.TH IPSEC.CONF 5 "26 Nov 2001"
.\" RCSID $Id: ipsec.conf.5,v 1.79 2001/11/26 15:51:24 henry Exp $
.SH NAME
ipsec.conf \- IPsec configuration and connections
.SH DESCRIPTION
The
.I ipsec.conf
file
specifies most configuration and control information for the
FreeS/WAN IPsec subsystem.
(The major exception is secrets for authentication;
see
.IR ipsec.secrets (5).)
Its contents are not security-sensitive
.I unless
manual keying is being done for more than just testing,
in which case the encryption/authentication keys in the
descriptions for the manually-keyed connections are very sensitive
(and those connection descriptions
are probably best kept in a separate file,
via the include facility described below).
.PP
The file is a text file, consisting of one or more
.IR sections .
White space followed by
.B #
followed by anything to the end of the line
is a comment and is ignored,
as are empty lines which are not within a section.
.PP
A line which contains
.B include
and a file name, separated by white space,
is replaced by the contents of that file,
preceded and followed by empty lines.
If the file name is not a full pathname,
it is considered to be relative to the directory containing the
including file.
Such inclusions can be nested.
Only a single filename may be supplied, and it may not contain white space,
but it may include shell wildcards (see
.IR sh (1));
for example:
.PP
.B include
.B "ipsec.*.conf"
.PP
The intention of the include facility is mostly to permit keeping
information on connections, or sets of connections,
separate from the main configuration file.
This permits such connection descriptions to be changed,
copied to the other security gateways involved, etc.,
without having to constantly extract them from the configuration
file and then insert them back into it.
Note also the
.B also
parameter (described below) which permits splitting a single logical section
(e.g. a connection description) into several actual sections.
.PP
A section
begins with a line of the form:
.PP
.I type
.I name
.PP
where
.I type
indicates what type of section follows, and
.I name
is an arbitrary name which distinguishes the section from others
of the same type.
(Names must start with a letter and may contain only
letters, digits, periods, underscores, and hyphens.)
All subsequent non-empty lines
which begin with white space are part of the section;
comments within a section must begin with white space too.
There may be only one section of a given type with a given name.
.PP
Lines within the section are generally of the form
.PP
\ \ \ \ \ \fIparameter\fB=\fIvalue\fR
.PP
(note the mandatory preceding white space).
There can be white space on either side of the
.BR = .
Parameter names follow the same syntax as section names,
and are specific to a section type.
Unless otherwise explicitly specified,
no parameter name may appear more than once in a section.
.PP
An empty
.I value
stands for the system default value (if any) of the parameter,
i.e. it is roughly equivalent to omitting the parameter line entirely.
A
.I value
may contain white space only if the entire
.I value
is enclosed in double quotes (\fB"\fR);
a
.I value
cannot itself contain a double quote,
nor may it be continued across more than one line.
.PP
Numeric values are specified to be either an ``integer''
(a sequence of digits) or a ``decimal number''
(sequence of digits optionally followed by `.' and another sequence of digits).
.PP
There is currently one parameter which is available in any type of
section:
.TP
.B also
the value is a section name;
the parameters of that section are appended to this section,
as if they had been written as part of it.
The specified section must exist, must follow the current one,
and must have the same section type.
(Nesting is permitted,
and there may be more than one
.B also
in a single section,
although it is forbidden to append the same section more than once.)
This allows, for example, keeping the encryption keys
for a connection in a separate file
from the rest of the description, by using both an
.B also
parameter and an
.B include
line.
(Caution, see BUGS below for some restrictions.)
.PP
Parameter names beginning with
.B x-
(or
.BR X- ,
or
.BR x_ ,
or
.BR X_ )
are reserved for user extensions and will never be assigned meanings
by IPsec.
Parameters with such names must still observe the syntax rules
(limits on characters used in the name;
no white space in a non-quoted value;
no newlines or double quotes within the value).
All other as-yet-unused parameter names are reserved for future IPsec
improvements.
.PP
A section with name
.B %default
specifies defaults for sections of the same type.
