.\" Jean II - HPLB - 1996 => HPL - 2004
.\" iwconfig.8
.\"
-.TH IWCONFIG 8 "22 June 2004" "wireless-tools" "Linux Programmer's Manual"
+.TH IWCONFIG 8 "30 March 2006" "wireless-tools" "Linux Programmer's Manual"
.\"
.\" NAME part
.\"
.SH SYNOPSIS
.BI "iwconfig [" interface ]
.br
-.BI "iwconfig " interface " [essid " X "] [nwid " N "] [freq " F "] [channel " C ]
+.BI "iwconfig " interface " [essid " X "] [nwid " N "] [mode " M "] [freq " F "]
.br
-.BI " [sens " S "] [mode " M "] [ap " A "] [nick " NN ]
+.BI " [channel " C ] [sens " S "] [ap " A "] [nick " NN ]
.br
.BI " [rate " R "] [rts " RT "] [frag " FT "] [txpower " T ]
.br
.BI " [enc " E "] [key " K "] [power " P "] [retry " R ]
.br
-.BI " [commit]
+.BI " [modu " M "] [commit]
.br
.BI "iwconfig --help"
.br
.IR off " or " any " (and " on
to reenable it).
.br
+If the ESSID of your network is one of the special keywords
+.RI ( off ", " on " or " any ),
+you should use
+.I --
+to escape it.
+.br
.B Examples :
.br
.I " iwconfig eth0 essid any"
.br
.I " iwconfig eth0 essid ""My Network""
+.br
+.I " iwconfig eth0 essid -- ""ANY""
.TP
-.BR nwid / domain
-Set the Network ID (in some products it may also be called Domain
-ID). As all adjacent wireless networks share the same medium, this
-parameter is used to differenciate them (create logical colocated
-networks) and identify nodes belonging to the same cell.
+.BR nwid
+Set the Network ID. As all adjacent wireless networks share the same
+medium, this parameter is used to differentiate them (create logical
+colocated networks) and identify nodes belonging to the same cell.
.br
This parameter is only used for pre-802.11 hardware, the 802.11
protocol uses the ESSID and AP Address for this function.
.br
.I " iwconfig eth0 nwid off"
.TP
-.BR freq / channel
-Set the operating frequency or channel in the device. A value below
-1000 indicates a channel number, a value greater than 1000 is a
-frequency in Hz. You may append the suffix k, M or G to the value (for
-example, "2.46G" for 2.46 GHz frequency), or add enough '0'.
-.br
-Channels are usually numbered starting at 1, and you may use
-.IR iwlist (8)
-to get the total number of channels, list the available frequencies,
-and display the current frequency as a channel. Depending on
-regulations, some frequencies/channels may not be available.
-.br
-.B Examples :
-.br
-.I " iwconfig eth0 freq 2422000000"
-.br
-.I " iwconfig eth0 freq 2.422G"
-.br
-.I " iwconfig eth0 channel 3"
-.TP
-.B sens
-Set the sensitivity threshold. This is the lowest signal level for
-which the hardware attempt packet reception, signals weaker than this
-are ignored. This is used to avoid receiving background noise, so you
-should set it according to the average noise level. Positive values
-are assumed to be the raw value used by the hardware or a percentage,
-negative values are assumed to be dBm.
-.br
-With some hardware, this parameter also controls the defer threshold
-(lowest signal level for which the hardware consider the channel busy)
-and the handover threshold (signal level where the hardware start
-looking for a new access point).
+.BR nick [name]
+Set the nickname, or the station name. Some 802.11 products do define
+it, but this is not used as far as the protocols (MAC, IP, TCP) are
+concerned and completely useless as far as configuration goes. Only
+some wireless diagnostic tools may use it.
.br
.B Example :
.br
-.I " iwconfig eth0 sens -80"
+.I " iwconfig eth0 nickname ""My Linux Node""
.TP
.B mode
Set the operating mode of the device, which depends on the network
.I Secondary
(the node acts as a backup master/repeater),
.I Monitor
-(the node acts as a passive monitor and only receives packets) or
+(the node is not associated with any cell and passively monitor all
+packets on the frequency) or
.IR Auto .
.br
.B Example :
.br
.I " iwconfig eth0 mode Ad-Hoc"
.TP
+.BR freq / channel
+Set the operating frequency or channel in the device. A value below
+1000 indicates a channel number, a value greater than 1000 is a
+frequency in Hz. You may append the suffix k, M or G to the value (for
+example, "2.46G" for 2.46 GHz frequency), or add enough '0'.
+.br
+Channels are usually numbered starting at 1, and you may use
+.IR iwlist (8)
+to get the total number of channels, list the available frequencies,
+and display the current frequency as a channel. Depending on
+regulations, some frequencies/channels may not be available.
+.br
+When using Managed mode, most often the Access Point dictates the
+channel and the driver may refuse the setting of the frequency. In
+Ad-Hoc mode, the frequency setting may only be used at initial cell
+creation, and may be ignored when joining an existing cell.
