenum\fP]]
+.PP
+\fBiptables\fP [\fB\-t\fP \fItable\fP] {\fB\-F\fP|\fB\-L\fP|\fB\-Z\fP} [\fIchain\fP [\fIrulenum\fP]] [\fIoptions...\fP]
+.PP
+\fBiptables\fP [\fB\-t\fP \fItable\fP] \fB\-N\fP \fIchain\fP
+.PP
+\fBiptables\fP [\fB\-t\fP \fItable\fP] \fB\-X\fP [\fIchain\fP]
+.PP
+\fBiptables\fP [\fB\-t\fP \fItable\fP] \fB\-P\fP \fIchain target\fP
+.PP
+\fBiptables\fP [\fB\-t\fP \fItable\fP] \fB\-E\fP \fIold-chain-name new-chain-name\fP
+.PP
+rule-specification = [\fImatches...\fP] [\fItarget\fP]
+.PP
+match = \fB\-m\fP \fImatchname\fP [\fIper-match-options\fP]
+.PP
+target = \fB\-j\fP \fItargetname\fP [\fIper\-target\-options\fP]
.SH DESCRIPTION
-.B Iptables
-is used to set up, maintain, and inspect the tables of IP packet
+\fBIptables\fP is used to set up, maintain, and inspect the
+tables of IPv4 packet
filter rules in the Linux kernel. Several different tables
may be defined. Each table contains a number of built-in
chains and may also contain user-defined chains.
-
+.PP
Each chain is a list of rules which can match a set of packets. Each
rule specifies what to do with a packet that matches. This is called
a `target', which may be a jump to a user-defined chain in the same
table.
-
.SH TARGETS
-A firewall rule specifies criteria for a packet, and a target. If the
+A firewall rule specifies criteria for a packet and a target. If the
packet does not match, the next rule in the chain is the examined; if
it does match, then the next rule is specified by the value of the
target, which can be the name of a user-defined chain or one of the
-special values
-.IR ACCEPT ,
-.IR DROP ,
-.IR QUEUE ,
-or
-.IR RETURN .
-.PP
-.I ACCEPT
-means to let the packet through.
-.I DROP
-means to drop the packet on the floor.
-.I QUEUE
-means to pass the packet to userspace (if supported by the kernel).
-.I RETURN
-means stop traversing this chain and resume at the next rule in the
+special values \fBACCEPT\fP, \fBDROP\fP, \fBQUEUE\fP or \fBRETURN\fP.
+.PP
+\fBACCEPT\fP means to let the packet through.
+\fBDROP\fP means to drop the packet on the floor.
+\fBQUEUE\fP means to pass the packet to userspace.
+(How the packet can be received
+by a userspace process differs by the particular queue handler. 2.4.x
+and 2.6.x kernels up to 2.6.13 include the \fBip_queue\fP
+queue handler. Kernels 2.6.14 and later additionally include the
+\fBnfnetlink_queue\fP queue handler. Packets with a target of QUEUE will be
+sent to queue number '0' in this case. Please also see the \fBNFQUEUE\fP
+target as described later in this man page.)
+\fBRETURN\fP means stop traversing this chain and resume at the next
+rule in the
previous (calling) chain. If the end of a built-in chain is reached
-or a rule in a built-in chain with target
-.I RETURN
+or a rule in a built-in chain with target \fBRETURN\fP
is matched, the target specified by the chain policy determines the
fate of the packet.
.SH TABLES
at any time depends on the kernel configuration options and which
modules are present).
.TP
-.BI "-t, --table " "table"
+\fB\-t\fP, \fB\-\-table\fP \fItable\fP
This option specifies the packet matching table which the command
should operate on. If the kernel is configured with automatic module
loading, an attempt will be made to load the appropriate module for
The tables are as follows:
.RS
.TP .4i
-.BR "filter" :
-This is the default table (if no -t option is passed). It contains
-the built-in chains
-.B INPUT
-(for packets coming into the box itself),
-.B FORWARD
-(for packets being routed through the box), and
-.B OUTPUT
-(for locally-generated packets).
+\fBfilter\fP:
+This is the default table (if no \-t option is passed). It contains
+the built-in chains \fBINPUT\fP (for packets destined to local sockets),
+\fBFORWARD\fP (for packets being routed through the box), and
+\fBOUTPUT\fP (for locally-generated packets).
.TP
-.BR "nat" :
+\fBnat\fP:
This table is consulted when a packet that creates a new
-connection is encountered. It consists of three built-ins:
-.B PREROUTING
-(for altering packets as soon as they come in),
-.B OUTPUT
-(for altering locally-generated packets before routing), and
-.B POSTROUTING
+connection is encountered. It consists of three built-ins: \fBPREROUTING\fP
+(for altering packets as soon as they come in), \fBOUTPUT\fP
+(for altering locally-generated packets before routing), and \fBPOSTROUTING\fP
(for altering packets as they are about to go out).
.TP
-.BR "mangle" :
+\fBmangle\fP:
This table is used for specialized packet alteration. Until kernel
-2.4.17 it had two built-in chains:
-.B PREROUTING
-(for altering incoming packets before routing) and
-.B OUTPUT
+2.4.17 it had two built-in chains: \fBPREROUTING\fP
+(for altering incoming packets before routing) and \fBOUTPUT\fP
(for altering locally-generated packets before routing).
Since kernel 2.4.18, three other built-in chains are also supported:
-.B INPUT
-(for packets coming into the box itself),
-.B FORWARD
-(for altering packets being routed through the box), and
-.B POSTROUTING
+\fBINPUT\fP (for packets coming into the box itself), \fBFORWARD\fP
+(for altering packets being routed through the box), and \fBPOSTROUTING\fP
(for altering packets as they are about to go out).
+.TP
+\fBraw\fP:
+This table is used mainly for configuring exemptions from connection
+tracking in combination with the NOTRACK target. It registers at the netfilter
+hooks with higher priority and is thus called before ip_conntrack, or any other
+IP tables. It provides the following built-in chains: \fBPREROUTING\fP
+(for packets arriving via any network interface) \fBOUTPUT\fP
+(for packets generated by local processes)
+.TP
+\fBsecurity\fP:
+This table is used for Mandatory Access Control (MAC) networking rules, such
+as those enabled by the \fBSECMARK\fP and \fBCONNSECMARK\fP targets.
+Mandatory Access Control is implemented by Linux Security Modules such as
+SELinux. The security table is called after the filter table, allowing any
+Discretionary Access Control (DAC) rules in the filter table to take effect
+before MAC rules. This table provides the following built-in chains:
+\fBINPUT\fP (for packets coming into the box itself),
+\fBOUTPUT\fP (for altering locally-generated packets before routing), and
+\fBFORWARD\fP (for altering packets being routed through the box).
.RE
.SH OPTIONS
The options that are recognized by
-.B iptables
-can be divided into several different groups.
+\fBiptables\fP can be divided into several different groups.
.SS COMMANDS
-These options specify the specific action to perform. Only one of them
-can be specified on the command line unless otherwise specified
-below. For all the long versions of the command and option names, you
+These options specify the desired action to perform. Only one of them
+can be specified on the command line unless otherwise stated
+below. For long versions of the command and option names, you
need to use only enough letters to ensure that
-.B iptables
-can differentiate it from all other options.
+\fBiptables\fP can differentiate it from all other options.
.TP
-.BI "-A, --append " "chain rule-specification"
+\fB\-A\fP, \fB\-\-append\fP \fIchain rule-specification\fP
Append one or more rules to the end of the selected chain.
When the source and/or destination names resolve to more than one
address, a rule will be added for each possible address combination.
.TP
-.BI "-D, --delete " "chain rule-specification"
+\fB\-C\fP, \fB\-\-check\fP \fIchain rule-specification\fP
+Check whether a rule matching the specification does exist in the
+selected chain. This command uses the same logic as \fB\-D\fP to
+find a matching entry, but does not alter the existing iptables
+configuration and uses its exit code to indicate success or failure.
+.TP
+\fB\-D\fP, \fB\-\-delete\fP \fIchain rule-specification\fP
.ns
.TP
-.BI "-D, --delete " "chain rulenum"
+\fB\-D\fP, \fB\-\-delete\fP \fIchain rulenum\fP
Delete one or more rules from the selected chain. There are two
versions of this command: the rule can be specified as a number in the
chain (starting at 1 for the first rule) or a rule to match.
.TP
-.BR "-I, --insert " "\fIchain\fP [\fIrulenum\fP] \fIrule-specification\fP"
+\fB\-I\fP, \fB\-\-insert\fP \fIchain\fP [\fIrulenum\fP] \fIrule-specification\fP
Insert one or more rules in the selected chain as the given rule
number. So, if the rule number is 1, the rule or rules are inserted
at the head of the chain. This is also the default if no rule number
is specified.
.TP
-.BI "-R, --replace " "chain rulenum rule-specification"
+\fB\-R\fP, \fB\-\-replace\fP \fIchain rulenum rule-specification\fP
Replace a rule in the selected chain. If the source and/or
destination names resolve to multiple addresses, the command will
fail. Rules are numbered starting at 1.
.TP
-.BR "-L, --list " "[\fIchain\fP]"
+\fB\-L\fP, \fB\-\-list\fP [\fIchain\fP]
List all rules in the selected chain. If no chain is selected, all
-chains are listed. As every other iptables command, it applies to the
+chains are listed. Like every other iptables command, it applies to the
specified table (filter is the default), so NAT rules get listed by
.nf
- iptables -t nat -n -L
+ iptables \-t nat \-n \-L
.fi
-Please note that it is often used with the
-.B -n
+Please note that it is often used with the \fB\-n\fP
option, in order to avoid long reverse DNS lookups.
-It is legal to specify the
-.B -Z
+It is legal to specify the \fB\-Z\fP
(zero) option as well, in which case the chain(s) will be atomically
listed and zeroed. The exact output is affected by the other
arguments given. The exact rules are suppressed until you use
.nf
- iptables -L -v
+ iptables \-L \-v
.fi
.TP
-.BR "-F, --flush " "[\fIchain\fP]"
+\fB\-S\fP, \fB\-\-list\-rules\fP [\fIchain\fP]
+Print all rules in the selected chain. If no chain is selected, all
+chains are printed like iptables-save. Like every other iptables command,
+it applies to the specified table (filter is the default).
+.TP
+\fB\-F\fP, \fB\-\-flush\fP [\fIchain\fP]
Flush the selected chain (all the chains in the table if none is given).
This is equivalent to deleting all the rules one by one.
.TP
-.BR "-Z, --zero " "[\fIchain\fP]"
-Zero the packet and byte counters in all chains. It is legal to
+\fB\-Z\fP, \fB\-\-zero\fP [\fIchain\fP [\fIrulenum\fP]]
+Zero the packet and byte counters in all chains, or only the given chain,
+or only the given rule in a chain. It is legal to
specify the
-.B "-L, --list"
+\fB\-L\fP, \fB\-\-list\fP
(list) option as well, to see the counters immediately before they are
cleared. (See above.)
.TP
-.BI "-N, --new-chain " "chain"
+\fB\-N\fP, \fB\-\-new\-chain\fP \fIchain\fP
Create a new user-defined chain by the given name. There must be no
target of that name already.
.TP
-.BR "-X, --delete-chain " "[\fIchain\fP]"
+\fB\-X\fP, \fB\-\-delete\-chain\fP [\fIchain\fP]
Delete the optional user-defined chain specified. There must be no references
-to the chain. If there are, you must delete or replace the referring
-rules before the chain can be deleted. If no argument is given, it
-will attempt to delete every non-builtin chain in the table.
+to the chain. If there are, you must delete or replace the referring rules
+before the chain can be deleted. The chain must be empty, i.e. not contain
+any rules. If no argument is given, it will attempt to delete every
+non-builtin chain in the table.
.TP
-.BI "-P, --policy " "chain target"
-Set the policy for the chain to the given target. See the section
-.B TARGETS
+\fB\-P\fP, \fB\-\-policy\fP \fIchain target\fP
+Set the policy for the chain to the given target. See the section \fBTARGETS\fP
for the legal targets. Only built-in (non-user-defined) chains can have
policies, and neither built-in nor user-defined chains can be policy
targets.
.TP
-.BI "-E, --rename-chain " "old-chain new-chain"
+\fB\-E\fP, \fB\-\-rename\-chain\fP \fIold\-chain new\-chain\fP
Rename the user specified chain to the user supplied name. This is
cosmetic, and has no effect on the structure of the table.
.TP
-.B -h
+\fB\-h\fP
Help.
Give a (currently very brief) description of the command syntax.
.SS PARAMETERS
The following parameters make up a rule specification (as used in the
add, delete, insert, replace and append commands).
.TP
-.BR "-p, --protocol " "[!] \fIprotocol\fP"
+[\fB!\fP] \fB\-p\fP, \fB\-\-protocol\fP \fIprotocol\fP
The protocol of the rule or of the packet to check.
-The specified protocol can be one of
-.IR tcp ,
-.IR udp ,
-.IR icmp ,
-or
-.IR all ,
+The specified protocol can be one of \fBtcp\fP, \fBudp\fP, \fBudplite\fP,
+\fBicmp\fP, \fBesp\fP, \fBah\fP, \fBsctp\fP or the special keyword "\fBall\fP",
or it can be a numeric value, representing one of these protocols or a
different one. A protocol name from /etc/protocols is also allowed.
A "!" argument before the protocol inverts the
-test. The number zero is equivalent to
-.IR all .
-Protocol
-.I all
+test. The number zero is equivalent to \fBall\fP. "\fBall\fP"
will match with all protocols and is taken as default when this
option is omitted.
.TP
-.BR "-s, --source " "[!] \fIaddress\fP[/\fImask\fP]"
-Source specification.
-.I Address
-can be either a network name, a hostname (please note that specifying
-any name to be resolved with a remote query such as DNS is a really bad idea),
-a network IP address (with /mask), or a plain IP address.
-The
-.I mask
+[\fB!\fP] \fB\-s\fP, \fB\-\-source\fP \fIaddress\fP[\fB/\fP\fImask\fP][\fB,\fP\fI...\fP]
+Source specification. \fIAddress\fP
+can be either a network name, a hostname, a network IP address (with
+\fB/\fP\fImask\fP), or a plain IP address. Hostnames will
+be resolved once only, before the rule is submitted to the kernel.
+Please note that specifying any name to be resolved with a remote query such as
+DNS is a really bad idea.
+The \fImask\fP
can be either a network mask or a plain number,
specifying the number of 1's at the left side of the network mask.
-Thus, a mask of
-.I 24
-is equivalent to
-.IR 255.255.255.0 .
+Thus, a mask of \fI24\fP is equivalent to \fI255.255.255.0\fP.
A "!" argument before the address specification inverts the sense of
-the address. The flag
-.B --src
-is an alias for this option.
+the address. The flag \fB\-\-src\fP is an alias for this option.
+Multiple addresses can be specified, but this will \fBexpand to multiple
+rules\fP (when adding with \-A), or will cause multiple rules to be
+deleted (with \-D).
.TP
-.BR "-d, --destination " "[!] \fIaddress\fP[/\fImask\fP]"
+[\fB!\fP] \fB\-d\fP, \fB\-\-destination\fP \fIaddress\fP[\fB/\fP\fImask\fP][\fB,\fP\fI...\fP]
Destination specification.
-See the description of the
-.B -s
+See the description of the \fB\-s\fP
(source) flag for a detailed description of the syntax. The flag
-.B --dst
-is an alias for this option.
+\fB\-\-dst\fP is an alias for this option.
.TP
-.BI "-j, --jump " "target"
+\fB\-j\fP, \fB\-\-jump\fP \fItarget\fP
This specifies the target of the rule; i.e., what to do if the packet
matches it. The target can be a user-defined chain (other than the
one this rule is in), one of the special builtin targets which decide
-the fate of the packet immediately, or an extension (see
-.B EXTENSIONS
+the fate of the packet immediately, or an extension (see \fBEXTENSIONS\fP
below). If this
-option is omitted in a rule, then matching the rule will have no
+option is omitted in a rule (and \fB\-g\fP
+is not used), then matching the rule will have no
effect on the packet's fate, but the counters on the rule will be
incremented.
.TP
-.BR "-i, --in-interface " "[!] \fIname\fP"
-Name of an interface via which a packet is going to be received (only for
-packets entering the
-.BR INPUT ,
-.B FORWARD
-and
-.B PREROUTING
+\fB\-g\fP, \fB\-\-goto\fP \fIchain\fP
+This specifies that the processing should continue in a user
+specified chain. Unlike the \-\-jump option return will not continue
+processing in this chain but instead in the chain that called us via
+\-\-jump.
+.TP
+[\fB!\fP] \fB\-i\fP, \fB\-\-in\-interface\fP \fIname\fP
+Name of an interface via which a packet was received (only for
+packets entering the \fBINPUT\fP, \fBFORWARD\fP and \fBPREROUTING\fP
chains). When the "!" argument is used before the interface name, the
sense is inverted. If the interface name ends in a "+", then any
interface which begins with this name will match. If this option is
omitted, any interface name will match.