For each parameter in it,
any section of that type which does not have a parameter of the same name
gets a copy of the one from the
.B %default
section.
There may be multiple
.B %default
sections of a given type,
but only one default may be supplied for any specific parameter name,
and all
.B %default
sections of a given type must precede all non-\c
.B %default
sections of that type.
.B %default
sections may not contain
.B also
parameters.
.PP
Currently there are two types of section:
a
.B config
section specifies general configuration information for IPsec,
while a
.B conn
section specifies an IPsec connection.
.SH "CONN SECTIONS"
A
.B conn
section contains a
.IR "connection specification" ,
defining a network connection to be made using IPsec.
The name given is arbitrary, and is used to identify the connection to
.IR ipsec_auto (8)
and
.IR ipsec_manual (8).
Here's a simple example:
.PP
.ne 10
.nf
.ft B
.ta 1c
conn snt
	left=10.11.11.1
	leftsubnet=10.0.1.0/24
	leftnexthop=172.16.55.66
	right=192.168.22.1
	rightsubnet=10.0.2.0/24
	rightnexthop=172.16.88.99
	keyingtries=0                # be very persistent
.ft
.fi
.PP
A note on terminology...
In automatic keying, there are two kinds of communications going on:
transmission of user IP packets, and gateway-to-gateway negotiations for
keying, rekeying, and general control.
The data path (a set of ``IPsec SAs'') used for user packets is herein
referred to as the ``connection'';
the path used for negotiations (built with ``ISAKMP SAs'') is referred to as
the ``keying channel''.
.PP
To avoid trivial editing of the configuration file to suit it to each system
involved in a connection,
connection specifications are written in terms of
.I left
and
.I right
participants,
rather than in terms of local and remote.
Which participant is considered
.I left
or
.I right
is arbitrary;
IPsec figures out which one it is being run on based on internal information.
This permits using identical connection specifications on both ends.
.PP
Many of the parameters relate to one participant or the other;
only the ones for
.I left
are listed here, but every parameter whose name begins with
.B left
has a
.B right
counterpart,
whose description is the same but with
.B left
and
.B right
reversed.
.PP
Parameters are optional unless marked ``(required)'';
a parameter required for manual keying need not be included for
a connection which will use only automatic keying, and vice versa.
.SS "CONN PARAMETERS:  GENERAL"
The following parameters are relevant to both automatic and manual keying.
Unless otherwise noted,
for a connection to work,
in general it is necessary for the two ends to agree exactly
on the values of these parameters.
.TP 14
.B type
the type of the connection; currently the accepted values
are
.B tunnel
(the default)
signifying a host-to-host, host-to-subnet, or subnet-to-subnet tunnel;
.BR transport ,
signifying host-to-host transport mode;
and
.BR passthrough
(supported only for manual keying),
signifying that no IPsec processing should be done at all
.TP
.B left
(required)
the IP address of the left participant's public-network interface,
in any form accepted by
.IR ipsec_ttoaddr (3).
If it is the magic value
.BR %defaultroute ,
and
.B interfaces=%defaultroute
is used in the
.B config
.B setup
section,
.B left
will be filled in automatically with the local address
of the default-route interface (as determined at IPsec startup time);
this also overrides any value supplied for
.BR leftnexthop .
(Either
.B left
or
.B right
may be
.BR %defaultroute ,
but not both.)
The magic value
.B %any
signifies an address to be filled in (by automatic keying) during
negotiation;
the magic value
.B %opportunistic
signifies that both
.B left
and
.B leftnexthop
are to be filled in (by automatic keying) from DNS data for
.BR left 's
client.
.TP
.B leftsubnet
private subnet behind the left participant, expressed as
\fInetwork\fB/\fInetmask\fR
(actually, any form acceptable to
.IR ipsec_ttosubnet (3));
if omitted, essentially assumed to be \fIleft\fB/32\fR,
signifying that the left end of the connection goes to the left participant only
.TP
.B leftnexthop
next-hop gateway IP address for the left participant's connection
to the public network;
defaults to
.B %direct
(meaning
.IR right ).
If the value is to be overridden by the
.B left=%defaultroute
method (see above),
an explicit value must
.I not
be given.