+.br
+You may also use
+.I off
+or
+.I auto
+to let the card pick up the best channel (when supported).
+.br
+.B Examples :
+.br
+.I " iwconfig eth0 freq 2422000000"
+.br
+.I " iwconfig eth0 freq 2.422G"
+.br
+.I " iwconfig eth0 channel 3"
+.br
+.I " iwconfig eth0 channel auto"
+.TP
.B ap
Force the card to register to the Access Point given by the address,
-if it is possible. When the quality of the connection goes too low,
-the driver may revert back to automatic mode (the card selects the
-best Access Point in range).
+if it is possible. This address is the cell identity of the Access
+Point, as reported by wireless scanning, which may be different from
+its network MAC address. If the wireless link is point to point, set
+the address of the other end of the link. If the link is ad-hoc, set
+the cell identity of the ad-hoc network.
+.br
+When the quality of the connection goes too low, the driver may revert
+back to automatic mode (the card selects the best Access Point in
+range).
.br
You may also use
.I off
.br
.I " iwconfig eth0 ap off"
.TP
-.BR nick [name]
-Set the nickname, or the station name. Some 802.11 products do define
-it, but this is not used as far as the protocols (MAC, IP, TCP) are
-concerned and completely useless as far as configuration goes. Only
-some diagnostic tools may use it.
-.br
-.B Example :
-.br
-.I " iwconfig eth0 nickname ""My Linux Node""
-.TP
.BR rate / bit [rate]
For cards supporting multiple bit rates, set the bit-rate in b/s. The
bit-rate is the speed at which bits are transmitted over the medium,
.br
.I " iwconfig eth0 rate 5.5M auto"
.TP
+.BR txpower
+For cards supporting multiple transmit powers, sets the transmit power
+in dBm. If
+.I W
+is the power in Watt, the power in dBm is
+.IR "P = 30 + 10.log(W)" .
+If the value is postfixed by
+.IR mW ,
+it will be automatically converted to dBm.
+.br
+In addition,
+.IR on " and " off
+enable and disable the radio, and
+.IR auto " and " fixed
+enable and disable power control (if those features are available).
+.br
+.B Examples :
+.br
+.I " iwconfig eth0 txpower 15"
+.br
+.I " iwconfig eth0 txpower 30mW"
+.br
+.I " iwconfig eth0 txpower auto"
+.br
+.I " iwconfig eth0 txpower off"
+.TP
+.B sens
+Set the sensitivity threshold. This define how sensitive is the card
+to poor operating conditions (low signal, interference). Positive
+values are assumed to be the raw value used by the hardware or a
+percentage, negative values are assumed to be dBm. Depending on the
+hardware implementation, this parameter may control various functions.
+.br
+On modern cards, this parameter usually control handover/roaming
+threshold, the lowest signal level for which the hardware remains
+associated with the current Access Point. When the signal level goes
+below this threshold the card starts looking for a new/better Access
+Point. Some cards may use the number of missed beacons to trigger
+this. For high density of Access Points, a higher threshold make sure
+the card is always associated with the best AP, for low density of
+APs, a lower threshold minimise the number of failed handoffs.
+.br
+On more ancient card this parameter usually controls the defer
+threshold, the lowest signal level for which the hardware considers
+the channel busy. Signal levels above this threshold make the hardware
+inhibits its own transmission whereas signals weaker than this are
+ignored and the hardware is free to transmit. This is usually strongly
+linked to the receive threshold, the lowest signal level for which the
+hardware attempts packet reception. Proper setting of these thresholds
+prevent the card to waste time on background noise while still
+receiving weak transmissions. Modern designs seems to control those
+thresholds automatically.
+.br
+.br
+.B Example :
+.br
+.I " iwconfig eth0 sens -80"
+.br
+.I " iwconfig eth0 sens 2"
+.TP
+.BR retry
+Most cards have MAC retransmissions, and some allow to set the
+behaviour of the retry mechanism.
+.br
+To set the maximum number of retries, enter
+.IR "limit `value'" .
+This is an absolute value (without unit), and the default (when
+nothing is specified).
+To set the maximum length of time the MAC should retry, enter
+.IR "lifetime `value'" .
+By defaults, this value is in seconds, append the suffix m or u to
+specify values in milliseconds or microseconds.
+.br
+You can also add the
+.IR short ", " long ", " min " and " max
+modifiers. If the card supports automatic mode, they define the bounds
+of the limit or lifetime. Some other cards define different values
+depending on packet size, for example in 802.11
+.I min limit
+is the short retry limit (non RTS/CTS packets).
+.br
+.B Examples :
+.br
+.I " iwconfig eth0 retry 16"
+.br
+.I " iwconfig eth0 retry lifetime 300m"
+.br
+.I " iwconfig eth0 retry short 12"
+.br
+.I " iwconfig eth0 retry min limit 8"
+.TP
.BR rts [_threshold]
RTS/CTS adds a handshake before each packet transmission to make sure
that the channel is clear. This adds overhead, but increases
performance in case of hidden nodes or a large number of active
nodes. This parameter sets the size of the smallest packet for which
-the node sends RTS ; a value equal to the maximum packet size disable
+the node sends RTS ; a value equal to the maximum packet size disables
the mechanism. You may also set this parameter to
.IR auto ", " fixed " or " off .