.TP
-.BR "-o, --out-interface " "[!] \fIname\fP"
+[\fB!\fP] \fB\-o\fP, \fB\-\-out\-interface\fP \fIname\fP
Name of an interface via which a packet is going to be sent (for packets
-entering the
-.BR FORWARD ,
-.B OUTPUT
-and
-.B POSTROUTING
+entering the \fBFORWARD\fP, \fBOUTPUT\fP and \fBPOSTROUTING\fP
chains). When the "!" argument is used before the interface name, the
sense is inverted. If the interface name ends in a "+", then any
interface which begins with this name will match. If this option is
omitted, any interface name will match.
.TP
-.B "[!] " "-f, --fragment"
+[\fB!\fP] \fB\-f\fP, \fB\-\-fragment\fP
This means that the rule only refers to second and further fragments
of fragmented packets. Since there is no way to tell the source or
destination ports of such a packet (or ICMP type), such a packet will
not match any rules which specify them. When the "!" argument
-precedes the "-f" flag, the rule will only match head fragments, or
+precedes the "\-f" flag, the rule will only match head fragments, or
unfragmented packets.
.TP
-.BI "-c, --set-counters " "PKTS BYTES"
+\fB\-c\fP, \fB\-\-set\-counters\fP \fIpackets bytes\fP
This enables the administrator to initialize the packet and byte
-counters of a rule (during
-.B INSERT,
-.B APPEND,
-.B REPLACE
+counters of a rule (during \fBINSERT\fP, \fBAPPEND\fP, \fBREPLACE\fP
operations).
.SS "OTHER OPTIONS"
The following additional options can be specified:
.TP
-.B "-v, --verbose"
+\fB\-v\fP, \fB\-\-verbose\fP
Verbose output. This option makes the list command show the interface
name, the rule options (if any), and the TOS masks. The packet and
byte counters are also listed, with the suffix 'K', 'M' or 'G' for
1000, 1,000,000 and 1,000,000,000 multipliers respectively (but see
-the
-.B -x
-flag to change this).
+the \fB\-x\fP flag to change this).
For appending, insertion, deletion and replacement, this causes
-detailed information on the rule or rules to be printed.
+detailed information on the rule or rules to be printed. \fB\-v\fP may be
+specified multiple times to possibly emit more detailed debug statements.
.TP
-.B "-n, --numeric"
+\fB\-n\fP, \fB\-\-numeric\fP
Numeric output.
IP addresses and port numbers will be printed in numeric format.
By default, the program will try to display them as host names,
network names, or services (whenever applicable).
.TP
-.B "-x, --exact"
+\fB\-x\fP, \fB\-\-exact\fP
Expand numbers.
Display the exact value of the packet and byte counters,
instead of only the rounded number in K's (multiples of 1000)
M's (multiples of 1000K) or G's (multiples of 1000M). This option is
-only relevant for the
-.B -L
-command.
+only relevant for the \fB\-L\fP command.
.TP
-.B "--line-numbers"
+\fB\-\-line\-numbers\fP
When listing rules, add line numbers to the beginning of each rule,
corresponding to that rule's position in the chain.
.TP
-.B "--modprobe=command"
-When adding or inserting rules into a chain, use
-.B command
+\fB\-\-modprobe=\fP\fIcommand\fP
+When adding or inserting rules into a chain, use \fIcommand\fP
to load any necessary modules (targets, match extensions, etc).
.SH MATCH EXTENSIONS
-iptables can use extended packet matching modules. These are loaded
-in two ways: implicitly, when
-.B -p
-or
-.B --protocol
-is specified, or with the
-.B -m
-or
-.B --match
+.PP
+iptables can use extended packet matching modules
+with the \fB\-m\fP or \fB\-\-match\fP
options, followed by the matching module name; after these, various
extra command line options become available, depending on the specific
module. You can specify multiple extended match modules in one line,
-and you can use the
-.B -h
-or
-.B --help
+and you can use the \fB\-h\fP or \fB\-\-help\fP
options after the module has been specified to receive help specific
to that module.
-
-The following are included in the base package, and most of these can
-be preceded by a
-.B !
-to invert the sense of the match.
+.PP
+If the \fB\-p\fP or \fB\-\-protocol\fP was specified and if and only if an
+unknown option is encountered, iptables will try load a match module of the
+same name as the protocol, to try making the option available.
+.\" @MATCH@
+.SS addrtype
+This module matches packets based on their
+.B address type.
+Address types are used within the kernel networking stack and categorize
+addresses into various groups. The exact definition of that group depends on the specific layer three protocol.
+.PP
+The following address types are possible:
+.TP
+.BI "UNSPEC"
+an unspecified address (i.e. 0.0.0.0)
+.TP
+.BI "UNICAST"
+an unicast address
+.TP
+.BI "LOCAL"
+a local address
+.TP
+.BI "BROADCAST"
+a broadcast address
+.TP
+.BI "ANYCAST"
+an anycast packet
+.TP
+.BI "MULTICAST"
+a multicast address
+.TP
+.BI "BLACKHOLE"
+a blackhole address
+.TP
+.BI "UNREACHABLE"
+an unreachable address
+.TP
+.BI "PROHIBIT"
+a prohibited address
+.TP
+.BI "THROW"
+FIXME
+.TP
+.BI "NAT"
+FIXME
+.TP
+.BI "XRESOLVE"
+.TP
+[\fB!\fP] \fB\-\-src\-type\fP \fItype\fP
+Matches if the source address is of given type
+.TP
+[\fB!\fP] \fB\-\-dst\-type\fP \fItype\fP
+Matches if the destination address is of given type
+.TP
+.BI "\-\-limit\-iface\-in"
+The address type checking can be limited to the interface the packet is coming
+in. This option is only valid in the
+.BR PREROUTING ,
+.B INPUT
+and
+.B FORWARD
+chains. It cannot be specified with the
+\fB\-\-limit\-iface\-out\fP
+option.
+.TP
+\fB\-\-limit\-iface\-out\fP
+The address type checking can be limited to the interface the packet is going
+out. This option is only valid in the
+.BR POSTROUTING ,
+.B OUTPUT
+and
+.B FORWARD
+chains. It cannot be specified with the
+\fB\-\-limit\-iface\-in\fP
+option.
.SS ah
-This module matches the SPIs in AH header of IPSec packets.
+This module matches the SPIs in Authentication header of IPsec packets.
+.TP
+[\fB!\fP] \fB\-\-ahspi\fP \fIspi\fP[\fB:\fP\fIspi\fP]
+.SS cluster
+Allows you to deploy gateway and back-end load-sharing clusters without the
+need of load-balancers.
+.PP
+This match requires that all the nodes see the same packets. Thus, the cluster
+match decides if this node has to handle a packet given the following options:
.TP
-.BR "--ahspi " "[!] \fIspi\fP[:\fIspi\fP]"
+\fB\-\-cluster\-total\-nodes\fP \fInum\fP
+Set number of total nodes in cluster.
+.TP
+[\fB!\fP] \fB\-\-cluster\-local\-node\fP \fInum\fP
+Set the local node number ID.
+.TP
+[\fB!\fP] \fB\-\-cluster\-local\-nodemask\fP \fImask\fP
+Set the local node number ID mask. You can use this option instead
+of \fB\-\-cluster\-local\-node\fP.
+.TP
+\fB\-\-cluster\-hash\-seed\fP \fIvalue\fP
+Set seed value of the Jenkins hash.
+.PP
+Example:
+.IP
+iptables \-A PREROUTING \-t mangle \-i eth1 \-m cluster
+\-\-cluster\-total\-nodes 2 \-\-cluster\-local\-node 1
+\-\-cluster\-hash\-seed 0xdeadbeef
+\-j MARK \-\-set-mark 0xffff
+.IP
+iptables \-A PREROUTING \-t mangle \-i eth2 \-m cluster
+\-\-cluster\-total\-nodes 2 \-\-cluster\-local\-node 1
+\-\-cluster\-hash\-seed 0xdeadbeef
+\-j MARK -\-set\-mark 0xffff
+.IP
+iptables \-A PREROUTING \-t mangle \-i eth1
+\-m mark ! \-\-mark 0xffff \-j DROP
+.IP
+iptables \-A PREROUTING \-t mangle \-i eth2
+\-m mark ! \-\-mark 0xffff \-j DROP
+.PP
+And the following commands to make all nodes see the same packets:
+.IP
+ip maddr add 01:00:5e:00:01:01 dev eth1
+.IP
+ip maddr add 01:00:5e:00:01:02 dev eth2
+.IP
+arptables \-A OUTPUT \-o eth1 \-\-h\-length 6
+\-j mangle \-\-mangle-mac-s 01:00:5e:00:01:01
+.IP
+arptables \-A INPUT \-i eth1 \-\-h-length 6
+\-\-destination-mac 01:00:5e:00:01:01
+\-j mangle \-\-mangle\-mac\-d 00:zz:yy:xx:5a:27
+.IP
+arptables \-A OUTPUT \-o eth2 \-\-h\-length 6
+\-j mangle \-\-mangle\-mac\-s 01:00:5e:00:01:02
+.IP
+arptables \-A INPUT \-i eth2 \-\-h\-length 6
+\-\-destination\-mac 01:00:5e:00:01:02
+\-j mangle \-\-mangle\-mac\-d 00:zz:yy:xx:5a:27
+.PP
+In the case of TCP connections, pickup facility has to be disabled
+to avoid marking TCP ACK packets coming in the reply direction as
+valid.
+.IP
+echo 0 > /proc/sys/net/netfilter/nf_conntrack_tcp_loose
+.SS comment
+Allows you to add comments (up to 256 characters) to any rule.
+.TP
+\fB\-\-comment\fP \fIcomment\fP
+.TP
+Example:
+iptables \-A INPUT \-i eth1 \-m comment \-\-comment "my local LAN"
+.SS connbytes
+Match by how many bytes or packets a connection (or one of the two
+flows constituting the connection) has transferred so far, or by
+average bytes per packet.
+.PP
+The counters are 64-bit and are thus not expected to overflow ;)
+.PP
+The primary use is to detect long-lived downloads and mark them to be
+scheduled using a lower priority band in traffic control.
+.PP
+The transferred bytes per connection can also be viewed through
+`conntrack \-L` and accessed via ctnetlink.
+.PP
+NOTE that for connections which have no accounting information, the match will
+always return false. The "net.netfilter.nf_conntrack_acct" sysctl flag controls
+whether \fBnew\fP connections will be byte/packet counted. Existing connection
+flows will not be gaining/losing a/the accounting structure when be sysctl flag
+is flipped.
+.TP
+[\fB!\fP] \fB\-\-connbytes\fP \fIfrom\fP[\fB:\fP\fIto\fP]
+match packets from a connection whose packets/bytes/average packet
+size is more than FROM and less than TO bytes/packets. if TO is
+omitted only FROM check is done. "!" is used to match packets not
+falling in the range.
+.TP
+\fB\-\-connbytes\-dir\fP {\fBoriginal\fP|\fBreply\fP|\fBboth\fP}
+which packets to consider
+.TP
+\fB\-\-connbytes\-mode\fP {\fBpackets\fP|\fBbytes\fP|\fBavgpkt\fP}
+whether to check the amount of packets, number of bytes transferred or
+the average size (in bytes) of all packets received so far. Note that
+when "both" is used together with "avgpkt", and data is going (mainly)
+only in one direction (for example HTTP), the average packet size will
+be about half of the actual data packets.
+.TP
+Example:
+iptables .. \-m connbytes \-\-connbytes 10000:100000 \-\-connbytes\-dir both \-\-connbytes\-mode bytes ...
+.SS connlimit
+Allows you to restrict the number of parallel connections to a server per
+client IP address (or client address block).
+.TP
+\fB\-\-connlimit\-upto\fP \fIn\fP
+Match if the number of existing connections is below or equal \fIn\fP.
+.TP
+\fB\-\-connlimit\-above\fP \fIn\fP
+Match if the number of existing connections is above \fIn\fP.
+.TP
+\fB\-\-connlimit\-mask\fP \fIprefix_length\fP
+Group hosts using the prefix length. For IPv4, this must be a number between
+(including) 0 and 32. For IPv6, between 0 and 128. If not specified, the
+maximum prefix length for the applicable protocol is used.
+.TP
+\fB\-\-connlimit\-saddr\fP
+Apply the limit onto the source group. This is the default if
+\-\-connlimit\-daddr is not specified.
+.TP
+\fB\-\-connlimit\-daddr\fP
+Apply the limit onto the destination group.
+.PP
+Examples:
+.TP
+# allow 2 telnet connections per client host
+iptables \-A INPUT \-p tcp \-\-syn \-\-dport 23 \-m connlimit \-\-connlimit\-above 2 \-j REJECT
+.TP
+# you can also match the other way around:
+iptables \-A INPUT \-p tcp \-\-syn \-\-dport 23 \-m connlimit \-\-connlimit\-upto 2 \-j ACCEPT
+.TP
+# limit the number of parallel HTTP requests to 16 per class C sized \
+source network (24 bit netmask)
+iptables \-p tcp \-\-syn \-\-dport 80 \-m connlimit \-\-connlimit\-above 16
+\-\-connlimit\-mask 24 \-j REJECT
+.TP
+# limit the number of parallel HTTP requests to 16 for the link local network
+(ipv6)
+ip6tables \-p tcp \-\-syn \-\-dport 80 \-s fe80::/64 \-m connlimit \-\-connlimit\-above
+16 \-\-connlimit\-mask 64 \-j REJECT
+.TP
+# Limit the number of connections to a particular host:
+ip6tables \-p tcp \-\-syn \-\-dport 49152:65535 \-d 2001:db8::1 \-m connlimit
+\-\-connlimit-above 100 \-j REJECT
+.SS connmark
+This module matches the netfilter mark field associated with a connection
+(which can be set using the \fBCONNMARK\fP target below).
+.TP
+[\fB!\fP] \fB\-\-mark\fP \fIvalue\fP[\fB/\fP\fImask\fP]
+Matches packets in connections with the given mark value (if a mask is
+specified, this is logically ANDed with the mark before the comparison).
.SS conntrack
-This module, when combined with connection tracking, allows access to
-more connection tracking information than the "state" match.
-(this module is present only if iptables was compiled under a kernel
-supporting this feature)
+This module, when combined with connection tracking, allows access to the
+connection tracking state for this packet/connection.
.TP
-.BI "--ctstate " "state"
-Where state is a comma separated list of the connection states to
-match. Possible states are
-.B INVALID
-meaning that the packet is associated with no known connection,
-.B ESTABLISHED
-meaning that the packet is associated with a connection which has seen
-packets in both directions,
-.B NEW
-meaning that the packet has started a new connection, or otherwise
-associated with a connection which has not seen packets in both
-directions, and
-.B RELATED
-meaning that the packet is starting a new connection, but is
-associated with an existing connection, such as an FTP data transfer,
-or an ICMP error.
-.B SNAT
-A virtual state, matching if the original source address differs from
-the reply destination.
-.B DNAT
-A virtual state, matching if the original destination differs from the
-reply source.
+[\fB!\fP] \fB\-\-ctstate\fP \fIstatelist\fP
+\fIstatelist\fP is a comma separated list of the connection states to match.
+Possible states are listed below.
.TP
-.BI "--ctproto " "proto"
-Protocol to match (by number or name)
+[\fB!\fP] \fB\-\-ctproto\fP \fIl4proto\fP
+Layer-4 protocol to match (by number or name)
.TP
-.BI "--ctorigsrc " "[!] \fIaddress\fP[/\fImask\fP]"
-Match against original source address
+[\fB!\fP] \fB\-\-ctorigsrc\fP \fIaddress\fP[\fB/\fP\fImask\fP]
.TP
-.BI "--ctorigdst " "[!] \fIaddress\fP[/\fImask\fP]"
-Match against original destination address
+[\fB!\fP] \fB\-\-ctorigdst\fP \fIaddress\fP[\fB/\fP\fImask\fP]
.TP
-.BI "--ctreplsrc " "[!] \fIaddress\fP[/\fImask\fP]"
-Match against reply source address
+[\fB!\fP] \fB\-\-ctreplsrc\fP \fIaddress\fP[\fB/\fP\fImask\fP]
.TP
-.BI "--ctrepldst " "[!] \fIaddress\fB[/\fImask\fP]"
-Match against reply destination address
+[\fB!\fP] \fB\-\-ctrepldst\fP \fIaddress\fP[\fB/\fP\fImask\fP]
+Match against original/reply source/destination address
.TP
-.BI "--ctstatus " "[\fINONE|EXPECTED|SEEN_REPLY|ASSURED\fP][,...]"
-Match against internal conntrack states
+[\fB!\fP] \fB\-\-ctorigsrcport\fP \fIport\fP[\fB:\fP\fIport\fP]
.TP
-.BI "--ctexpire " "\fItime\fP[\fI:time\fP]"
-Match remaining lifetime in seconds against given value
-or range of values (inclusive)
+[\fB!\fP] \fB\-\-ctorigdstport\fP \fIport\fP[\fB:\fP\fIport\fP]
+.TP
+[\fB!\fP] \fB\-\-ctreplsrcport\fP \fIport\fP[\fB:\fP\fIport\fP]
+.TP
+[\fB!\fP] \fB\-\-ctrepldstport\fP \fIport\fP[\fB:\fP\fIport\fP]
+Match against original/reply source/destination port (TCP/UDP/etc.) or GRE key.