If that method is not being used,
but
.B leftnexthop
is
.BR %defaultroute ,
and
.B interfaces=%defaultroute
is used in the
.B config
.B setup
section,
the next-hop gateway address of the default-route interface
will be used.
The magic value
.B %direct
signifies a value to be filled in (by automatic keying)
with the peer's address.
Relevant only locally, other end need not agree on it.
.TP
.B leftupdown
what ``updown'' script to run to adjust routing and/or firewalling
when the status of the connection
changes (default
.BR "ipsec _updown" ).
May include positional parameters separated by white space
(although this requires enclosing the whole string in quotes);
including shell metacharacters is unwise.
See
.IR ipsec_pluto (8)
for details.
Relevant only locally, other end need not agree on it.
.TP
.B leftfirewall
whether the left participant is doing forwarding-firewalling
(including masquerading) for traffic from \fIleftsubnet\fR,
which should be turned off (for traffic to the other subnet)
once the connection is established;
acceptable values are
.B yes
and (the default)
.BR no .
May not be used in the same connection description with
.BR leftupdown .
Implemented as a parameter to the default
.I updown
script.
See notes below.
Relevant only locally, other end need not agree on it.
.PP
If one or both security gateways are doing forwarding firewalling
(possibly including masquerading),
and this is specified using the firewall parameters,
tunnels established with IPsec are exempted from it
so that packets can flow unchanged through the tunnels.
(This means that all subnets connected in this manner must have
distinct, non-overlapping subnet address blocks.)
This is done by the default
.I updown
script (see
.IR ipsec_pluto (8)).
.PP
The implementation of this makes certain assumptions about firewall setup,
notably the use of the old
.I ipfwadm
interface to the firewall.
In situations calling for more control,
it may be preferable for the user to supply his own
.I updown
script,
which makes the appropriate adjustments for his system.
.SS "CONN PARAMETERS:  AUTOMATIC KEYING"
The following parameters are relevant only to automatic keying,
and are ignored in manual keying.
Unless otherwise noted,
for a connection to work,
in general it is necessary for the two ends to agree exactly
on the values of these parameters.
.TP 14
.B keyexchange
method of key exchange;
the default and currently the only accepted value is
.B ike
.TP
.B auto
what operation, if any, should be done automatically at IPsec startup;
currently-accepted values are
.B add
(signifying an
.B ipsec auto
.BR \-\-add ),
.B route
(signifying that plus an
.B ipsec auto
.BR \-\-route ),
.B start
(signifying that plus an
.B ipsec auto
.BR \-\-up ),
and
.B ignore
(also the default) (signifying no automatic startup operation).
This parameter is ignored unless the
.B plutoload
or
.B plutostart
configuration parameter is set suitably; see the
.B config
.B setup
discussion below.
Relevant only locally, other end need not agree on it
(but in general, for an intended-to-be-permanent connection,
both ends should use
.B auto=start
to ensure that any reboot causes immediate renegotiation).
.TP
.B auth
whether authentication should be done as part of
ESP encryption, or separately using the AH protocol;
acceptable values are
.B esp
(the default) and
.BR ah .
.TP
.B authby
how the two security gateways should authenticate each other;
acceptable values are
.B secret
for shared secrets (the default) and
.B rsasig
for RSA digital signatures
.TP
.B leftid
how
the left participant
should be identified for authentication;
defaults to
.BR left .
Can be an IP address (in any
.IR ipsec_ttoaddr (3)
syntax)
or a fully-qualified domain name preceded by
.B @
(which is used as a literal string and not resolved).
.TP
.B leftrsasigkey
the left participant's
public key for RSA signature authentication,
in RFC 2537 format using
.IR ipsec_ttodata (3)
encoding;
the magic value
.B %dns
means to fetch it from DNS (at the time
the connection description is read from
.IR ipsec.conf )
instead.
The identity used for the left participant
must be a specific host, not
.B %any
or another magic value.
.B Caution:
if two connection descriptions
specify different public keys for the same
.BR leftid ,
confusion and madness will ensue.
