iwconfig.8

This package contains the Wireless tools, used to manipulate the Wireless Extensions. The Wireless

.\" Jean II - HPLB - 1996 => HPL - 2004
.\" iwconfig.8
.\"
.TH IWCONFIG 8 "09 March 2006" "wireless-tools" "Linux Programmer's Manual"
.\"
.\" NAME part
.\"
.SH NAME
iwconfig \- configure a wireless network interface
.\"
.\" SYNOPSIS part
.\"
.SH SYNOPSIS
.BI "iwconfig [" interface ]
.br
.BI "iwconfig " interface " [essid " X "] [nwid " N "] [mode " M "] [freq " F "]
.br
.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]
.br
.BI "iwconfig --help"
.br
.BI "iwconfig --version"
.\"
.\" DESCRIPTION part
.\"
.SH DESCRIPTION
.B Iwconfig
is similar to
.IR ifconfig (8),
but is dedicated to the wireless interfaces. It is used to set the
parameters of the network interface which are specific to the wireless
operation (for example : the frequency).
.B Iwconfig
may also be used to display those parameters, and the wireless
statistics (extracted from
.IR /proc/net/wireless ).
.PP
All these parameters and statistics are device dependent. Each driver
will provide only some of them depending on hardware support, and the
range of values may change. Please refer to the man page of each
device for details.
.\"
.\" PARAMETER part
.\"
.SH PARAMETERS
.TP
.B essid
Set the ESSID (or Network Name - in some products it may also be
called Domain ID). The ESSID is used to identify cells which are part
of the same virtual network.
.br
As opposed to the AP Address or NWID which define a single cell, the
ESSID defines a group of cells connected via repeaters or
infrastructure, where the user may roam transparently.
.br
With some cards, you may disable the ESSID checking (ESSID
promiscuous) with
.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
This parameter is only used for pre-802.11 hardware, the 802.11
protocol uses the ESSID and AP Address for this function.
.br
With some cards, you may disable the Network ID checking (NWID
promiscuous) with
.IR off " (and " on
to reenable it).
.br
.B Examples :
.br
.I "	iwconfig eth0 nwid AB34
.br
.I "	iwconfig eth0 nwid 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 wireless diagnostic tools may use it.
.br
.B Example :
.br
.I "	iwconfig eth0 nickname ""My Linux Node""
.TP
.B mode
Set the operating mode of the device, which depends on the network
topology. The mode can be
.I Ad-Hoc
(network composed of only one cell and without Access Point),
.I Managed
(node connects to a network composed of many Access Points, with roaming),
.I Master
(the node is the synchronisation master or acts as an Access Point),
.I Repeater
(the node forwards packets between other wireless nodes),
.I Secondary
(the node acts as a backup master/repeater),
.I Monitor
(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 Managed"
.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. 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
to re-enable automatic mode without changing the current Access Point,
or you may use
.I any
or
.I auto
to force the card to reassociate with the currently best Access Point.
.br
.B Example :
.br
.I "	iwconfig eth0 ap 00:60:1D:01:23:45"
.br
.I "	iwconfig eth0 ap any"
.br
.I "	iwconfig eth0 ap off"
.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,
the user speed of the link is lower due to medium sharing and
various overhead.
.br
You may append the suffix k, M or G to the value (decimal multiplier :
10^3, 10^6 and 10^9 b/s), or add enough '0'. Values below 1000 are
card specific, usually an index in the bit-rate list. Use
.I auto
to select automatic bit-rate mode (fallback to lower rate on noisy
channels), which is the default for most cards, and
.I fixed
to revert back to fixed setting. If you specify a bit-rate value and append
.IR auto ,
the driver will use all bit-rates lower and equal than this value.
.br
.B Examples :
.br
.I "	iwconfig eth0 rate 11M"
.br
.I "	iwconfig eth0 rate auto"
.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).
To set the maximum length of time the MAC should retry, enter