+Matching against port ranges is only supported in kernel versions above 2.6.38.
+.TP
+[\fB!\fP] \fB\-\-ctstatus\fP \fIstatelist\fP
+\fIstatuslist\fP is a comma separated list of the connection statuses to match.
+Possible statuses are listed below.
+.TP
+[\fB!\fP] \fB\-\-ctexpire\fP \fItime\fP[\fB:\fP\fItime\fP]
+Match remaining lifetime in seconds against given value or range of values
+(inclusive)
+.TP
+\fB\-\-ctdir\fP {\fBORIGINAL\fP|\fBREPLY\fP}
+Match packets that are flowing in the specified direction. If this flag is not
+specified at all, matches packets in both directions.
+.PP
+States for \fB\-\-ctstate\fP:
+.TP
+\fBINVALID\fP
+meaning that the packet is associated with no known connection
+.TP
+\fBNEW\fP
+meaning that the packet has started a new connection, or otherwise associated
+with a connection which has not seen packets in both directions, and
+.TP
+\fBESTABLISHED\fP
+meaning that the packet is associated with a connection which has seen packets
+in both directions,
+.TP
+\fBRELATED\fP
+meaning that the packet is starting a new connection, but is associated with an
+existing connection, such as an FTP data transfer, or an ICMP error.
+.TP
+\fBUNTRACKED\fP
+meaning that the packet is not tracked at all, which happens if you use
+the NOTRACK target in raw table.
+.TP
+\fBSNAT\fP
+A virtual state, matching if the original source address differs from the reply
+destination.
+.TP
+\fBDNAT\fP
+A virtual state, matching if the original destination differs from the reply
+source.
+.PP
+Statuses for \fB\-\-ctstatus\fP:
+.TP
+\fBNONE\fP
+None of the below.
+.TP
+\fBEXPECTED\fP
+This is an expected connection (i.e. a conntrack helper set it up)
+.TP
+\fBSEEN_REPLY\fP
+Conntrack has seen packets in both directions.
+.TP
+\fBASSURED\fP
+Conntrack entry should never be early-expired.
+.TP
+\fBCONFIRMED\fP
+Connection is confirmed: originating packet has left box.
+.SS cpu
+.TP
+[\fB!\fP] \fB\-\-cpu\fP \fInumber\fP
+Match cpu handling this packet. cpus are numbered from 0 to NR_CPUS-1
+Can be used in combination with RPS (Remote Packet Steering) or
+multiqueue NICs to spread network traffic on different queues.
+.PP
+Example:
+.PP
+iptables \-t nat \-A PREROUTING \-p tcp \-\-dport 80 \-m cpu \-\-cpu 0
+\-j REDIRECT \-\-to\-port 8080
+.PP
+iptables \-t nat \-A PREROUTING \-p tcp \-\-dport 80 \-m cpu \-\-cpu 1
+\-j REDIRECT \-\-to\-port 8081
+.PP
+Available since Linux 2.6.36.
+.SS dccp
+.TP
+[\fB!\fP] \fB\-\-source\-port\fP,\fB\-\-sport\fP \fIport\fP[\fB:\fP\fIport\fP]
+.TP
+[\fB!\fP] \fB\-\-destination\-port\fP,\fB\-\-dport\fP \fIport\fP[\fB:\fP\fIport\fP]
+.TP
+[\fB!\fP] \fB\-\-dccp\-types\fP \fImask\fP
+Match when the DCCP packet type is one of 'mask'. 'mask' is a comma-separated
+list of packet types. Packet types are:
+.BR "REQUEST RESPONSE DATA ACK DATAACK CLOSEREQ CLOSE RESET SYNC SYNCACK INVALID" .
+.TP
+[\fB!\fP] \fB\-\-dccp\-option\fP \fInumber\fP
+Match if DCCP option set.
.SS dscp
This module matches the 6 bit DSCP field within the TOS field in the
IP header. DSCP has superseded TOS within the IETF.
.TP
-.BI "--dscp " "value"
-Match against a numeric (decimal or hex) value [0-32].
+[\fB!\fP] \fB\-\-dscp\fP \fIvalue\fP
+Match against a numeric (decimal or hex) value [0-63].
.TP
-.BI "--dscp-class " "\fIDiffServ Class\fP"
+[\fB!\fP] \fB\-\-dscp\-class\fP \fIclass\fP
Match the DiffServ class. This value may be any of the
BE, EF, AFxx or CSx classes. It will then be converted
-into it's according numeric value.
+into its according numeric value.
+.SS ecn
+This allows you to match the ECN bits of the IPv4/IPv6 and TCP header. ECN is the Explicit Congestion Notification mechanism as specified in RFC3168
+.TP
+[\fB!\fP] \fB\-\-ecn\-tcp\-cwr\fP
+This matches if the TCP ECN CWR (Congestion Window Received) bit is set.
+.TP
+[\fB!\fP] \fB\-\-ecn\-tcp\-ece\fP
+This matches if the TCP ECN ECE (ECN Echo) bit is set.
+.TP
+[\fB!\fP] \fB\-\-ecn\-ip\-ect\fP \fInum\fP
+This matches a particular IPv4/IPv6 ECT (ECN-Capable Transport). You have to specify
+a number between `0' and `3'.
.SS esp
-This module matches the SPIs in ESP header of IPSec packets.
+This module matches the SPIs in ESP header of IPsec packets.
+.TP
+[\fB!\fP] \fB\-\-espspi\fP \fIspi\fP[\fB:\fP\fIspi\fP]
+.SS hashlimit
+\fBhashlimit\fP uses hash buckets to express a rate limiting match (like the
+\fBlimit\fP match) for a group of connections using a \fBsingle\fP iptables
+rule. Grouping can be done per-hostgroup (source and/or destination address)
+and/or per-port. It gives you the ability to express "\fIN\fP packets per time
+quantum per group" (see below for some examples).
+.PP
+A hash limit option (\fB\-\-hashlimit\-upto\fP, \fB\-\-hashlimit\-above\fP) and
+\fB\-\-hashlimit\-name\fP are required.
+.TP
+\fB\-\-hashlimit\-upto\fP \fIamount\fP[\fB/second\fP|\fB/minute\fP|\fB/hour\fP|\fB/day\fP]
+Match if the rate is below or equal to \fIamount\fP/quantum. It is specified as
+a number, with an optional time quantum suffix; the default is 3/hour.
+.TP
+\fB\-\-hashlimit\-above\fP \fIamount\fP[\fB/second\fP|\fB/minute\fP|\fB/hour\fP|\fB/day\fP]
+Match if the rate is above \fIamount\fP/quantum.
+.TP
+\fB\-\-hashlimit\-burst\fP \fIamount\fP
+Maximum initial number of packets to match: this number gets recharged by one
+every time the limit specified above is not reached, up to this number; the
+default is 5.
+.TP
+\fB\-\-hashlimit\-mode\fP {\fBsrcip\fP|\fBsrcport\fP|\fBdstip\fP|\fBdstport\fP}\fB,\fP...
+A comma-separated list of objects to take into consideration. If no
+\-\-hashlimit\-mode option is given, hashlimit acts like limit, but at the
+expensive of doing the hash housekeeping.
+.TP
+\fB\-\-hashlimit\-srcmask\fP \fIprefix\fP
+When \-\-hashlimit\-mode srcip is used, all source addresses encountered will be
+grouped according to the given prefix length and the so-created subnet will be
+subject to hashlimit. \fIprefix\fP must be between (inclusive) 0 and 32. Note
+that \-\-hashlimit\-srcmask 0 is basically doing the same thing as not specifying
+srcip for \-\-hashlimit\-mode, but is technically more expensive.
+.TP
+\fB\-\-hashlimit\-dstmask\fP \fIprefix\fP
+Like \-\-hashlimit\-srcmask, but for destination addresses.
+.TP
+\fB\-\-hashlimit\-name\fP \fIfoo\fP
+The name for the /proc/net/ipt_hashlimit/foo entry.
+.TP
+\fB\-\-hashlimit\-htable\-size\fP \fIbuckets\fP
+The number of buckets of the hash table
+.TP
+\fB\-\-hashlimit\-htable\-max\fP \fIentries\fP
+Maximum entries in the hash.
+.TP
+\fB\-\-hashlimit\-htable\-expire\fP \fImsec\fP
+After how many milliseconds do hash entries expire.
+.TP
+\fB\-\-hashlimit\-htable\-gcinterval\fP \fImsec\fP
+How many milliseconds between garbage collection intervals.
+.PP
+Examples:
.TP
-.BR "--espspi " "[!] \fIspi\fP[:\fIspi\fP]"
+matching on source host
+"1000 packets per second for every host in 192.168.0.0/16" =>
+\-s 192.168.0.0/16 \-\-hashlimit\-mode srcip \-\-hashlimit\-upto 1000/sec
+.TP
+matching on source port
+"100 packets per second for every service of 192.168.1.1" =>
+\-s 192.168.1.1 \-\-hashlimit\-mode srcport \-\-hashlimit\-upto 100/sec
+.TP
+matching on subnet
+"10000 packets per minute for every /28 subnet (groups of 8 addresses)
+in 10.0.0.0/8" =>
+\-s 10.0.0.8 \-\-hashlimit\-mask 28 \-\-hashlimit\-upto 10000/min
.SS helper
This module matches packets related to a specific conntrack-helper.
.TP
-.BI "--helper " "string"
+[\fB!\fP] \fB\-\-helper\fP \fIstring\fP
Matches packets related to the specified conntrack-helper.
.RS
.PP
string can be "ftp" for packets related to a ftp-session on default port.
-For other ports append -portnr to the value, ie. "ftp-2121".
+For other ports append \-portnr to the value, ie. "ftp\-2121".
.PP
Same rules apply for other conntrack-helpers.
.RE
.SS icmp
-This extension is loaded if `--protocol icmp' is specified. It
+This extension can be used if `\-\-protocol icmp' is specified. It
provides the following option:
.TP
-.BR "--icmp-type " "[!] \fItypename\fP"
+[\fB!\fP] \fB\-\-icmp\-type\fP {\fItype\fP[\fB/\fP\fIcode\fP]|\fItypename\fP}
This allows specification of the ICMP type, which can be a numeric
-ICMP type, or one of the ICMP type names shown by the command
+ICMP type, type/code pair, or one of the ICMP type names shown by the command
.nf
- iptables -p icmp -h
+ iptables \-p icmp \-h
.fi
+.SS iprange
+This matches on a given arbitrary range of IP addresses.
+.TP
+[\fB!\fP] \fB\-\-src\-range\fP \fIfrom\fP[\fB\-\fP\fIto\fP]
+Match source IP in the specified range.
+.TP
+[\fB!\fP] \fB\-\-dst\-range\fP \fIfrom\fP[\fB\-\fP\fIto\fP]
+Match destination IP in the specified range.
+.SS ipvs
+Match IPVS connection properties.
+.TP
+[\fB!\fP] \fB\-\-ipvs\fP
+packet belongs to an IPVS connection
+.TP
+Any of the following options implies \-\-ipvs (even negated)
+.TP
+[\fB!\fP] \fB\-\-vproto\fP \fIprotocol\fP
+VIP protocol to match; by number or name, e.g. "tcp"
+.TP
+[\fB!\fP] \fB\-\-vaddr\fP \fIaddress\fP[\fB/\fP\fImask\fP]
+VIP address to match
+.TP
+[\fB!\fP] \fB\-\-vport\fP \fIport\fP
+VIP port to match; by number or name, e.g. "http"
+.TP
+\fB\-\-vdir\fP {\fBORIGINAL\fP|\fBREPLY\fP}
+flow direction of packet
+.TP
+[\fB!\fP] \fB\-\-vmethod\fP {\fBGATE\fP|\fBIPIP\fP|\fBMASQ\fP}
+IPVS forwarding method used
+.TP
+[\fB!\fP] \fB\-\-vportctl\fP \fIport\fP
+VIP port of the controlling connection to match, e.g. 21 for FTP
.SS length
-This module matches the length of a packet against a specific value
+This module matches the length of the layer-3 payload (e.g. layer-4 packet)
+of a packet against a specific value
or range of values.
.TP
-.BR "--length " "\fIlength\fP[:\fIlength\fP]"
+[\fB!\fP] \fB\-\-length\fP \fIlength\fP[\fB:\fP\fIlength\fP]
.SS limit
This module matches at a limited rate using a token bucket filter.
-A rule using this extension will match until this limit is reached
-(unless the `!' flag is used). It can be used in combination with the
+A rule using this extension will match until this limit is reached.
+It can be used in combination with the
.B LOG
target to give limited logging, for example.
+.PP
+xt_limit has no negation support - you will have to use \-m hashlimit !
+\-\-hashlimit \fIrate\fP in this case whilst omitting \-\-hashlimit\-mode.
.TP
-.BI "--limit " "rate"
+\fB\-\-limit\fP \fIrate\fP[\fB/second\fP|\fB/minute\fP|\fB/hour\fP|\fB/day\fP]
Maximum average matching rate: specified as a number, with an optional
`/second', `/minute', `/hour', or `/day' suffix; the default is
3/hour.
.TP
-.BI "--limit-burst " "number"
+\fB\-\-limit\-burst\fP \fInumber\fP
Maximum initial number of packets to match: this number gets
recharged by one every time the limit specified above is not reached,
up to this number; the default is 5.
.SS mac
.TP
-.BR "--mac-source " "[!] \fIaddress\fP"
+[\fB!\fP] \fB\-\-mac\-source\fP \fIaddress\fP
Match source MAC address. It must be of the form XX:XX:XX:XX:XX:XX.
Note that this only makes sense for packets coming from an Ethernet device
and entering the
.B MARK
target below).
.TP
-.BR "--mark " "\fIvalue\fP[/\fImask\fP]"
-Matches packets with the given unsigned mark value (if a mask is
-specified, this is logically ANDed with the mask before the
+[\fB!\fP] \fB\-\-mark\fP \fIvalue\fP[\fB/\fP\fImask\fP]
+Matches packets with the given unsigned mark value (if a \fImask\fP is
+specified, this is logically ANDed with the \fImask\fP before the
comparison).
.SS multiport
This module matches a set of source or destination ports. Up to 15
-ports can be specified. It can only be used in conjunction with
-.B "-p tcp"
+ports can be specified. A port range (port:port) counts as two
+ports. It can only be used in conjunction with
+\fB\-p tcp\fP
or
-.BR "-p udp" .
+\fB\-p udp\fP.
.TP
-.BR "--source-ports " "\fIport\fP[,\fIport\fP[,\fIport\fP...]]"
+[\fB!\fP] \fB\-\-source\-ports\fP,\fB\-\-sports\fP \fIport\fP[\fB,\fP\fIport\fP|\fB,\fP\fIport\fP\fB:\fP\fIport\fP]...
Match if the source port is one of the given ports. The flag
-.B --sports
-is a convenient alias for this option.
+\fB\-\-sports\fP
+is a convenient alias for this option. Multiple ports or port ranges are
+separated using a comma, and a port range is specified using a colon.
+\fB53,1024:65535\fP would therefore match ports 53 and all from 1024 through
+65535.
.TP
-.BR "--destination-ports " "\fIport\fP[,\fIport\fP[,\fIport\fP...]]"
+[\fB!\fP] \fB\-\-destination\-ports\fP,\fB\-\-dports\fP \fIport\fP[\fB,\fP\fIport\fP|\fB,\fP\fIport\fP\fB:\fP\fIport\fP]...
Match if the destination port is one of the given ports. The flag
-.B --dports
+\fB\-\-dports\fP
is a convenient alias for this option.
.TP
-.BR "--ports " "\fIport\fP[,\fIport\fP[,\fIport\fP...]]"
-Match if the both the source and destination ports are equal to each
-other and to one of the given ports.
+[\fB!\fP] \fB\-\-ports\fP \fIport\fP[\fB,\fP\fIport\fP|\fB,\fP\fIport\fP\fB:\fP\fIport\fP]...
+Match if either the source or destination ports are equal to one of
+the given ports.
+.SS nfacct
+The nfacct match provides the extended accounting infrastructure for iptables.
+You have to use this match together with the standalone user-space utility
+.B nfacct(8)
+.PP
+The only option available for this match is the following:
+.TP
+\fB\-\-nfacct\-name\fP \fIname\fP
+This allows you to specify the existing object name that will be use for
+accounting the traffic that this rule-set is matching.
+.PP
+To use this extension, you have to create an accounting object:
+.IP
+nfacct add http\-traffic
+.PP
+Then, you have to attach it to the accounting object via iptables:
+.IP
+iptables \-I INPUT \-p tcp \-\-sport 80 \-m nfacct \-\-nfacct\-name http\-traffic
+.IP
+iptables \-I OUTPUT \-p tcp \-\-dport 80 \-m nfacct \-\-nfacct\-name http\-traffic
+.PP
+Then, you can check for the amount of traffic that the rules match:
+.IP
+nfacct get http\-traffic
+.IP
+{ pkts = 00000000000000000156, bytes = 00000000000000151786 } = http-traffic;
+.PP
+You can obtain
+.B nfacct(8)
+from http://www.netfilter.org or, alternatively, from the git.netfilter.org
+repository.