.TP
.B pfs
whether Perfect Forward Secrecy of keys is desired on the connection's
keying channel
(with PFS, penetration of the key-exchange protocol
does not compromise keys negotiated earlier);
acceptable values are
.B yes
(the default)
and
.BR no .
.TP
.B keylife
how long a particular instance of a connection
(a set of encryption/authentication keys for user packets) should last,
from successful negotiation to expiry;
acceptable values are an integer optionally followed by
.BR s
(a time in seconds)
or a decimal number followed by
.BR m ,
.BR h ,
or
.B d
(a time
in minutes, hours, or days respectively)
(default
.BR 8.0h ,
maximum
.BR 24h ).
Normally, the connection is renegotiated (via the keying channel)
before it expires.
The two ends need not exactly agree on
.BR keylife ,
although if they do not,
there will be some clutter of superseded connections on the end
which thinks the lifetime is longer.
.TP
.B rekey
whether a connection should be renegotiated when it is about to expire;
acceptable values are
.B yes
(the default)
and
.BR no .
The two ends need not agree,
but while a value of
.B no
prevents Pluto from requesting renegotiation,
it does not prevent responding to renegotiation requested from the other end,
so
.B no
will be largely ineffective unless both ends agree on it.
.TP
.B rekeymargin
how long before connection expiry or keying-channel expiry
should attempts to
negotiate a replacement
begin; acceptable values as for
.B keylife
(default
.BR 9m ).
Relevant only locally, other end need not agree on it.
.TP
.B rekeyfuzz
maximum percentage by which
.B rekeymargin
should be randomly increased to randomize rekeying intervals
(important for hosts with many connections);
acceptable values are an integer,
which may exceed 100,
followed by a `%'
(default set by
.IR ipsec_pluto (8),
currently
.BR 100% ).
The value of
.BR rekeymargin ,
after this random increase,
must not exceed
.BR keylife .
The value
.B 0%
will suppress time randomization.
Relevant only locally, other end need not agree on it.
.TP
.B keyingtries
how many attempts (an integer) should be made to
negotiate a connection, or a replacement for one, before giving up
(default
.BR 3 );
the value
.B 0
means ``never give up''
Relevant only locally, other end need not agree on it.
.TP
.B ikelifetime
how long the keying channel of a connection (buzzphrase:  ``ISAKMP SA'')
should last before being renegotiated;
acceptable values as for
.B keylife
(default set by
.IR ipsec_pluto (8),
currently
.BR 1h ,
maximum
.BR 8h ).
The two-ends-disagree case is similar to that of
.BR keylife .
.TP
.B compress
whether IPComp compression of content is desired on the connection
(link-level compression does not work on encrypted data,
so to be effective, compression must be done \fIbefore\fR encryption);
acceptable values are
.B yes
and
.B no
(the default).
The two ends need not agree.
A value of
.B no
is absolute:
IPsec will neither propose nor accept compression.
A value of
.B yes
causes IPsec to propose both compressed and uncompressed,
and prefer compressed.
.TP
.B disablearrivalcheck
whether KLIPS's normal tunnel-exit check
(that a packet emerging from a tunnel has plausible addresses in its header)
should be disabled;
acceptable values are
.B yes
(the backward-compatible default)
and
.BR no .
Relevant only locally, other end need not agree on it.
.SS "CONN PARAMETERS:  MANUAL KEYING"
The following parameters are relevant only to manual keying,
and are ignored in automatic keying.
Unless otherwise noted,
for a connection to work,
in general it is necessary for the two ends to agree exactly
on the values of these parameters.
A manually-keyed
connection must specify at least one of AH or ESP.