.br
fragments transmitted on the medium. In most cases this adds overhead,
but in a very noisy environment this reduces the error penalty and
allow packets to get through interference bursts. This parameter sets
-the maximum fragment size ; a value equal to the maximum packet size
-disable the mechanism. You may also set this parameter to
+the maximum fragment size which is always lower than the maximum
+packet size.
+.br
+This parameter may also control Frame Bursting available on some
+cards, the ability to send multiple IP packets together. This
+mechanism would be enabled if the fragment size is larger than the
+maximum packet size.
+.br
+You may also set this parameter to
.IR auto ", " fixed " or " off .
.br
.B Examples :
.IR "period `value'" .
To set the timeout before going back to sleep, enter
.IR "timeout `value'" .
+To set the generic level of power saving, enter
+.IR "saving `value'" .
You can also add the
.IR min " and " max
modifiers. By default, those values are in seconds, append the suffix
m or u to specify values in milliseconds or microseconds. Sometimes,
-those values are without units (number of beacon periods, dwell or
-similar).
+those values are without units (number of beacon periods, dwell,
+percentage or similar).
.br
.IR off " and " on
disable and reenable power management. Finally, you may set the power
.br
.I " iwconfig eth0 power timeout 300u all"
.br
+.I " iwconfig eth0 power saving 3"
+.br
.I " iwconfig eth0 power off"
.br
.I " iwconfig eth0 power min period 2 power max period 4"
.TP
-.BR txpower
-For cards supporting multiple transmit powers, set the transmit power in dBm. If
-.I W
-is the power in Watt, the power in dBm is
-.IR "P = 30 + 10.log(W)" .
-If the value is postfixed by
-.IR mW ,
-it will be automatically converted to dBm.
-.br
-In addition,
-.IR on " and " off
-enable and disable the radio, and
-.IR auto " and " fixed
-enable and disable power control (if those features are available).
-.br
-.B Examples :
-.br
-.I " iwconfig eth0 txpower 15"
-.br
-.I " iwconfig eth0 txpower 30mW"
-.br
-.I " iwconfig eth0 txpower auto"
-.br
-.I " iwconfig eth0 txpower off"
-.TP
-.BR retry
-Most cards have MAC retransmissions, and some allow to set the
-behaviour of the retry mechanism.
-.br
-To set the maximum number of retries, enter
-.IR "limit `value'" .
-This is an absolute value (without unit).
-The set the maximum length of time the MAC should retry, enter
-.IR "lifetime `value'" .
-By defaults, this value in in seconds, append the suffix m or u to
-specify values in milliseconds or microseconds.
-.br
-You can also add the
-.IR min " and " max
-modifiers. If the card supports automatic mode, they define the bounds
-of the limit or lifetime. Some other cards define different values
-depending on packet size, for example in 802.11
-.I min limit
-is the short retry limit (non RTS/CTS packets).
+.BR modu [lation]
+Force the card to use a specific set of modulations. Modern cards
+support various modulations, some which are standard, such as 802.11b
+or 802.11g, and some proprietary. This command force the card to only
+use the specific set of modulations listed on the command line. This
+can be used to fix interoperability issues.
+.br
+The list of available modulations depend on the card/driver and can be
+displayed using
+.IR "iwlist modulation" .
+Note that some card/driver may not be able to select each modulation
+listed independently, some may come as a group. You may also set this
+parameter to
+.IR auto
+let the card/driver do its best.
.br
.B Examples :
.br
-.I " iwconfig eth0 retry 16"
+.I " iwconfig eth0 modu 11g"
.br
-.I " iwconfig eth0 retry lifetime 300m"
+.I " iwconfig eth0 modu CCK OFDMa"
.br
-.I " iwconfig eth0 retry min limit 8"
+.I " iwconfig eth0 modu auto"
.TP
.BR commit
Some cards may not apply changes done through Wireless Extensions
-immediately (they may wait to agregate the changes or apply it only
-when the card is brought up via ifconfig). This command (when
-available) forces the card to apply all pending changes.
+immediately (they may wait to aggregate the changes or apply it only
+when the card is brought up via
+.IR ifconfig ).
+This command (when available) forces the card to apply all pending
+changes.
.br
This is normally not needed, because the card will eventually apply
the changes, but can be useful for debugging.
of operation, the
.B Access Point
address, the
-.B bit-rate
+.BR bit-rate ,
the
.BR "RTS threshold" ", the " "fragmentation threshold" ,
the
settings (depending on availability).
.PP
The parameters displayed have the same meaning and values as the
-parameter you can set, please refer to the previous part for a
+parameters you can set, please refer to the previous part for a
detailed explanation of them.
.br
-Some parameters are only displayed in short/abreviated form (such as
+Some parameters are only displayed in short/abbreviated form (such as
encryption). You may use
.IR iwlist (8)
to get all the details.
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