+.SS osf
+The osf module does passive operating system fingerprinting. This modules
+compares some data (Window Size, MSS, options and their order, TTL, DF,
+and others) from packets with the SYN bit set.
+.TP
+[\fB!\fP] \fB\-\-genre\fP \fIstring\fP
+Match an operating system genre by using a passive fingerprinting.
+.TP
+\fB\-\-ttl\fP \fIlevel\fP
+Do additional TTL checks on the packet to determine the operating system.
+\fIlevel\fP can be one of the following values:
+.IP \(bu 4
+0 - True IP address and fingerprint TTL comparison. This generally works for
+LANs.
+.IP \(bu 4
+1 - Check if the IP header's TTL is less than the fingerprint one. Works for
+globally-routable addresses.
+.IP \(bu 4
+2 - Do not compare the TTL at all.
+.TP
+\fB\-\-log\fP \fIlevel\fP
+Log determined genres into dmesg even if they do not match the desired one.
+\fIlevel\fP can be one of the following values:
+.IP \(bu 4
+0 - Log all matched or unknown signatures
+.IP \(bu 4
+1 - Log only the first one
+.IP \(bu 4
+2 - Log all known matched signatures
+.PP
+You may find something like this in syslog:
+.PP
+Windows [2000:SP3:Windows XP Pro SP1, 2000 SP3]: 11.22.33.55:4024 ->
+11.22.33.44:139 hops=3 Linux [2.5-2.6:] : 1.2.3.4:42624 -> 1.2.3.5:22 hops=4
+.PP
+OS fingerprints are loadable using the \fBnfnl_osf\fP program. To load
+fingerprints from a file, use:
+.PP
+\fBnfnl_osf -f /usr/share/xtables/pf.os\fP
+.PP
+To remove them again,
+.PP
+\fBnfnl_osf -f /usr/share/xtables/pf.os -d\fP
+.PP
+The fingerprint database can be downlaoded from
+http://www.openbsd.org/cgi-bin/cvsweb/src/etc/pf.os .
.SS owner
-This module attempts to match various characteristics of the packet
-creator, for locally-generated packets. It is only valid in the
-.B OUTPUT
-chain, and even this some packets (such as ICMP ping responses) may
-have no owner, and hence never match.
+This module attempts to match various characteristics of the packet creator,
+for locally generated packets. This match is only valid in the OUTPUT and
+POSTROUTING chains. Forwarded packets do not have any socket associated with
+them. Packets from kernel threads do have a socket, but usually no owner.
.TP
-.BI "--uid-owner " "userid"
-Matches if the packet was created by a process with the given
-effective user id.
+[\fB!\fP] \fB\-\-uid\-owner\fP \fIusername\fP
.TP
-.BI "--gid-owner " "groupid"
-Matches if the packet was created by a process with the given
-effective group id.
+[\fB!\fP] \fB\-\-uid\-owner\fP \fIuserid\fP[\fB\-\fP\fIuserid\fP]
+Matches if the packet socket's file structure (if it has one) is owned by the
+given user. You may also specify a numerical UID, or an UID range.
.TP
-.BI "--pid-owner " "processid"
-Matches if the packet was created by a process with the given
-process id.
+[\fB!\fP] \fB\-\-gid\-owner\fP \fIgroupname\fP
.TP
-.BI "--sid-owner " "sessionid"
-Matches if the packet was created by a process in the given session
-group.
+[\fB!\fP] \fB\-\-gid\-owner\fP \fIgroupid\fP[\fB\-\fP\fIgroupid\fP]
+Matches if the packet socket's file structure is owned by the given group.
+You may also specify a numerical GID, or a GID range.
.TP
-.BI "--cmd-owner " "name"
-Matches if the packet was created by a process with the given command name.
-(this option is present only if iptables was compiled under a kernel
-supporting this feature)
+[\fB!\fP] \fB\-\-socket\-exists\fP
+Matches if the packet is associated with a socket.
.SS physdev
This module matches on the bridge port input and output devices enslaved
to a bridge device. This module is a part of the infrastructure that enables
a transparent bridging IP firewall and is only useful for kernel versions
above version 2.5.44.
.TP
-.B --physdev-in name
+[\fB!\fP] \fB\-\-physdev\-in\fP \fIname\fP
Name of a bridge port via which a packet is received (only for
packets entering the
.BR INPUT ,
interface which begins with this name will match. If the packet didn't arrive
through a bridge device, this packet won't match this option, unless '!' is used.
.TP
-.B --physdev-out name
+[\fB!\fP] \fB\-\-physdev\-out\fP \fIname\fP
Name of a bridge port via which a packet is going to be sent (for packets
entering the
.BR FORWARD ,
.B OUTPUT
chains one cannot match on the bridge output port, however one can in the
.B "filter OUTPUT"
-chain. If the packet won't leave by a bridge device or it is yet unknown what
+chain. If the packet won't leave by a bridge device or if it is yet unknown what
the output device will be, then the packet won't match this option,
unless '!' is used.
.TP
-.B --physdev-is-in
+[\fB!\fP] \fB\-\-physdev\-is\-in\fP
Matches if the packet has entered through a bridge interface.
.TP
-.B --physdev-is-out
+[\fB!\fP] \fB\-\-physdev\-is\-out\fP
Matches if the packet will leave through a bridge interface.
.TP
-.B --physdev-is-bridged
+[\fB!\fP] \fB\-\-physdev\-is\-bridged\fP
Matches if the packet is being bridged and therefore is not being routed.
This is only useful in the FORWARD and POSTROUTING chains.
.SS pkttype
This module matches the link-layer packet type.
.TP
-.BI "--pkt-type " "[\fIunicast\fP|\fIbroadcast\fP|\fImulticast\fP]"
+[\fB!\fP] \fB\-\-pkt\-type\fP {\fBunicast\fP|\fBbroadcast\fP|\fBmulticast\fP}
+.SS policy
+This modules matches the policy used by IPsec for handling a packet.
+.TP
+\fB\-\-dir\fP {\fBin\fP|\fBout\fP}
+Used to select whether to match the policy used for decapsulation or the
+policy that will be used for encapsulation.
+.B in
+is valid in the
+.B PREROUTING, INPUT and FORWARD
+chains,
+.B out
+is valid in the
+.B POSTROUTING, OUTPUT and FORWARD
+chains.
+.TP
+\fB\-\-pol\fP {\fBnone\fP|\fBipsec\fP}
+Matches if the packet is subject to IPsec processing. \fB\-\-pol none\fP
+cannot be combined with \fB\-\-strict\fP.
+.TP
+\fB\-\-strict\fP
+Selects whether to match the exact policy or match if any rule of
+the policy matches the given policy.
+.PP
+For each policy element that is to be described, one can use one or more of
+the following options. When \fB\-\-strict\fP is in effect, at least one must be
+used per element.
+.TP
+[\fB!\fP] \fB\-\-reqid\fP \fIid\fP
+Matches the reqid of the policy rule. The reqid can be specified with
+.B setkey(8)
+using
+.B unique:id
+as level.
+.TP
+[\fB!\fP] \fB\-\-spi\fP \fIspi\fP
+Matches the SPI of the SA.
+.TP
+[\fB!\fP] \fB\-\-proto\fP {\fBah\fP|\fBesp\fP|\fBipcomp\fP}
+Matches the encapsulation protocol.
+.TP
+[\fB!\fP] \fB\-\-mode\fP {\fBtunnel\fP|\fBtransport\fP}
+Matches the encapsulation mode.
+.TP
+[\fB!\fP] \fB\-\-tunnel\-src\fP \fIaddr\fP[\fB/\fP\fImask\fP]
+Matches the source end-point address of a tunnel mode SA.
+Only valid with \fB\-\-mode tunnel\fP.
+.TP
+[\fB!\fP] \fB\-\-tunnel\-dst\fP \fIaddr\fP[\fB/\fP\fImask\fP]
+Matches the destination end-point address of a tunnel mode SA.
+Only valid with \fB\-\-mode tunnel\fP.
+.TP
+\fB\-\-next\fP
+Start the next element in the policy specification. Can only be used with
+\fB\-\-strict\fP.
+.SS quota
+Implements network quotas by decrementing a byte counter with each
+packet. The condition matches until the byte counter reaches zero. Behavior
+is reversed with negation (i.e. the condition does not match until the
+byte counter reaches zero).
+.TP
+[\fB!\fP] \fB\-\-quota\fP \fIbytes\fP
+The quota in bytes.
+.SS rateest
+The rate estimator can match on estimated rates as collected by the RATEEST
+target. It supports matching on absolute bps/pps values, comparing two rate
+estimators and matching on the difference between two rate estimators.
+.PP
+For a better understanding of the available options, these are all possible
+combinations:
+.\" * Absolute:
+.IP \(bu 4
+\fBrateest\fP \fIoperator\fP \fBrateest-bps\fP
+.IP \(bu 4
+\fBrateest\fP \fIoperator\fP \fBrateest-pps\fP
+.\" * Absolute + Delta:
+.IP \(bu 4
+(\fBrateest\fP minus \fBrateest-bps1\fP) \fIoperator\fP \fBrateest-bps2\fP
+.IP \(bu 4
+(\fBrateest\fP minus \fBrateest-pps1\fP) \fIoperator\fP \fBrateest-pps2\fP
+.\" * Relative:
+.IP \(bu 4
+\fBrateest1\fP \fIoperator\fP \fBrateest2\fP \fBrateest-bps\fP(without rate!)
+.IP \(bu 4
+\fBrateest1\fP \fIoperator\fP \fBrateest2\fP \fBrateest-pps\fP(without rate!)
+.\" * Relative + Delta:
+.IP \(bu 4
+(\fBrateest1\fP minus \fBrateest-bps1\fP) \fIoperator\fP
+(\fBrateest2\fP minus \fBrateest-bps2\fP)
+.IP \(bu 4
+(\fBrateest1\fP minus \fBrateest-pps1\fP) \fIoperator\fP
+(\fBrateest2\fP minus \fBrateest-pps2\fP)
+.TP
+\fB\-\-rateest\-delta\fP
+For each estimator (either absolute or relative mode), calculate the difference
+between the estimator-determined flow rate and the static value chosen with the
+BPS/PPS options. If the flow rate is higher than the specified BPS/PPS, 0 will
+be used instead of a negative value. In other words, "max(0, rateest#_rate -
+rateest#_bps)" is used.
+.TP
+[\fB!\fP] \fB\-\-rateest\-lt\fP
+Match if rate is less than given rate/estimator.
+.TP
+[\fB!\fP] \fB\-\-rateest\-gt\fP
+Match if rate is greater than given rate/estimator.
+.TP
+[\fB!\fP] \fB\-\-rateest\-eq\fP
+Match if rate is equal to given rate/estimator.
+.PP
+In the so-called "absolute mode", only one rate estimator is used and compared
+against a static value, while in "relative mode", two rate estimators are
+compared against another.
+.TP
+\fB\-\-rateest\fP \fIname\fP
+Name of the one rate estimator for absolute mode.
+.TP
+\fB\-\-rateest1\fP \fIname\fP
+.TP
+\fB\-\-rateest2\fP \fIname\fP
+The names of the two rate estimators for relative mode.
+.TP
+\fB\-\-rateest\-bps\fP [\fIvalue\fP]
+.TP
+\fB\-\-rateest\-pps\fP [\fIvalue\fP]
+.TP
+\fB\-\-rateest\-bps1\fP [\fIvalue\fP]
+.TP
+\fB\-\-rateest\-bps2\fP [\fIvalue\fP]
+.TP
+\fB\-\-rateest\-pps1\fP [\fIvalue\fP]
+.TP
+\fB\-\-rateest\-pps2\fP [\fIvalue\fP]
+Compare the estimator(s) by bytes or packets per second, and compare against
+the chosen value. See the above bullet list for which option is to be used in
+which case. A unit suffix may be used - available ones are: bit, [kmgt]bit,
+[KMGT]ibit, Bps, [KMGT]Bps, [KMGT]iBps.
+.PP
+Example: This is what can be used to route outgoing data connections from an
+FTP server over two lines based on the available bandwidth at the time the data
+connection was started:
+.PP
+# Estimate outgoing rates
+.PP
+iptables \-t mangle \-A POSTROUTING \-o eth0 \-j RATEEST \-\-rateest\-name eth0
+\-\-rateest\-interval 250ms \-\-rateest\-ewma 0.5s
+.PP
+iptables \-t mangle \-A POSTROUTING \-o ppp0 \-j RATEEST \-\-rateest\-name ppp0
+\-\-rateest\-interval 250ms \-\-rateest\-ewma 0.5s
+.PP
+# Mark based on available bandwidth
+.PP
+iptables \-t mangle \-A balance \-m conntrack \-\-ctstate NEW \-m helper \-\-helper ftp
+\-m rateest \-\-rateest\-delta \-\-rateest1 eth0 \-\-rateest\-bps1 2.5mbit \-\-rateest\-gt
+\-\-rateest2 ppp0 \-\-rateest\-bps2 2mbit \-j CONNMARK \-\-set\-mark 1
+.PP
+iptables \-t mangle \-A balance \-m conntrack \-\-ctstate NEW \-m helper \-\-helper ftp
+\-m rateest \-\-rateest\-delta \-\-rateest1 ppp0 \-\-rateest\-bps1 2mbit \-\-rateest\-gt
+\-\-rateest2 eth0 \-\-rateest\-bps2 2.5mbit \-j CONNMARK \-\-set\-mark 2
+.PP
+iptables \-t mangle \-A balance \-j CONNMARK \-\-restore\-mark
+.SS realm
+This matches the routing realm. Routing realms are used in complex routing
+setups involving dynamic routing protocols like BGP.
+.TP
+[\fB!\fP] \fB\-\-realm\fP \fIvalue\fP[\fB/\fP\fImask\fP]
+Matches a given realm number (and optionally mask). If not a number, value
+can be a named realm from /etc/iproute2/rt_realms (mask can not be used in
+that case).
+.SS recent
+Allows you to dynamically create a list of IP addresses and then match against
+that list in a few different ways.
+.PP
+For example, you can create a "badguy" list out of people attempting to connect
+to port 139 on your firewall and then DROP all future packets from them without
+considering them.
+.PP
+\fB\-\-set\fP, \fB\-\-rcheck\fP, \fB\-\-update\fP and \fB\-\-remove\fP are
+mutually exclusive.
+.TP
+\fB\-\-name\fP \fIname\fP
+Specify the list to use for the commands. If no name is given then
+\fBDEFAULT\fP will be used.
+.TP
+[\fB!\fP] \fB\-\-set\fP
+This will add the source address of the packet to the list. If the source
+address is already in the list, this will update the existing entry. This will
+always return success (or failure if \fB!\fP is passed in).
+.TP
+\fB\-\-rsource\fP
+Match/save the source address of each packet in the recent list table. This
+is the default.
+.TP
+\fB\-\-rdest\fP
+Match/save the destination address of each packet in the recent list table.
+.TP
+[\fB!\fP] \fB\-\-rcheck\fP
+Check if the source address of the packet is currently in the list.
+.TP
+[\fB!\fP] \fB\-\-update\fP
+Like \fB\-\-rcheck\fP, except it will update the "last seen" timestamp if it
+matches.
+.TP
+[\fB!\fP] \fB\-\-remove\fP
+Check if the source address of the packet is currently in the list and if so
+that address will be removed from the list and the rule will return true. If
+the address is not found, false is returned.
+.TP
+\fB\-\-seconds\fP \fIseconds\fP
+This option must be used in conjunction with one of \fB\-\-rcheck\fP or
+\fB\-\-update\fP. When used, this will narrow the match to only happen when the
+address is in the list and was seen within the last given number of seconds.
+.TP
+\fB\-\-reap\fP
+This option can only be used in conjunction with \fB\-\-seconds\fP.
+When used, this will cause entries older than the last given number of seconds
+to be purged.
+.TP
+\fB\-\-hitcount\fP \fIhits\fP
+This option must be used in conjunction with one of \fB\-\-rcheck\fP or
+\fB\-\-update\fP. When used, this will narrow the match to only happen when the
+address is in the list and packets had been received greater than or equal to
+the given value. This option may be used along with \fB\-\-seconds\fP to create
+an even narrower match requiring a certain number of hits within a specific
+time frame. The maximum value for the hitcount parameter is given by the
+"ip_pkt_list_tot" parameter of the xt_recent kernel module. Exceeding this
+value on the command line will cause the rule to be rejected.
+.TP
+\fB\-\-rttl\fP
+This option may only be used in conjunction with one of \fB\-\-rcheck\fP or
+\fB\-\-update\fP. When used, this will narrow the match to only happen when the
+address is in the list and the TTL of the current packet matches that of the
+packet which hit the \fB\-\-set\fP rule. This may be useful if you have problems
+with people faking their source address in order to DoS you via this module by
+disallowing others access to your site by sending bogus packets to you.