.TP 14
.B spi
(this or
.B spibase
required for manual keying)
the SPI number to be used for the connection (see
.IR ipsec_manual (8));
must be of the form \fB0x\fIhex\fB\fR,
where
.I hex
is one or more hexadecimal digits
(note, it will generally be necessary to make
.I spi
at least
.B 0x100
to be acceptable to KLIPS,
and use of SPIs in the range
.BR 0x100 - 0xfff
is recommended)
.TP 14
.B spibase
(this or
.B spi
required for manual keying)
the base number for the SPIs to be used for the connection (see
.IR ipsec_manual (8));
must be of the form \fB0x\fIhex\fB0\fR,
where
.I hex
is one or more hexadecimal digits
(note, it will generally be necessary to make
.I spibase
at least
.B 0x100
for the resulting SPIs
to be acceptable to KLIPS,
and use of numbers in the range
.BR 0x100 - 0xff0
is recommended)
.TP
.B esp
ESP encryption/authentication algorithm to be used
for the connection, e.g.
.B 3des-md5-96
(must be suitable as a value of
.IR ipsec_spi (8)'s
.B \-\-esp
option);
default is not to use ESP
.TP
.B espenckey
ESP encryption key
(must be suitable as a value of
.IR ipsec_spi (8)'s
.B \-\-enckey
option)
(may be specified separately for each direction using
.B leftespenckey
(leftward SA)
and
.B rightespenckey
parameters)
.TP
.B espauthkey
ESP authentication key
(must be suitable as a value of
.IR ipsec_spi (8)'s
.B \-\-authkey
option)
(may be specified separately for each direction using
.B leftespauthkey
(leftward SA)
and
.B rightespauthkey
parameters)
.TP
.B espreplay_window
ESP replay-window setting,
an integer from
.B 0
(the
.IR ipsec_manual
default, which turns off replay protection) to
.BR 64 ;
relevant only if ESP authentication is being used
.TP
.B leftespspi
SPI to be used for the leftward ESP SA, overriding
automatic assignment using
.B spi
or
.BR spibase ;
typically a hexadecimal number beginning with
.B 0x
.TP
.B ah
AH authentication algorithm to be used
for the connection, e.g.
.B hmac-md5-96
(must be suitable as a value of
.IR ipsec_spi (8)'s
.B \-\-ah
option);
default is not to use AH
.TP
.B ahkey
(required if
.B ah
is present) AH authentication key
(must be suitable as a value of
.IR ipsec_spi (8)'s
.B \-\-authkey
option)
(may be specified separately for each direction using
.B leftahkey
(leftward SA)
and
.B rightahkey
parameters)
.TP
.B ahreplay_window
AH replay-window setting,
an integer from
.B 0
(the
.I ipsec_manual
default, which turns off replay protection) to
.B 64
.TP
.B leftahspi
SPI to be used for the leftward AH SA, overriding
automatic assignment using
.B spi
or
.BR spibase ;
typically a hexadecimal number beginning with
.B 0x
.SH "CONFIG SECTIONS"
At present, the only
.B config
section known to the IPsec software is the one named
.BR setup ,
which contains information used when the software is being started
(see
.IR ipsec_setup (8)).
Here's an example:
.PP
.ne 8
.nf
.ft B
.ta 1c
config setup
	interfaces="ipsec0=eth1 ipsec1=ppp0"
	klipsdebug=none
	plutodebug=all
	manualstart=
	plutoload="snta sntb sntc sntd"
	plutostart=
.ft
.fi
.PP
Parameters are optional unless marked ``(required)''.
The currently-accepted
.I parameter
names in a
.B config
.B setup
section are:
.TP 14
.B interfaces
(required)
virtual and physical interfaces for IPsec to use:
a single
\fIvirtual\fB=\fIphysical\fR pair, a (quoted!) list of pairs separated
by white space,
or
.BR %defaultroute ,
which means to find the interface \fId\fR that the default route points to,
and then act as if the value was ``\fBipsec0=\fId\fR''.
(Also, in the
.B %defaultroute
case,
information about the default route and its interface is noted for
use by
.IR ipsec_manual (8)
and
.IR ipsec_auto (8).)
.TP
.B forwardcontrol
whether
.I setup
should turn IP forwarding on
(if it's not already on) as IPsec is started,
and turn it off again (if it was off) as IPsec is stopped;
acceptable values are
.B yes
and (the default)
.BR no .
For this to have full effect, forwarding must be
disabled before the hardware interfaces are brought
up (e.g.,
.B "net.ipv4.ip_forward\ =\ 0"
in Red Hat 6.x
.IR /etc/sysctl.conf ),
because IPsec doesn't get control early enough to do that.