+.PP
+Examples:
+.IP
+iptables \-A FORWARD \-m recent \-\-name badguy \-\-rcheck \-\-seconds 60 \-j DROP
+.IP
+iptables \-A FORWARD \-p tcp \-i eth0 \-\-dport 139 \-m recent \-\-name badguy \-\-set \-j DROP
+.PP
+Steve's ipt_recent website (http://snowman.net/projects/ipt_recent/) also has
+some examples of usage.
+.PP
+\fB/proc/net/xt_recent/*\fP are the current lists of addresses and information
+about each entry of each list.
+.PP
+Each file in \fB/proc/net/xt_recent/\fP can be read from to see the current
+list or written two using the following commands to modify the list:
+.TP
+\fBecho +\fP\fIaddr\fP\fB >/proc/net/xt_recent/DEFAULT\fP
+to add \fIaddr\fP to the DEFAULT list
+.TP
+\fBecho \-\fP\fIaddr\fP\fB >/proc/net/xt_recent/DEFAULT\fP
+to remove \fIaddr\fP from the DEFAULT list
+.TP
+\fBecho / >/proc/net/xt_recent/DEFAULT\fP
+to flush the DEFAULT list (remove all entries).
+.PP
+The module itself accepts parameters, defaults shown:
+.TP
+\fBip_list_tot\fP=\fI100\fP
+Number of addresses remembered per table.
+.TP
+\fBip_pkt_list_tot\fP=\fI20\fP
+Number of packets per address remembered.
+.TP
+\fBip_list_hash_size\fP=\fI0\fP
+Hash table size. 0 means to calculate it based on ip_list_tot, default: 512.
+.TP
+\fBip_list_perms\fP=\fI0644\fP
+Permissions for /proc/net/xt_recent/* files.
+.TP
+\fBip_list_uid\fP=\fI0\fP
+Numerical UID for ownership of /proc/net/xt_recent/* files.
+.TP
+\fBip_list_gid\fP=\fI0\fP
+Numerical GID for ownership of /proc/net/xt_recent/* files.
+.SS rpfilter
+Performs a reverse path filter test on a packet.
+If a reply to the packet would be sent via the same interface
+that the packet arrived on, the packet will match.
+Note that, unlike the in-kernel rp_filter, packets protected
+by IPSec are not treated specially. Combine this match with
+the policy match if you want this.
+Also, packets arriving via the loopback interface are always permitted.
+This match can only be used in the PREROUTING chain of the raw or mangle table.
+.TP
+\fB\-\-loose\fP
+Used to specifiy that the reverse path filter test should match
+even if the selected output device is not the expected one.
+.TP
+\fB\-\-validmark\fP
+Also use the packets' nfmark value when performing the reverse path route lookup.
+.TP
+\fB\-\-accept\-local\fP
+This will permit packets arriving from the network with a source address that is also
+assigned to the local machine.
+\fB\-\-invert\fP
+This will invert the sense of the match. Instead of matching packets that passed the
+reverse path filter test, match those that have failed it.
+.PP
+Example to log and drop packets failing the reverse path filter test:
+
+iptables \-t raw \-N RPFILTER
+
+iptables \-t raw \-A RPFILTER \-m rpfilter \-j RETURN
+
+iptables \-t raw \-A RPFILTER \-m limit \-\-limit 10/minute \-j NFLOG \-\-nflog\-prefix "rpfilter drop"
+
+iptables \-t raw \-A RPFILTER \-j DROP
+
+iptables \-t raw \-A PREROUTING \-j RPFILTER
+
+Example to drop failed packets, without logging:
+
+iptables \-t raw \-A RPFILTER \-m rpfilter \-\-invert \-j DROP
+.SS sctp
+.TP
+[\fB!\fP] \fB\-\-source\-port\fP,\fB\-\-sport\fP \fIport\fP[\fB:\fP\fIport\fP]
+.TP
+[\fB!\fP] \fB\-\-destination\-port\fP,\fB\-\-dport\fP \fIport\fP[\fB:\fP\fIport\fP]
+.TP
+[\fB!\fP] \fB\-\-chunk\-types\fP {\fBall\fP|\fBany\fP|\fBonly\fP} \fIchunktype\fP[\fB:\fP\fIflags\fP] [...]
+The flag letter in upper case indicates that the flag is to match if set,
+in the lower case indicates to match if unset.
+
+Chunk types: DATA INIT INIT_ACK SACK HEARTBEAT HEARTBEAT_ACK ABORT SHUTDOWN SHUTDOWN_ACK ERROR COOKIE_ECHO COOKIE_ACK ECN_ECNE ECN_CWR SHUTDOWN_COMPLETE ASCONF ASCONF_ACK FORWARD_TSN
+
+chunk type available flags
+.br
+DATA I U B E i u b e
+.br
+ABORT T t
+.br
+SHUTDOWN_COMPLETE T t
+
+(lowercase means flag should be "off", uppercase means "on")
+.P
+Examples:
+
+iptables \-A INPUT \-p sctp \-\-dport 80 \-j DROP
+
+iptables \-A INPUT \-p sctp \-\-chunk\-types any DATA,INIT \-j DROP
+
+iptables \-A INPUT \-p sctp \-\-chunk\-types any DATA:Be \-j ACCEPT
+.SS set
+This module matches IP sets which can be defined by ipset(8).
+.TP
+[\fB!\fP] \fB\-\-match\-set\fP \fIsetname\fP \fIflag\fP[\fB,\fP\fIflag\fP]...
+where flags are the comma separated list of
+.BR "src"
+and/or
+.BR "dst"
+specifications and there can be no more than six of them. Hence the command
+.IP
+ iptables \-A FORWARD \-m set \-\-match\-set test src,dst
+.IP
+will match packets, for which (if the set type is ipportmap) the source
+address and destination port pair can be found in the specified set. If
+the set type of the specified set is single dimension (for example ipmap),
+then the command will match packets for which the source address can be
+found in the specified set.
+.PP
+The option \fB\-\-match\-set\fP can be replaced by \fB\-\-set\fP if that does
+not clash with an option of other extensions.
+.PP
+Use of -m set requires that ipset kernel support is provided, which, for
+standard kernels, is the case since Linux 2.6.39.
+.SS socket
+This matches if an open socket can be found by doing a socket lookup on the
+packet.
+.TP
+\fB\-\-transparent\fP
+Ignore non-transparent sockets.
.SS state
This module, when combined with connection tracking, allows access to
the connection tracking state for this packet.
.TP
-.BI "--state " "state"
+[\fB!\fP] \fB\-\-state\fP \fIstate\fP
Where state is a comma separated list of the connection states to
match. Possible states are
.B INVALID
meaning that the packet is starting a new connection, but is
associated with an existing connection, such as an FTP data transfer,
or an ICMP error.
+.B UNTRACKED
+meaning that the packet is not tracked at all, which happens if you use
+the NOTRACK target in raw table.
+.SS statistic
+This module matches packets based on some statistic condition.
+It supports two distinct modes settable with the
+\fB\-\-mode\fP
+option.
+.PP
+Supported options:
+.TP
+\fB\-\-mode\fP \fImode\fP
+Set the matching mode of the matching rule, supported modes are
+.B random
+and
+.B nth.
+.TP
+[\fB!\fP] \fB\-\-probability\fP \fIp\fP
+Set the probability for a packet to be randomly matched. It only works with the
+\fBrandom\fP mode. \fIp\fP must be within 0.0 and 1.0. The supported
+granularity is in 1/2147483648th increments.
+.TP
+[\fB!\fP] \fB\-\-every\fP \fIn\fP
+Match one packet every nth packet. It works only with the
+.B nth
+mode (see also the
+\fB\-\-packet\fP
+option).
+.TP
+\fB\-\-packet\fP \fIp\fP
+Set the initial counter value (0 <= p <= n\-1, default 0) for the
+.B nth
+mode.
+.SS string
+This modules matches a given string by using some pattern matching strategy. It requires a linux kernel >= 2.6.14.
+.TP
+\fB\-\-algo\fP {\fBbm\fP|\fBkmp\fP}
+Select the pattern matching strategy. (bm = Boyer-Moore, kmp = Knuth-Pratt-Morris)
+.TP
+\fB\-\-from\fP \fIoffset\fP
+Set the offset from which it starts looking for any matching. If not passed, default is 0.
+.TP
+\fB\-\-to\fP \fIoffset\fP
+Set the offset up to which should be scanned. That is, byte \fIoffset\fP-1
+(counting from 0) is the last one that is scanned.
+If not passed, default is the packet size.
+.TP
+[\fB!\fP] \fB\-\-string\fP \fIpattern\fP
+Matches the given pattern.
+.TP
+[\fB!\fP] \fB\-\-hex\-string\fP \fIpattern\fP
+Matches the given pattern in hex notation.
.SS tcp
-These extensions are loaded if `--protocol tcp' is specified. It
+These extensions can be used if `\-\-protocol tcp' is specified. It
provides the following options:
.TP
-.BR "--source-port " "[!] \fIport\fP[:\fIport\fP]"
+[\fB!\fP] \fB\-\-source\-port\fP,\fB\-\-sport\fP \fIport\fP[\fB:\fP\fIport\fP]
Source port or port range specification. This can either be a service
name or a port number. An inclusive range can also be specified,
-using the format
-.IR port : port .
+using the format \fIfirst\fP\fB:\fP\fIlast\fP.
If the first port is omitted, "0" is assumed; if the last is omitted,
"65535" is assumed.
-If the second port greater then the first they will be swapped.
+If the first port is greater than the second one they will be swapped.
The flag
-.B --sport
+\fB\-\-sport\fP
is a convenient alias for this option.
.TP
-.BR "--destination-port " "[!] \fIport\fP[:\fIport\fP]"
+[\fB!\fP] \fB\-\-destination\-port\fP,\fB\-\-dport\fP \fIport\fP[\fB:\fP\fIport\fP]
Destination port or port range specification. The flag
-.B --dport
+\fB\-\-dport\fP
is a convenient alias for this option.
.TP
-.BR "--tcp-flags " "[!] \fImask\fP \fIcomp\fP"
-Match when the TCP flags are as specified. The first argument is the
+[\fB!\fP] \fB\-\-tcp\-flags\fP \fImask\fP \fIcomp\fP
+Match when the TCP flags are as specified. The first argument \fImask\fP is the
flags which we should examine, written as a comma-separated list, and
-the second argument is a comma-separated list of flags which must be
+the second argument \fIcomp\fP is a comma-separated list of flags which must be
set. Flags are:
.BR "SYN ACK FIN RST URG PSH ALL NONE" .
Hence the command
.nf
- iptables -A FORWARD -p tcp --tcp-flags SYN,ACK,FIN,RST SYN
+ iptables \-A FORWARD \-p tcp \-\-tcp\-flags SYN,ACK,FIN,RST SYN
.fi
will only match packets with the SYN flag set, and the ACK, FIN and
RST flags unset.
.TP
-.B "[!] --syn"
-Only match TCP packets with the SYN bit set and the ACK and RST bits
+[\fB!\fP] \fB\-\-syn\fP
+Only match TCP packets with the SYN bit set and the ACK,RST and FIN bits
cleared. Such packets are used to request TCP connection initiation;
for example, blocking such packets coming in an interface will prevent
incoming TCP connections, but outgoing TCP connections will be
unaffected.
-It is equivalent to \fB--tcp-flags SYN,RST,ACK SYN\fP.
-If the "!" flag precedes the "--syn", the sense of the
+It is equivalent to \fB\-\-tcp\-flags SYN,RST,ACK,FIN SYN\fP.
+If the "!" flag precedes the "\-\-syn", the sense of the
option is inverted.
.TP
-.BR "--tcp-option " "[!] \fInumber\fP"
+[\fB!\fP] \fB\-\-tcp\-option\fP \fInumber\fP
Match if TCP option set.
-.TP
-.BR "--mss " "\fIvalue\fP[:\fIvalue\fP]"
-Match TCP SYN or SYN/ACK packets with the specified MSS value (or range),
-which control the maximum packet size for that connection.
+.SS tcpmss
+This matches the TCP MSS (maximum segment size) field of the TCP header. You can only use this on TCP SYN or SYN/ACK packets, since the MSS is only negotiated during the TCP handshake at connection startup time.
+.TP
+[\fB!\fP] \fB\-\-mss\fP \fIvalue\fP[\fB:\fP\fIvalue\fP]
+Match a given TCP MSS value or range.
+.SS time
+This matches if the packet arrival time/date is within a given range. All
+options are optional, but are ANDed when specified. All times are interpreted
+as UTC by default.
+.TP
+\fB\-\-datestart\fP \fIYYYY\fP[\fB\-\fP\fIMM\fP[\fB\-\fP\fIDD\fP[\fBT\fP\fIhh\fP[\fB:\fP\fImm\fP[\fB:\fP\fIss\fP]]]]]
+.TP
+\fB\-\-datestop\fP \fIYYYY\fP[\fB\-\fP\fIMM\fP[\fB\-\fP\fIDD\fP[\fBT\fP\fIhh\fP[\fB:\fP\fImm\fP[\fB:\fP\fIss\fP]]]]]
+Only match during the given time, which must be in ISO 8601 "T" notation.
+The possible time range is 1970-01-01T00:00:00 to 2038-01-19T04:17:07.
+.IP
+If \-\-datestart or \-\-datestop are not specified, it will default to 1970-01-01
+and 2038-01-19, respectively.
+.TP
+\fB\-\-timestart\fP \fIhh\fP\fB:\fP\fImm\fP[\fB:\fP\fIss\fP]
+.TP
+\fB\-\-timestop\fP \fIhh\fP\fB:\fP\fImm\fP[\fB:\fP\fIss\fP]
+Only match during the given daytime. The possible time range is 00:00:00 to
+23:59:59. Leading zeroes are allowed (e.g. "06:03") and correctly interpreted
+as base-10.
+.TP
+[\fB!\fP] \fB\-\-monthdays\fP \fIday\fP[\fB,\fP\fIday\fP...]
+Only match on the given days of the month. Possible values are \fB1\fP
+to \fB31\fP. Note that specifying \fB31\fP will of course not match
+on months which do not have a 31st day; the same goes for 28- or 29-day
+February.
+.TP
+[\fB!\fP] \fB\-\-weekdays\fP \fIday\fP[\fB,\fP\fIday\fP...]
+Only match on the given weekdays. Possible values are \fBMon\fP, \fBTue\fP,
+\fBWed\fP, \fBThu\fP, \fBFri\fP, \fBSat\fP, \fBSun\fP, or values from \fB1\fP
+to \fB7\fP, respectively. You may also use two-character variants (\fBMo\fP,
+\fBTu\fP, etc.).
+.TP
+\fB\-\-kerneltz\fP
+Use the kernel timezone instead of UTC to determine whether a packet meets the
+time regulations.
+.PP
+About kernel timezones: Linux keeps the system time in UTC, and always does so.
+On boot, system time is initialized from a referential time source. Where this
+time source has no timezone information, such as the x86 CMOS RTC, UTC will be
+assumed. If the time source is however not in UTC, userspace should provide the
+correct system time and timezone to the kernel once it has the information.
+.PP
+Local time is a feature on top of the (timezone independent) system time. Each
+process has its own idea of local time, specified via the TZ environment
+variable. The kernel also has its own timezone offset variable. The TZ
+userspace environment variable specifies how the UTC-based system time is
+displayed, e.g. when you run date(1), or what you see on your desktop clock.
+The TZ string may resolve to different offsets at different dates, which is
+what enables the automatic time-jumping in userspace. when DST changes. The
+kernel's timezone offset variable is used when it has to convert between
+non-UTC sources, such as FAT filesystems, to UTC (since the latter is what the
+rest of the system uses).
+.PP
+The caveat with the kernel timezone is that Linux distributions may ignore to
+set the kernel timezone, and instead only set the system time. Even if a
+particular distribution does set the timezone at boot, it is usually does not
+keep the kernel timezone offset - which is what changes on DST - up to date.
+ntpd will not touch the kernel timezone, so running it will not resolve the
+issue. As such, one may encounter a timezone that is always +0000, or one that
+is wrong half of the time of the year. As such, \fBusing \-\-kerneltz is highly
+discouraged.\fP
+.PP
+EXAMPLES. To match on weekends, use:
+.IP
+\-m time \-\-weekdays Sa,Su
+.PP
+Or, to match (once) on a national holiday block:
+.IP
+\-m time \-\-datestart 2007\-12\-24 \-\-datestop 2007\-12\-27
+.PP
+Since the stop time is actually inclusive, you would need the following stop
+time to not match the first second of the new day:
+.IP
+\-m time \-\-datestart 2007\-01\-01T17:00 \-\-datestop 2007\-01\-01T23:59:59
+.PP
+During lunch hour:
+.IP
+\-m time \-\-timestart 12:30 \-\-timestop 13:30
+.PP
+The fourth Friday in the month:
+.IP
+\-m time \-\-weekdays Fr \-\-monthdays 22,23,24,25,26,27,28
+.PP
+(Note that this exploits a certain mathematical property. It is not possible to
+say "fourth Thursday OR fourth Friday" in one rule. It is possible with
+multiple rules, though.)
.SS tos
-This module matches the 8 bits of Type of Service field in the IP
-header (ie. including the precedence bits).
-.TP
-.BI "--tos " "tos"
-The argument is either a standard name, (use
-.br
- iptables -m tos -h
-.br
-to see the list), or a numeric value to match.
+This module matches the 8-bit Type of Service field in the IPv4 header (i.e.
+including the "Precedence" bits) or the (also 8-bit) Priority field in the IPv6
+header.
+.TP
+[\fB!\fP] \fB\-\-tos\fP \fIvalue\fP[\fB/\fP\fImask\fP]
+Matches packets with the given TOS mark value. If a mask is specified, it is
+logically ANDed with the TOS mark before the comparison.
+.TP
+[\fB!\fP] \fB\-\-tos\fP \fIsymbol\fP
+You can specify a symbolic name when using the tos match for IPv4. The list of
+recognized TOS names can be obtained by calling iptables with \fB\-m tos \-h\fP.
+Note that this implies a mask of 0x3F, i.e. all but the ECN bits.
.SS ttl
This module matches the time to live field in the IP header.
.TP
-.BI "--ttl " "ttl"
+[\fB!\fP] \fB\-\-ttl\-eq\fP \fIttl\fP
Matches the given TTL value.
+.TP
+\fB\-\-ttl\-gt\fP \fIttl\fP
+Matches if TTL is greater than the given TTL value.
+.TP
+\fB\-\-ttl\-lt\fP \fIttl\fP
+Matches if TTL is less than the given TTL value.
+.SS u32
+U32 tests whether quantities of up to 4 bytes extracted from a packet have
+specified values. The specification of what to extract is general enough to
+find data at given offsets from tcp headers or payloads.
+.TP
+[\fB!\fP] \fB\-\-u32\fP \fItests\fP
+The argument amounts to a program in a small language described below.
+.IP
+tests := location "=" value | tests "&&" location "=" value
+.IP
+value := range | value "," range
+.IP
+range := number | number ":" number
+.PP
+a single number, \fIn\fP, is interpreted the same as \fIn:n\fP. \fIn:m\fP is
+interpreted as the range of numbers \fB>=n\fP and \fB<=m\fP.
+.IP "" 4
+location := number | location operator number
+.IP "" 4
+operator := "&" | "<<" | ">>" | "@"
+.PP
+The operators \fB&\fP, \fB<<\fP, \fB>>\fP and \fB&&\fP mean the same as in C.
+The \fB=\fP is really a set membership operator and the value syntax describes
+a set. The \fB@\fP operator is what allows moving to the next header and is
+described further below.
+.PP
+There are currently some artificial implementation limits on the size of the
+tests:
+.IP " *"
+no more than 10 of "\fB=\fP" (and 9 "\fB&&\fP"s) in the u32 argument
+.IP " *"
+no more than 10 ranges (and 9 commas) per value
+.IP " *"
+no more than 10 numbers (and 9 operators) per location
+.PP
+To describe the meaning of location, imagine the following machine that
+interprets it. There are three registers:
+.IP
+A is of type \fBchar *\fP, initially the address of the IP header
+.IP
+B and C are unsigned 32 bit integers, initially zero
+.PP
+The instructions are:
+.IP
+number B = number;
+.IP
+C = (*(A+B)<<24) + (*(A+B+1)<<16) + (*(A+B+2)<<8) + *(A+B+3)
+.IP
+&number C = C & number
+.IP
+<< number C = C << number
+.IP
+>> number C = C >> number
+.IP
+@number A = A + C; then do the instruction number
+.PP
+Any access of memory outside [skb\->data,skb\->end] causes the match to fail.
+Otherwise the result of the computation is the final value of C.
+.PP
+Whitespace is allowed but not required in the tests. However, the characters
+that do occur there are likely to require shell quoting, so it is a good idea
+to enclose the arguments in quotes.
+.PP
+Example:
+.IP
+match IP packets with total length >= 256
+.IP
+The IP header contains a total length field in bytes 2-3.
+.IP
+\-\-u32 "\fB0 & 0xFFFF = 0x100:0xFFFF\fP"
+.IP
+read bytes 0-3
+.IP
+AND that with 0xFFFF (giving bytes 2-3), and test whether that is in the range
+[0x100:0xFFFF]
+.PP
+Example: (more realistic, hence more complicated)
+.IP
+match ICMP packets with icmp type 0
+.IP
+First test that it is an ICMP packet, true iff byte 9 (protocol) = 1
+.IP
+\-\-u32 "\fB6 & 0xFF = 1 &&\fP ...
+.IP
+read bytes 6-9, use \fB&\fP to throw away bytes 6-8 and compare the result to
+1. Next test that it is not a fragment. (If so, it might be part of such a
+packet but we cannot always tell.) N.B.: This test is generally needed if you
+want to match anything beyond the IP header. The last 6 bits of byte 6 and all
+of byte 7 are 0 iff this is a complete packet (not a fragment). Alternatively,
+you can allow first fragments by only testing the last 5 bits of byte 6.
+.IP
+ ... \fB4 & 0x3FFF = 0 &&\fP ...
+.IP
+Last test: the first byte past the IP header (the type) is 0. This is where we
+have to use the @syntax. The length of the IP header (IHL) in 32 bit words is
+stored in the right half of byte 0 of the IP header itself.
+.IP
+ ... \fB0 >> 22 & 0x3C @ 0 >> 24 = 0\fP"
+.IP
+The first 0 means read bytes 0-3, \fB>>22\fP means shift that 22 bits to the
+right. Shifting 24 bits would give the first byte, so only 22 bits is four
+times that plus a few more bits. \fB&3C\fP then eliminates the two extra bits
+on the right and the first four bits of the first byte. For instance, if IHL=5,
+then the IP header is 20 (4 x 5) bytes long. In this case, bytes 0-1 are (in
+binary) xxxx0101 yyzzzzzz, \fB>>22\fP gives the 10 bit value xxxx0101yy and
+\fB&3C\fP gives 010100. \fB@\fP means to use this number as a new offset into
+the packet, and read four bytes starting from there. This is the first 4 bytes
+of the ICMP payload, of which byte 0 is the ICMP type. Therefore, we simply
+shift the value 24 to the right to throw out all but the first byte and compare
+the result with 0.
+.PP
+Example:
+.IP
+TCP payload bytes 8-12 is any of 1, 2, 5 or 8
+.IP
+First we test that the packet is a tcp packet (similar to ICMP).
+.IP
+\-\-u32 "\fB6 & 0xFF = 6 &&\fP ...
+.IP
+Next, test that it is not a fragment (same as above).
+.IP
+ ... \fB0 >> 22 & 0x3C @ 12 >> 26 & 0x3C @ 8 = 1,2,5,8\fP"
+.IP
+\fB0>>22&3C\fP as above computes the number of bytes in the IP header. \fB@\fP
+makes this the new offset into the packet, which is the start of the TCP
+header. The length of the TCP header (again in 32 bit words) is the left half
+of byte 12 of the TCP header. The \fB12>>26&3C\fP computes this length in bytes
+(similar to the IP header before). "@" makes this the new offset, which is the
+start of the TCP payload. Finally, 8 reads bytes 8-12 of the payload and
+\fB=\fP checks whether the result is any of 1, 2, 5 or 8.
.SS udp
-These extensions are loaded if `--protocol udp' is specified. It
+These extensions can be used if `\-\-protocol udp' is specified. It
provides the following options:
.TP
-.BR "--source-port " "[!] \fIport\fP[:\fIport\fP]"
+[\fB!\fP] \fB\-\-source\-port\fP,\fB\-\-sport\fP \fIport\fP[\fB:\fP\fIport\fP]
Source port or port range specification.
See the description of the
-.B --source-port
+\fB\-\-source\-port\fP
option of the TCP extension for details.
.TP
-.BR "--destination-port " "[!] \fIport\fP[:\fIport\fP]"
+[\fB!\fP] \fB\-\-destination\-port\fP,\fB\-\-dport\fP \fIport\fP[\fB:\fP\fIport\fP]
Destination port or port range specification.
See the description of the
-.B --destination-port
+\fB\-\-destination\-port\fP
option of the TCP extension for details.
.SS unclean
This module takes no options, but attempts to match packets which seem
.SH TARGET EXTENSIONS
iptables can use extended target modules: the following are included
in the standard distribution.
+.\" @TARGET@
+.SS AUDIT
+This target allows to create audit records for packets hitting the target.
+It can be used to record accepted, dropped, and rejected packets. See
+auditd(8) for additional details.
+.TP
+\fB\-\-type\fP {\fBaccept\fP|\fBdrop\fP|\fBreject\fP}
+Set type of audit record.
+.PP
+Example:
+.IP
+iptables \-N AUDIT_DROP
+.IP
+iptables \-A AUDIT_DROP \-j AUDIT \-\-type drop
+.IP
+iptables \-A AUDIT_DROP \-j DROP
+.SS CHECKSUM
+This target allows to selectively work around broken/old applications.
+It can only be used in the mangle table.
+.TP
+\fB\-\-checksum\-fill\fP
+Compute and fill in the checksum in a packet that lacks a checksum.
+This is particularly useful, if you need to work around old applications
+such as dhcp clients, that do not work well with checksum offloads,
+but don't want to disable checksum offload in your device.
+.SS CLASSIFY
+This module allows you to set the skb\->priority value (and thus classify the packet into a specific CBQ class).
+.TP
+\fB\-\-set\-class\fP \fImajor\fP\fB:\fP\fIminor\fP
+Set the major and minor class value. The values are always interpreted as
+hexadecimal even if no 0x prefix is given.
+.SS CLUSTERIP
+This module allows you to configure a simple cluster of nodes that share
+a certain IP and MAC address without an explicit load balancer in front of
+them. Connections are statically distributed between the nodes in this
+cluster.
+.TP
+\fB\-\-new\fP
+Create a new ClusterIP. You always have to set this on the first rule
+for a given ClusterIP.
+.TP
+\fB\-\-hashmode\fP \fImode\fP
+Specify the hashing mode. Has to be one of
+\fBsourceip\fP, \fBsourceip\-sourceport\fP, \fBsourceip\-sourceport\-destport\fP.
+.TP
+\fB\-\-clustermac\fP \fImac\fP
+Specify the ClusterIP MAC address. Has to be a link\-layer multicast address
+.TP
+\fB\-\-total\-nodes\fP \fInum\fP
+Number of total nodes within this cluster.
+.TP
+\fB\-\-local\-node\fP \fInum\fP
+Local node number within this cluster.
+.TP
+\fB\-\-hash\-init\fP \fIrnd\fP
+Specify the random seed used for hash initialization.
+.SS CONNMARK
+This module sets the netfilter mark value associated with a connection. The
+mark is 32 bits wide.
+.TP
+\fB\-\-set\-xmark\fP \fIvalue\fP[\fB/\fP\fImask\fP]
+Zero out the bits given by \fImask\fP and XOR \fIvalue\fP into the ctmark.
+.TP
+\fB\-\-save\-mark\fP [\fB\-\-nfmask\fP \fInfmask\fP] [\fB\-\-ctmask\fP \fIctmask\fP]
+Copy the packet mark (nfmark) to the connection mark (ctmark) using the given
+masks. The new nfmark value is determined as follows:
+.IP
+ctmark = (ctmark & ~ctmask) ^ (nfmark & nfmask)
+.IP
+i.e. \fIctmask\fP defines what bits to clear and \fInfmask\fP what bits of the
+nfmark to XOR into the ctmark. \fIctmask\fP and \fInfmask\fP default to
+0xFFFFFFFF.
+.TP
+\fB\-\-restore\-mark\fP [\fB\-\-nfmask\fP \fInfmask\fP] [\fB\-\-ctmask\fP \fIctmask\fP]
+Copy the connection mark (ctmark) to the packet mark (nfmark) using the given
+masks. The new ctmark value is determined as follows:
+.IP
+nfmark = (nfmark & ~\fInfmask\fP) ^ (ctmark & \fIctmask\fP);
+.IP
+i.e. \fInfmask\fP defines what bits to clear and \fIctmask\fP what bits of the
+ctmark to XOR into the nfmark. \fIctmask\fP and \fInfmask\fP default to
+0xFFFFFFFF.
+.IP
+\fB\-\-restore\-mark\fP is only valid in the \fBmangle\fP table.
+.PP
+The following mnemonics are available for \fB\-\-set\-xmark\fP:
+.TP
+\fB\-\-and\-mark\fP \fIbits\fP
+Binary AND the ctmark with \fIbits\fP. (Mnemonic for \fB\-\-set\-xmark
+0/\fP\fIinvbits\fP, where \fIinvbits\fP is the binary negation of \fIbits\fP.)
+.TP
+\fB\-\-or\-mark\fP \fIbits\fP
+Binary OR the ctmark with \fIbits\fP. (Mnemonic for \fB\-\-set\-xmark\fP
+\fIbits\fP\fB/\fP\fIbits\fP.)
+.TP
+\fB\-\-xor\-mark\fP \fIbits\fP
+Binary XOR the ctmark with \fIbits\fP. (Mnemonic for \fB\-\-set\-xmark\fP
+\fIbits\fP\fB/0\fP.)
+.TP
+\fB\-\-set\-mark\fP \fIvalue\fP[\fB/\fP\fImask\fP]
+Set the connection mark. If a mask is specified then only those bits set in the
+mask are modified.
+.TP
+\fB\-\-save\-mark\fP [\fB\-\-mask\fP \fImask\fP]
+Copy the nfmark to the ctmark. If a mask is specified, only those bits are
+copied.
+.TP
+\fB\-\-restore\-mark\fP [\fB\-\-mask\fP \fImask\fP]
+Copy the ctmark to the nfmark. If a mask is specified, only those bits are
+copied. This is only valid in the \fBmangle\fP table.
+.SS CONNSECMARK
+This module copies security markings from packets to connections
+(if unlabeled), and from connections back to packets (also only
+if unlabeled). Typically used in conjunction with SECMARK, it is
+valid in the
+.B security
+table (for backwards compatibility with older kernels, it is also
+valid in the
+.B mangle
+table).
+.TP
+\fB\-\-save\fP
+If the packet has a security marking, copy it to the connection
+if the connection is not marked.
+.TP
+\fB\-\-restore\fP
+If the packet does not have a security marking, and the connection
+does, copy the security marking from the connection to the packet.
+
+.SS CT
+The CT target allows to set parameters for a packet or its associated
+connection. The target attaches a "template" connection tracking entry to
+the packet, which is then used by the conntrack core when initializing
+a new ct entry. This target is thus only valid in the "raw" table.
+.TP
+\fB\-\-notrack\fP
+Disables connection tracking for this packet.
+.TP
+\fB\-\-helper\fP \fIname\fP
+Use the helper identified by \fIname\fP for the connection. This is more
+flexible than loading the conntrack helper modules with preset ports.
+.TP
+\fB\-\-ctevents\fP \fIevent\fP[\fB,\fP...]
+Only generate the specified conntrack events for this connection. Possible
+event types are: \fBnew\fP, \fBrelated\fP, \fBdestroy\fP, \fBreply\fP,
+\fBassured\fP, \fBprotoinfo\fP, \fBhelper\fP, \fBmark\fP (this refers to
+the ctmark, not nfmark), \fBnatseqinfo\fP, \fBsecmark\fP (ctsecmark).
+.TP
+\fB\-\-expevents\fP \fIevent\fP[\fB,\fP...]
+Only generate the specified expectation events for this connection.
+Possible event types are: \fBnew\fP.
+.TP
+\fB\-\-zone\fP \fIid\fP
+Assign this packet to zone \fIid\fP and only have lookups done in that zone.
+By default, packets have zone 0.
.SS DNAT
This target is only valid in the
.B nat
also be mangled), and rules should cease being examined. It takes one
type of option:
.TP
-.BR "--to-destination " "\fIipaddr\fP[-\fIipaddr\fP][:\fIport\fP-\fIport\fP]"
+\fB\-\-to\-destination\fP [\fIipaddr\fP[\fB\-\fP\fIipaddr\fP]][\fB:\fP\fIport\fP[\fB\-\fP\fIport\fP]]
which can specify a single new destination IP address, an inclusive
range of IP addresses, and optionally, a port range (which is only
valid if the rule also specifies
-.B "-p tcp"
+\fB\-p tcp\fP
or
-.BR "-p udp" ).
+\fB\-p udp\fP).
If no port range is specified, then the destination port will never be
-modified.
-.RS
-.PP
-You can add several --to-destination options. If you specify more
-than one destination address, either via an address range or multiple
---to-destination options, a simple round-robin (one after another in
-cycle) load balancing takes place between these adresses.
+modified. If no IP address is specified then only the destination port
+will be modified.
+
+In Kernels up to 2.6.10 you can add several \-\-to\-destination options. For
+those kernels, if you specify more than one destination address, either via an
+address range or multiple \-\-to\-destination options, a simple round-robin (one
+after another in cycle) load balancing takes place between these addresses.
+Later Kernels (>= 2.6.11-rc1) don't have the ability to NAT to multiple ranges
+anymore.