.TP
.B syslog
the
.IR syslog (2)
``facility'' name and priority to use for
startup/shutdown log messages,
default
.BR daemon.error .
.TP
.B klipsdebug
how much KLIPS debugging output should be logged.
An empty value,
or the magic value
.BR none ,
means no debugging output (the default).
The magic value
.B all
means full output.
Otherwise only the specified types of output
(a quoted list, names separated by white space) are enabled;
for details on available debugging types, see
.IR ipsec_klipsdebug (8).
.TP
.B plutodebug
how much Pluto debugging output should be logged.
An empty value,
or the magic value
.BR none ,
means no debugging output (the default).
The magic value
.B all
means full output.
Otherwise only the specified types of output
(a quoted list, names without the
.B \-\-debug\-
prefix,
separated by white space) are enabled;
for details on available debugging types, see
.IR ipsec_pluto (8).
.TP
.B dumpdir
in what directory should things started by
.I setup
(notably the Pluto daemon) be allowed to
dump core?
The empty value (the default) means they are not
allowed to.
.TP
.B dump
obsolete variant of
.BR dumpdir .
.B dump=no
is synonymous with
.B dumpdir=
and
.B dump=yes
is synonymous with
.BR dump=/var/tmp .
.TP
.B manualstart
which manually-keyed connections to set up at startup
(empty, a name, or a quoted list of names separated by white space);
see
.IR ipsec_manual (8).
Default is none.
.TP
.B pluto
whether to start Pluto or not;
Values are
.B yes
(the default)
or
.B no
(useful only in special circumstances).
.TP
.B plutoload
which connections (by name) to load
into Pluto's internal database at startup
(empty, a name, or a quoted list of names separated by white space);
see
.IR ipsec_auto (8)
for details.
Default is none.
If the special value
.B %search
is used, all connections with
.BR auto=add ,
.BR auto=route ,
or
.B auto=start
are loaded.
.TP
.B plutostart
which connections (by name) to attempt to negotiate
at startup (empty, a name, or a quoted
list of names separated by white space);
any such names which do not appear in
.B plutoload
are implicitly added to it.
Default is none.
If the special value
.B %search
is used, all connections with
.B auto=route
or
.B auto=start
are routed,
and all connections with
.B auto=start
are started.
.TP
.B plutowait
should Pluto wait for each
.B plutostart
negotiation attempt to
finish before proceeding with the next?
Values are
.B yes
(the default)
or
.BR no .
.TP
.B plutobackgroundload
obsolete parameter, ignored, nominally specifying whether
loading and starting of connections should be spun off as a background
process to avoid startup delays.
This is now always done.
Values were
.B yes
or
.BR no
(the default).
.TP
.B prepluto
shell command to run before starting Pluto
(e.g., to decrypt an encrypted copy of the
.I ipsec.secrets
file).
It's run in a very simple way;
complexities like I/O redirection are best hidden within a script.
Any output is redirected for logging,
so running interactive commands is difficult unless they use
.I /dev/tty
or equivalent for their interaction.
Default is none.
.TP
.B postpluto
shell command to run after starting Pluto
(e.g., to remove a decrypted copy of the
.I ipsec.secrets
file).
It's run in a very simple way;
complexities like I/O redirection are best hidden within a script.
Any output is redirected for logging,
so running interactive commands is difficult unless they use
.I /dev/tty
or equivalent for their interaction.
Default is none.
.TP
.B fragicmp
whether a tunnel's need to fragment a packet should be reported
back with an ICMP message,
in an attempt to make the sender lower his PMTU estimate;
acceptable values are
.B yes
(the default)
and
.BR no .
.TP
.B packetdefault
what should be done with
a packet which reaches KLIPS (via a route into a virtual interface)
but does not match any eroute;
acceptable values are
.B pass
(\fIinsecure unless you really know what you're doing!!!\fR),
.B drop
(the default),
and
.B reject
(currently same as
.BR drop ,
but eventually it will send an ICMP notification back
to the sender).