+.TP
+\fB\-\-random\fP
+If option
+\fB\-\-random\fP
+is used then port mapping will be randomized (kernel >= 2.6.22).
+.TP
+\fB\-\-persistent\fP
+Gives a client the same source-/destination-address for each connection.
+This supersedes the SAME target. Support for persistent mappings is available
+from 2.6.29-rc2.
.SS DSCP
This target allows to alter the value of the DSCP bits within the TOS
header of the IPv4 packet. As this manipulates a packet, it can only
be used in the mangle table.
.TP
-.BI "--set-dscp " "value"
+\fB\-\-set\-dscp\fP \fIvalue\fP
Set the DSCP field to a numerical value (can be decimal or hex)
.TP
-.BI "--set-dscp-class " "class"
+\fB\-\-set\-dscp\-class\fP \fIclass\fP
Set the DSCP field to a DiffServ class.
.SS ECN
This target allows to selectively work around known ECN blackholes.
It can only be used in the mangle table.
.TP
-.BI "--ecn-tcp-remove"
+\fB\-\-ecn\-tcp\-remove\fP
Remove all ECN bits from the TCP header. Of course, it can only be used
in conjunction with
-.BR "-p tcp" .
+\fB\-p tcp\fP.
+.SS IDLETIMER
+This target can be used to identify when interfaces have been idle for a
+certain period of time. Timers are identified by labels and are created when
+a rule is set with a new label. The rules also take a timeout value (in
+seconds) as an option. If more than one rule uses the same timer label, the
+timer will be restarted whenever any of the rules get a hit. One entry for
+each timer is created in sysfs. This attribute contains the timer remaining
+for the timer to expire. The attributes are located under the xt_idletimer
+class:
+.PP
+/sys/class/xt_idletimer/timers/<label>
+.PP
+When the timer expires, the target module sends a sysfs notification to the
+userspace, which can then decide what to do (eg. disconnect to save power).
+.TP
+\fB\-\-timeout\fP \fIamount\fP
+This is the time in seconds that will trigger the notification.
+.TP
+\fB\-\-label\fP \fIstring\fP
+This is a unique identifier for the timer. The maximum length for the
+label string is 27 characters.
.SS LOG
Turn on kernel logging of matching packets. When this option is set
for a rule, the Linux kernel will print some information on all
separate rules with the same matching criteria, first using target LOG
then DROP (or REJECT).
.TP
-.BI "--log-level " "level"
+\fB\-\-log\-level\fP \fIlevel\fP
Level of logging (numeric or see \fIsyslog.conf\fP(5)).
.TP
-.BI "--log-prefix " "prefix"
+\fB\-\-log\-prefix\fP \fIprefix\fP
Prefix log messages with the specified prefix; up to 29 letters long,
and useful for distinguishing messages in the logs.
.TP
-.B --log-tcp-sequence
+\fB\-\-log\-tcp\-sequence\fP
Log TCP sequence numbers. This is a security risk if the log is
readable by users.
.TP
-.B --log-tcp-options
+\fB\-\-log\-tcp\-options\fP
Log options from the TCP packet header.
.TP
-.B --log-ip-options
+\fB\-\-log\-ip\-options\fP
Log options from the IP packet header.
+.TP
+\fB\-\-log\-uid\fP
+Log the userid of the process which generated the packet.
.SS MARK
-This is used to set the netfilter mark value associated with the
-packet. It is only valid in the
-.B mangle
-table. It can for example be used in conjunction with iproute2.
+This target is used to set the Netfilter mark value associated with the packet.
+It can, for example, be used in conjunction with routing based on fwmark (needs
+iproute2). If you plan on doing so, note that the mark needs to be set in the
+PREROUTING chain of the mangle table to affect routing.
+The mark field is 32 bits wide.
+.TP
+\fB\-\-set\-xmark\fP \fIvalue\fP[\fB/\fP\fImask\fP]
+Zeroes out the bits given by \fImask\fP and XORs \fIvalue\fP into the packet
+mark ("nfmark"). If \fImask\fP is omitted, 0xFFFFFFFF is assumed.
+.TP
+\fB\-\-set\-mark\fP \fIvalue\fP[\fB/\fP\fImask\fP]
+Zeroes out the bits given by \fImask\fP and ORs \fIvalue\fP into the packet
+mark. If \fImask\fP is omitted, 0xFFFFFFFF is assumed.
+.PP
+The following mnemonics are available:
+.TP
+\fB\-\-and\-mark\fP \fIbits\fP
+Binary AND the nfmark with \fIbits\fP. (Mnemonic for \fB\-\-set\-xmark
+0/\fP\fIinvbits\fP, where \fIinvbits\fP is the binary negation of \fIbits\fP.)
+.TP
+\fB\-\-or\-mark\fP \fIbits\fP
+Binary OR the nfmark with \fIbits\fP. (Mnemonic for \fB\-\-set\-xmark\fP
+\fIbits\fP\fB/\fP\fIbits\fP.)
.TP
-.BI "--set-mark " "mark"
+\fB\-\-xor\-mark\fP \fIbits\fP
+Binary XOR the nfmark with \fIbits\fP. (Mnemonic for \fB\-\-set\-xmark\fP
+\fIbits\fP\fB/0\fP.)
.SS MASQUERADE
This target is only valid in the
.B nat
.I forgotten
when the interface goes down. This is the correct behavior when the
next dialup is unlikely to have the same interface address (and hence
-any established connections are lost anyway). It takes one option:
+any established connections are lost anyway).
.TP
-.BR "--to-ports " "\fIport\fP[-\fIport\fP]"
+\fB\-\-to\-ports\fP \fIport\fP[\fB\-\fP\fIport\fP]
This specifies a range of source ports to use, overriding the default
.B SNAT
source port-selection heuristics (see above). This is only valid
if the rule also specifies
-.B "-p tcp"
+\fB\-p tcp\fP
or
-.BR "-p udp" .
+\fB\-p udp\fP.
+.TP
+\fB\-\-random\fP
+Randomize source port mapping
+If option
+\fB\-\-random\fP
+is used then port mapping will be randomized (kernel >= 2.6.21).
+.RS
+.PP
.SS MIRROR
This is an experimental demonstration target which inverts the source
and destination fields in the IP header and retransmits the packet.
.B NOT
seen by any packet filtering chains, connection tracking or NAT, to
avoid loops and other problems.
+.SS NETMAP
+This target allows you to statically map a whole network of addresses onto
+another network of addresses. It can only be used from rules in the
+.B nat
+table.
+.TP
+\fB\-\-to\fP \fIaddress\fP[\fB/\fP\fImask\fP]
+Network address to map to. The resulting address will be constructed in the
+following way: All 'one' bits in the mask are filled in from the new `address'.
+All bits that are zero in the mask are filled in from the original address.
+.SS NFLOG
+This target provides logging of matching packets. When this target is
+set for a rule, the Linux kernel will pass the packet to the loaded
+logging backend to log the packet. This is usually used in combination
+with nfnetlink_log as logging backend, which will multicast the packet
+through a
+.IR netlink
+socket to the specified multicast group. One or more userspace processes
+may subscribe to the group to receive the packets. Like LOG, this is a
+non-terminating target, i.e. rule traversal continues at the next rule.
+.TP
+\fB\-\-nflog\-group\fP \fInlgroup\fP
+The netlink group (0 - 2^16\-1) to which packets are (only applicable for
+nfnetlink_log). The default value is 0.
+.TP
+\fB\-\-nflog\-prefix\fP \fIprefix\fP
+A prefix string to include in the log message, up to 64 characters
+long, useful for distinguishing messages in the logs.
+.TP
+\fB\-\-nflog\-range\fP \fIsize\fP
+The number of bytes to be copied to userspace (only applicable for
+nfnetlink_log). nfnetlink_log instances may specify their own
+range, this option overrides it.
+.TP
+\fB\-\-nflog\-threshold\fP \fIsize\fP
+Number of packets to queue inside the kernel before sending them
+to userspace (only applicable for nfnetlink_log). Higher values
+result in less overhead per packet, but increase delay until the
+packets reach userspace. The default value is 1.
+.BR
+.SS NFQUEUE
+This target is an extension of the QUEUE target. As opposed to QUEUE, it allows
+you to put a packet into any specific queue, identified by its 16-bit queue
+number.
+It can only be used with Kernel versions 2.6.14 or later, since it requires
+the
+.B
+nfnetlink_queue
+kernel support. The \fBqueue-balance\fP option was added in Linux 2.6.31,
+\fBqueue-bypass\fP in 2.6.39.
+.TP
+\fB\-\-queue\-num\fP \fIvalue\fP
+This specifies the QUEUE number to use. Valid queue numbers are 0 to 65535. The default value is 0.
+.PP
+.TP
+\fB\-\-queue\-balance\fP \fIvalue\fP\fB:\fP\fIvalue\fP
+This specifies a range of queues to use. Packets are then balanced across the given queues.
+This is useful for multicore systems: start multiple instances of the userspace program on
+queues x, x+1, .. x+n and use "\-\-queue\-balance \fIx\fP\fB:\fP\fIx+n\fP".
+Packets belonging to the same connection are put into the same nfqueue.
+.PP
+.TP
+\fB\-\-queue\-bypass\fP
+By default, if no userspace program is listening on an NFQUEUE, then all packets that are to be queued
+are dropped. When this option is used, the NFQUEUE rule is silently bypassed instead. The packet
+will move on to the next rule.
+.SS NOTRACK
+This target disables connection tracking for all packets matching that rule.
+.PP
+It can only be used in the
+.B raw
+table.
+.SS RATEEST
+The RATEEST target collects statistics, performs rate estimation calculation
+and saves the results for later evaluation using the \fBrateest\fP match.
+.TP
+\fB\-\-rateest\-name\fP \fIname\fP
+Count matched packets into the pool referred to by \fIname\fP, which is freely
+choosable.
+.TP
+\fB\-\-rateest\-interval\fP \fIamount\fP{\fBs\fP|\fBms\fP|\fBus\fP}
+Rate measurement interval, in seconds, milliseconds or microseconds.
+.TP
+\fB\-\-rateest\-ewmalog\fP \fIvalue\fP
+Rate measurement averaging time constant.
.SS REDIRECT
This target is only valid in the
.B nat
and
.B OUTPUT
chains, and user-defined chains which are only called from those
-chains. It alters the destination IP address to send the packet to
-the machine itself (locally-generated packets are mapped to the
-127.0.0.1 address). It takes one option:
+chains. It redirects the packet to the machine itself by changing the
+destination IP to the primary address of the incoming interface
+(locally-generated packets are mapped to the 127.0.0.1 address).
.TP
-.BR "--to-ports " "\fIport\fP[-\fIport\fP]"
+\fB\-\-to\-ports\fP \fIport\fP[\fB\-\fP\fIport\fP]
This specifies a destination port or range of ports to use: without
this, the destination port is never altered. This is only valid
if the rule also specifies
-.B "-p tcp"
+\fB\-p tcp\fP
or
-.BR "-p udp" .
+\fB\-p udp\fP.
+.TP
+\fB\-\-random\fP
+If option
+\fB\-\-random\fP
+is used then port mapping will be randomized (kernel >= 2.6.22).
+.RS
+.PP
.SS REJECT
This is used to send back an error packet in response to the matched
packet: otherwise it is equivalent to
chains. The following option controls the nature of the error packet
returned:
.TP
-.BI "--reject-with " "type"
+\fB\-\-reject\-with\fP \fItype\fP
The type given can be
-.nf
-.B " icmp-net-unreachable"
-.B " icmp-host-unreachable"
-.B " icmp-port-unreachable"
-.B " icmp-proto-unreachable"
-.B " icmp-net-prohibited"
-.B " icmp-host-prohibited or"
-.B " icmp-admin-prohibited (*)"
-.fi
-which return the appropriate ICMP error message (\fBport-unreachable\fP is
+\fBicmp\-net\-unreachable\fP,
+\fBicmp\-host\-unreachable\fP,
+\fBicmp\-port\-unreachable\fP,
+\fBicmp\-proto\-unreachable\fP,
+\fBicmp\-net\-prohibited\fP,
+\fBicmp\-host\-prohibited\fP or
+\fBicmp\-admin\-prohibited\fP (*)
+which return the appropriate ICMP error message (\fBport\-unreachable\fP is
the default). The option
-.B tcp-reset
+\fBtcp\-reset\fP
can be used on rules which only match the TCP protocol: this causes a
TCP RST packet to be sent back. This is mainly useful for blocking
.I ident
(113/tcp) probes which frequently occur when sending mail to broken mail
hosts (which won't accept your mail otherwise).
-.RS
.PP
-(*) Using icmp-admin-prohibited with kernels that do not support it will result in a plain DROP instead of REJECT
+(*) Using icmp\-admin\-prohibited with kernels that do not support it will result in a plain DROP instead of REJECT
+.SS SAME
+Similar to SNAT/DNAT depending on chain: it takes a range of addresses
+(`\-\-to 1.2.3.4\-1.2.3.7') and gives a client the same
+source-/destination-address for each connection.
+.PP
+N.B.: The DNAT target's \fB\-\-persistent\fP option replaced the SAME target.
+.TP
+\fB\-\-to\fP \fIipaddr\fP[\fB\-\fP\fIipaddr\fP]
+Addresses to map source to. May be specified more than once for
+multiple ranges.
+.TP
+\fB\-\-nodst\fP
+Don't use the destination-ip in the calculations when selecting the
+new source-ip
+.TP
+\fB\-\-random\fP
+Port mapping will be forcibly randomized to avoid attacks based on
+port prediction (kernel >= 2.6.21).
+.SS SECMARK
+This is used to set the security mark value associated with the
+packet for use by security subsystems such as SELinux. It is
+valid in the
+.B security
+table (for backwards compatibility with older kernels, it is also
+valid in the
+.B mangle
+table). The mark is 32 bits wide.
+.TP
+\fB\-\-selctx\fP \fIsecurity_context\fP
+.SS SET
+This modules adds and/or deletes entries from IP sets which can be defined
+by ipset(8).
+.TP
+\fB\-\-add\-set\fP \fIsetname\fP \fIflag\fP[\fB,\fP\fIflag\fP...]
+add the address(es)/port(s) of the packet to the sets
+.TP
+\fB\-\-del\-set\fP \fIsetname\fP \fIflag\fP[\fB,\fP\fIflag\fP...]
+delete the address(es)/port(s) of the packet from the sets
+.IP
+where flags are
+.BR "src"
+and/or
+.BR "dst"
+specifications and there can be no more than six of them.
+.TP
+\fB\-\-timeout\fP \fIvalue\fP
+when adding entry, the timeout value to use instead of the default
+one from the set definition
+.TP
+\fB\-\-exist\fP
+when adding entry if it already exists, reset the timeout value
+to the specified one or to the default from the set definition
+.PP
+Use of -j SET requires that ipset kernel support is provided, which, for
+standard kernels, is the case since Linux 2.6.39.
.SS SNAT
This target is only valid in the
.B nat
mangled), and rules should cease being examined. It takes one type
of option:
.TP
-.BR "--to-source " "\fIipaddr\fP[-\fIipaddr\fP][:\fIport\fP-\fIport\fP]"
+\fB\-\-to\-source\fP [\fIipaddr\fP[\fB\-\fP\fIipaddr\fP]][\fB:\fP\fIport\fP[\fB\-\fP\fIport\fP]]
which can specify a single new source IP address, an inclusive range
of IP addresses, and optionally, a port range (which is only valid if
the rule also specifies
-.B "-p tcp"
+\fB\-p tcp\fP
or
-.BR "-p udp" ).
+\fB\-p udp\fP).
If no port range is specified, then source ports below 512 will be
mapped to other ports below 512: those between 512 and 1023 inclusive
will be mapped to ports below 1024, and other ports will be mapped to
1024 or above. Where possible, no port alteration will occur.
-.RS
-.PP
-You can add several --to-source options. If you specify more
-than one source address, either via an address range or multiple
---to-source options, a simple round-robin (one after another in
-cycle) takes place between these adresses.
+
+In Kernels up to 2.6.10, you can add several \-\-to\-source options. For those
+kernels, if you specify more than one source address, either via an address
+range or multiple \-\-to\-source options, a simple round-robin (one after another
+in cycle) takes place between these addresses.
+Later Kernels (>= 2.6.11-rc1) don't have the ability to NAT to multiple ranges
+anymore.
+.TP
+\fB\-\-random\fP
+If option
+\fB\-\-random\fP
+is used then port mapping will be randomized (kernel >= 2.6.21).
+.TP
+\fB\-\-persistent\fP
+Gives a client the same source-/destination-address for each connection.
+This supersedes the SAME target. Support for persistent mappings is available
+from 2.6.29-rc2.
.SS TCPMSS
This target allows to alter the MSS value of TCP SYN packets, to control
the maximum size for that connection (usually limiting it to your
-outgoing interface's MTU minus 40). Of course, it can only be used
+outgoing interface's MTU minus 40 for IPv4 or 60 for IPv6, respectively).
+Of course, it can only be used
in conjunction with
-.BR "-p tcp" .
-.br
+\fB\-p tcp\fP.