.TP
.B no_eroute_pass
obsolete parameter similar to
.B packetdefault
but with more limited functionality;
ignored if
.B packetdefault
is set;
acceptable values are
.B yes
(synonymous with
.BR packetdefault=pass )
and
.B no
(synonymous with
.BR packetdefault=drop )
(the default).
.TP
.B hidetos
whether a tunnel packet's TOS field should be set to
.B 0
rather than copied from the user packet inside;
acceptable values are
.B yes
(the default)
and
.BR no .
.TP
.B uniqueids
whether a particular participant ID should be kept unique,
with any new (automatically keyed)
connection using an ID from a different IP address
deemed to replace all old ones using that ID;
acceptable values are
.B yes
and
.B no
(the default).
.TP
.B overridemtu
value that the MTU of the ipsec\fIn\fR interface(s) should be set to,
overriding IPsec's (large) default.
This parameter is needed only in special situations.
.SH "RECOMMENDED CONFIGURATION"
Certain parameters are now strongly-recommended defaults,
but cannot (yet) be made system defaults due to backward compatibility.
They \fIare\fR supplied as ``boilerplate'' in the sample
.I ipsec.conf
file which is put in place as part of a new FreeS/WAN install.
.PP
Recommended
.B "config setup"
parameters are:
.TP
.B plutoload=%search
.TP
.B plutostart=%search
In practice, it is preferable to use the
.B auto
parameter to control whether a particular
connection is added or started automatically.
.TP
.B uniqueids=yes
Participant IDs normally \fIare\fR unique,
so a new (automatically-keyed) connection using the same ID is
almost invariably intended to replace an old one.
.PP
Recommended
.B conn
parameters (mostly for automatic keying, as manual keying seldom sees
much use) are:
.TP
.B keyingtries=0
Unlimited retries are normally appropriate for VPN connections.
Finite values may be needed for Road Warrior and other more-ephemeral
applications,
but the fixed small default is pretty much useless.
.TP
.B disablearrivalcheck=no
Tunnel-exit checks improve security and do not break any normal configuration.
.TP
.B authby=rsasig
Digital signatures are superior in every way to shared secrets.
.TP
.B leftrsasigkey=%dns
.TP
.B rightrsasigkey=%dns
Fetching public keys from DNS is generally more convenient
than having to preconfigure them in configuration files.
.SH FILES
/etc/ipsec.conf
.SH SEE ALSO
ipsec(8), ipsec_ttoaddr(8), ipsec_auto(8), ipsec_manual(8), ipsec_rsasigkey(8)
.SH HISTORY
Designed for the FreeS/WAN project
<http://www.freeswan.org>
by Henry Spencer.
.SH BUGS
Including attributes of the keying channel
(authentication methods,
.BR ikelifetime ,
etc.)
as an attribute of a connection,
rather than of a participant pair, is dubious and incurs limitations.
.PP
In general, the defaults often were chosen for backward compatibility
and are less than ideal.
Notably, the
.B keyingtries
default should be
.BR 0 .
.PP
.IR Ipsec_manual
is not nearly as generous about the syntax of subnets,
addresses, etc. as the usual FreeS/WAN user interfaces.
Four-component dotted-decimal must be used for all addresses.
It
.I is
smart enough to translate bit-count netmasks to dotted-decimal form.
.PP
It would be good to have a line-continuation syntax,
especially for the very long lines involved in
RSA signature keys.
.PP
The ability to specify different identities,
.BR authby ,
and public keys for different automatic-keyed connections
between the same participants is misleading;
this doesn't work dependably because the identity of the participants
is not known early enough.
This is especially awkward for the ``Road Warrior'' case,
where the remote IP address is specified as
.BR 0.0.0.0 ,
and that is considered to be the ``participant'' for such connections.
.PP
In principle it might be necessary to control MTU on an
interface-by-interface basis,
rather than with the single global override that
.B overridemtu
provides.
.PP
A number of features which \fIcould\fR be implemented in
both manual and automatic keying
actually are not yet implemented for manual keying.
This is unlikely to be fixed any time soon.