+.PP
This target is used to overcome criminally braindead ISPs or servers
-which block ICMP Fragmentation Needed packets. The symptoms of this
+which block "ICMP Fragmentation Needed" or "ICMPv6 Packet Too Big"
+packets. The symptoms of this
problem are that everything works fine from your Linux
firewall/router, but machines behind it can never exchange large
packets:
-.PD 0
-.RS 0.1i
-.TP 0.3i
-1)
+.IP 1. 4
Web browsers connect, then hang with no data received.
-.TP
-2)
+.IP 2. 4
Small mail works fine, but large emails hang.
-.TP
-3)
+.IP 3. 4
ssh works fine, but scp hangs after initial handshaking.
-.RE
-.PD
+.PP
Workaround: activate this option and add a rule to your firewall
configuration like:
-.nf
- iptables -A FORWARD -p tcp --tcp-flags SYN,RST SYN \\
- -j TCPMSS --clamp-mss-to-pmtu
-.fi
+.IP
+ iptables \-t mangle \-A FORWARD \-p tcp \-\-tcp\-flags SYN,RST SYN
+ \-j TCPMSS \-\-clamp\-mss\-to\-pmtu
+.TP
+\fB\-\-set\-mss\fP \fIvalue\fP
+Explicitly sets MSS option to specified value. If the MSS of the packet is
+already lower than \fIvalue\fP, it will \fBnot\fP be increased (from Linux
+2.6.25 onwards) to avoid more problems with hosts relying on a proper MSS.
+.TP
+\fB\-\-clamp\-mss\-to\-pmtu\fP
+Automatically clamp MSS value to (path_MTU \- 40 for IPv4; \-60 for IPv6).
+This may not function as desired where asymmetric routes with differing
+path MTU exist \(em the kernel uses the path MTU which it would use to send
+packets from itself to the source and destination IP addresses. Prior to
+Linux 2.6.25, only the path MTU to the destination IP address was
+considered by this option; subsequent kernels also consider the path MTU
+to the source IP address.
+.PP
+These options are mutually exclusive.
+.SS TCPOPTSTRIP
+This target will strip TCP options off a TCP packet. (It will actually replace
+them by NO-OPs.) As such, you will need to add the \fB\-p tcp\fP parameters.
+.TP
+\fB\-\-strip\-options\fP \fIoption\fP[\fB,\fP\fIoption\fP...]
+Strip the given option(s). The options may be specified by TCP option number or
+by symbolic name. The list of recognized options can be obtained by calling
+iptables with \fB\-j TCPOPTSTRIP \-h\fP.
+.SS TEE
+The \fBTEE\fP target will clone a packet and redirect this clone to another
+machine on the \fBlocal\fP network segment. In other words, the nexthop
+must be the target, or you will have to configure the nexthop to forward it
+further if so desired.
+.TP
+\fB\-\-gateway\fP \fIipaddr\fP
+Send the cloned packet to the host reachable at the given IP address.
+Use of 0.0.0.0 (for IPv4 packets) or :: (IPv6) is invalid.
+.PP
+To forward all incoming traffic on eth0 to an Network Layer logging box:
+.PP
+\-t mangle \-A PREROUTING \-i eth0 \-j TEE \-\-gateway 2001:db8::1
+.SS TOS
+This module sets the Type of Service field in the IPv4 header (including the
+"precedence" bits) or the Priority field in the IPv6 header. Note that TOS
+shares the same bits as DSCP and ECN. The TOS target is only valid in the
+\fBmangle\fP table.
+.TP
+\fB\-\-set\-tos\fP \fIvalue\fP[\fB/\fP\fImask\fP]
+Zeroes out the bits given by \fImask\fP (see NOTE below) and XORs \fIvalue\fP
+into the TOS/Priority field. If \fImask\fP is omitted, 0xFF is assumed.
+.TP
+\fB\-\-set\-tos\fP \fIsymbol\fP
+You can specify a symbolic name when using the TOS target for IPv4. It implies
+a mask of 0xFF (see NOTE below). The list of recognized TOS names can be
+obtained by calling iptables with \fB\-j TOS \-h\fP.
+.PP
+The following mnemonics are available:
.TP
-.BI "--set-mss " "value"
-Explicitly set MSS option to specified value.
+\fB\-\-and\-tos\fP \fIbits\fP
+Binary AND the TOS value with \fIbits\fP. (Mnemonic for \fB\-\-set\-tos
+0/\fP\fIinvbits\fP, where \fIinvbits\fP is the binary negation of \fIbits\fP.
+See NOTE below.)
.TP
-.B "--clamp-mss-to-pmtu"
-Automatically clamp MSS value to (path_MTU - 40).
+\fB\-\-or\-tos\fP \fIbits\fP
+Binary OR the TOS value with \fIbits\fP. (Mnemonic for \fB\-\-set\-tos\fP
+\fIbits\fP\fB/\fP\fIbits\fP. See NOTE below.)
.TP
-These options are mutually exclusive.
-.SS TOS
-This is used to set the 8-bit Type of Service field in the IP header.
-It is only valid in the
+\fB\-\-xor\-tos\fP \fIbits\fP
+Binary XOR the TOS value with \fIbits\fP. (Mnemonic for \fB\-\-set\-tos\fP
+\fIbits\fP\fB/0\fP. See NOTE below.)
+.PP
+NOTE: In Linux kernels up to and including 2.6.38, with the exception of
+longterm releases 2.6.32 (>=.42), 2.6.33 (>=.15), and 2.6.35 (>=.14), there is
+a bug whereby IPv6 TOS mangling does not behave as documented and differs from
+the IPv4 version. The TOS mask indicates the bits one wants to zero out, so it
+needs to be inverted before applying it to the original TOS field. However, the
+aformentioned kernels forgo the inversion which breaks --set-tos and its
+mnemonics.
+.SS TPROXY
+This target is only valid in the \fBmangle\fP table, in the \fBPREROUTING\fP
+chain and user-defined chains which are only called from this chain. It
+redirects the packet to a local socket without changing the packet header in
+any way. It can also change the mark value which can then be used in advanced
+routing rules.
+It takes three options:
+.TP
+\fB\-\-on\-port\fP \fIport\fP
+This specifies a destination port to use. It is a required option, 0 means the
+new destination port is the same as the original. This is only valid if the
+rule also specifies \fB\-p tcp\fP or \fB\-p udp\fP.
+.TP
+\fB\-\-on\-ip\fP \fIaddress\fP
+This specifies a destination address to use. By default the address is the IP
+address of the incoming interface. This is only valid if the rule also
+specifies \fB\-p tcp\fP or \fB\-p udp\fP.
+.TP
+\fB\-\-tproxy\-mark\fP \fIvalue\fP[\fB/\fP\fImask\fP]
+Marks packets with the given value/mask. The fwmark value set here can be used
+by advanced routing. (Required for transparent proxying to work: otherwise
+these packets will get forwarded, which is probably not what you want.)
+.SS TRACE
+This target marks packets so that the kernel will log every rule which match
+the packets as those traverse the tables, chains, rules.
+.PP
+A logging backend, such as ip(6)t_LOG or nfnetlink_log, must be loaded for this
+to be visible.
+The packets are logged with the string prefix:
+"TRACE: tablename:chainname:type:rulenum " where type can be "rule" for
+plain rule, "return" for implicit rule at the end of a user defined chain
+and "policy" for the policy of the built in chains.
+.br
+It can only be used in the
+.BR raw
+table.
+.SS TTL
+This is used to modify the IPv4 TTL header field. The TTL field determines
+how many hops (routers) a packet can traverse until it's time to live is
+exceeded.
+.PP
+Setting or incrementing the TTL field can potentially be very dangerous,
+so it should be avoided at any cost. This target is only valid in
.B mangle
table.
+.PP
+.B Don't ever set or increment the value on packets that leave your local network!
.TP
-.BI "--set-tos " "tos"
-You can use a numeric TOS values, or use
-.nf
- iptables -j TOS -h
-.fi
-to see the list of valid TOS names.
+\fB\-\-ttl\-set\fP \fIvalue\fP
+Set the TTL value to `value'.
+.TP
+\fB\-\-ttl\-dec\fP \fIvalue\fP
+Decrement the TTL value `value' times.
+.TP
+\fB\-\-ttl\-inc\fP \fIvalue\fP
+Increment the TTL value `value' times.
.SS ULOG
This target provides userspace logging of matching packets. When this
target is set for a rule, the Linux kernel will multicast this packet
Like LOG, this is a "non-terminating target", i.e. rule traversal
continues at the next rule.
.TP
-.BI "--ulog-nlgroup " "nlgroup"
+\fB\-\-ulog\-nlgroup\fP \fInlgroup\fP
This specifies the netlink group (1-32) to which the packet is sent.
Default value is 1.
.TP
-.BI "--ulog-prefix " "prefix"
+\fB\-\-ulog\-prefix\fP \fIprefix\fP
Prefix log messages with the specified prefix; up to 32 characters
long, and useful for distinguishing messages in the logs.
.TP
-.BI "--ulog-cprange " "size"
+\fB\-\-ulog\-cprange\fP \fIsize\fP
Number of bytes to be copied to userspace. A value of 0 always copies
the entire packet, regardless of its size. Default is 0.
.TP
-.BI "--ulog-qthreshold " "size"
+\fB\-\-ulog\-qthreshold\fP \fIsize\fP
Number of packet to queue inside kernel. Setting this value to, e.g. 10
accumulates ten packets inside the kernel and transmits them as one
netlink multipart message to userspace. Default is 1 (for backwards
other errors cause an exit code of 1.
.SH BUGS
Bugs? What's this? ;-)
-Well... the counters are not reliable on sparc64.
+Well, you might want to have a look at http://bugzilla.netfilter.org/
.SH COMPATIBILITY WITH IPCHAINS
-This
-.B iptables
+This \fBiptables\fP
is very similar to ipchains by Rusty Russell. The main difference is
-that the chains
-.B INPUT
-and
-.B OUTPUT
+that the chains \fBINPUT\fP and \fBOUTPUT\fP
are only traversed for packets coming into the local host and
originating from the local host respectively. Hence every packet only
passes through one of the three chains (except loopback traffic, which
involves both INPUT and OUTPUT chains); previously a forwarded packet
would pass through all three.
.PP
-The other main difference is that
-.B -i
-refers to the input interface;
-.B -o
-refers to the output interface, and both are available for packets
-entering the
-.B FORWARD
-chain.
+The other main difference is that \fB\-i\fP refers to the input interface;
+\fB\-o\fP refers to the output interface, and both are available for packets
+entering the \fBFORWARD\fP chain.
.PP
-The various forms of NAT have been separated out;
-.B iptables
+The various forms of NAT have been separated out; \fBiptables\fP
is a pure packet filter when using the default `filter' table, with
optional extension modules. This should simplify much of the previous
confusion over the combination of IP masquerading and packet filtering
seen previously. So the following options are handled differently:
.nf
- -j MASQ
- -M -S
- -M -L
+ \-j MASQ
+ \-M \-S
+ \-M \-L
.fi
There are several other changes in iptables.
.SH SEE ALSO
-.BR iptables-save (8),
-.BR iptables-restore (8),
-.BR ip6tables (8),
-.BR ip6tables-save (8),
-.BR ip6tables-restore (8).
-.P
+\fBiptables\-save\fP(8),
+\fBiptables\-restore\fP(8),
+\fBip6tables\fP(8),
+\fBip6tables\-save\fP(8),
+\fBip6tables\-restore\fP(8),
+\fBlibipq\fP(3).
+.PP
The packet-filtering-HOWTO details iptables usage for
packet filtering, the NAT-HOWTO details NAT,
the netfilter-extensions-HOWTO details the extensions that are
See
.BR "http://www.netfilter.org/" .
.SH AUTHORS
-Rusty Russell wrote iptables, in early consultation with Michael
+Rusty Russell originally wrote iptables, in early consultation with Michael
Neuling.
.PP
Marc Boucher made Rusty abandon ipnatctl by lobbying for a generic packet
.PP
Jozsef Kadlecsik wrote the REJECT target.
.PP
-Harald Welte wrote the ULOG target, TTL, DSCP, ECN matches and targets.
+Harald Welte wrote the ULOG and NFQUEUE target, the new libiptc, as well as the TTL, DSCP, ECN matches and targets.
.PP
-The Netfilter Core Team is: Marc Boucher, Martin Josefsson, Jozsef Kadlecsik,
-James Morris, Harald Welte and Rusty Russell.
+The Netfilter Core Team is: Marc Boucher, Martin Josefsson, Yasuyuki Kozakai,
+Jozsef Kadlecsik, Patrick McHardy, James Morris, Pablo Neira Ayuso,
+Harald Welte and Rusty Russell.
.PP
-Man page written by Herve Eychenne <rv@wallfire.org>.
+Man page originally written by Herve Eychenne <rv@wallfire.org>.
.\" .. and did I mention that we are incredibly cool people?
.\" .. sexy, too ..
.\" .. witty, charming, powerful ..
.\" .. and most of all, modest ..
+.SH VERSION
+.PP
+This manual page applies to iptables @PACKAGE_VERSION@.
-×:iptables:1.2.9:2000/11/18:ipq_create_handle:3:::::
-※:iptables:1.2.9:2000/11/18:ipq_destroy_handle:3:ipq_create_handle:3:
-×:iptables:1.2.9:2000/11/18:ipq_errstr:3:::::
-※:iptables:1.2.9:2000/11/18:ipq_get_msgerr:3:ipq_message_type:3:
-※:iptables:1.2.9:2000/11/18:ipq_get_packet:3:ipq_message_type:3:
-×:iptables:1.2.9:2000/11/18:ipq_message_type:3:::::
-※:iptables:1.2.9:2000/11/18:ipq_perror:3:ipq_errstr:3:
-×:iptables:1.2.9:2000/11/18:ipq_read:3:::::
-×:iptables:1.2.9:2000/11/18:ipq_set_mode:3:::::
-×:iptables:1.2.9:2000/11/18:ipq_set_verdict:3:::::
-●:iptables:1.2.9:2000/11/18:libipq:3:2003/06/06::szuka@isp.co.jp:Susumu ISHIZUKA:
-○:iptables:1.2.9:2002/03/09:ip6tables:8:2004/03/12::ysato444@yahoo.co.jp:Yuichi SATO:
-○:iptables:1.2.9:2002/01/30:ip6tables-restore:8:2003/05/13::ysato444@yahoo.co.jp:Yuichi SATO:
-○:iptables:1.2.9:2002/01/30:ip6tables-save:8:2003/05/13::ysato444@yahoo.co.jp:Yuichi SATO:
-○:iptables:1.2.9:2002/03/09:iptables:8:2004/03/12::ysato444@yahoo.co.jp:Yuichi SATO:
-○:iptables:1.2.9:2001/03/16:iptables-restore:8:2001/05/15::ysato@h4.dion.ne.jp:Yuichi SATO:
-○:iptables:1.2.9:2001/03/16:iptables-save:8:2001/05/15::ysato@h4.dion.ne.jp:Yuichi SATO:
+×:iptables:1.4.13:2012/03/27:iptables-xml:1:::::
+×:iptables:1.4.13:2012/03/27:ipq_create_handle:3:::::
+※:iptables:1.4.13:2012/03/27:ipq_destroy_handle:3:ipq_create_handle:3:
+×:iptables:1.4.13:2012/03/27:ipq_errstr:3:::::
+※:iptables:1.4.13:2012/03/27:ipq_get_msgerr:3:ipq_message_type:3:
+※:iptables:1.4.13:2012/03/27:ipq_get_packet:3:ipq_message_type:3:
+×:iptables:1.4.13:2012/03/27:ipq_message_type:3:::::
+※:iptables:1.4.13:2012/03/27:ipq_perror:3:ipq_errstr:3:
+×:iptables:1.4.13:2012/03/27:ipq_read:3:::::
+×:iptables:1.4.13:2012/03/27:ipq_set_mode:3:::::
+×:iptables:1.4.13:2012/03/27:ipq_set_verdict:3:::::
+:iptables:1.4.13:2012/03/27:libipq:3:::::
+☆:iptables:1.4.13:2012/03/27:ip6tables:8:2004/03/12::ysato444@yahoo.co.jp:Yuichi SATO:
+☆:iptables:1.2.9=>1.4.13:2012/03/27:ip6tables-restore:8:2003/05/13::ysato444@yahoo.co.jp:Yuichi SATO:
+☆:iptables:1.2.9=>1.4.13:2012/03/27:ip6tables-save:8:2003/05/13::ysato444@yahoo.co.jp:Yuichi SATO:
+☆:iptables:1.4.13:2012/03/27:iptables:8:2004/03/12::ysato444@yahoo.co.jp:Yuichi SATO:
+×:iptables:1.4.13:2012/03/27:iptables-apply:8:::::
+☆:iptables:1.2.9=>1.4.13:2012/03/27:iptables-restore:8:2001/05/15::ysato@h4.dion.ne.jp:Yuichi SATO:
+☆:iptables:1.2.9=>1.4.13:2012/03/27:iptables-save:8:2001/05/15::ysato@h4.dion.ne.jp:Yuichi SATO:
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