IWCONFIG(8) Linux Programmer's Manual IWCONFIG(8)
iwconfig - configure a wireless network interface
iwconfig interface [essid X] [nwid N] [freq F] [channel C]
[sens S] [mode M] [ap A] [nick NN]
[rate R] [rts RT] [frag FT] [txpower T]
[enc E] [key K] [power P] [retry R]
Iwconfig is similar to 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). Iwconfig may also be used to display those
parameters, and the wireless statistics (extracted from /proc/net/wireless).
All these parameters and statistics are device dependant. Each driver will provide only
some of them depending on the hardware support, and the range of value may change. Please
refer to the man page of each device for details.
essid Set the ESSID (or Network Name - in some products it may also called Domain ID).
The ESSID is used to identify cells which are part of the same virtual network.
As opposed to the NWID which defines a single cell, the ESSID defines a group of
cell connected via repeaters or infrastructure, where the user may roam. With some
card, you may disable the ESSID checking (ESSID promiscuous) with off or any (and
on to reenable it).
iwconfig eth0 essid any
iwconfig eth0 essid "My Network"
Set the Network ID (in some products it is also 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 belonguing to the same
cell. With some card, you may disable the Network ID checking (NWID promiscuous)
with off (and on to reenable it).
iwconfig eth0 nwid AB34
iwconfig eth0 nwid off
Set the operating frequency or channel in the device. Value below 1000 are the
channel number, value over this is the frequency in Hz. You must append the suffix
k, M or G to the value (for example, "2.46G" for 2.46 GHz frequency), or add enough
Channels are usually numbered starting at 1, and you may use iwpriv(8) to get the
total number of channels and list the available frequencies. Depending on regula-
tions, some frequencies/channels may not be available.
iwconfig eth0 freq 2.422G
iwconfig eth0 channel 3
sens Set the sensitivity threshold. This is the lowest signal level for which we attempt
a packet reception, signal lower than this are not received. 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.
With some hardware, this parameter also control the defer threshold (lowest signal
level for which we consider the channel busy) and the handover threshold (lowest
signal level where we stay associated with the current access point).
iwconfig eth0 sens -80
mode Set the operating mode of the device, which depends on the network topology. The
mode can be Ad-hoc (network composed of only one cell and without Access Point),
Managed (node connects to a network composed of many Access Points, with roaming),
Master (the node is the synchronisation master or act as an Access Point), Repeater
(the node forward packets between other wireless nodes), Secondary (the node act as
a backup master/repeater), Monitor (the node act as a passive monitor and only
receives packets) or Auto.
iwconfig eth0 mode Managed
iwconfig eth0 mode Ad-Hoc
ap Force the card to register to the Access Point given by the address, if it is pos-
sible. When the quality of the connection goes too low, the driver may revert back
to automatic mode (the card finds the best Access Point in range).
You may also use off to re-enable automatic mode without changing the current
Access Point, or you may use any or auto to force the card to reassociate with the
current best Access Point.
iwconfig eth0 ap 00:60:1D:01:23:45
iwconfig eth0 ap any
iwconfig eth0 ap off
Set the nickname, or the station name. Most 802.11 products do define it, but this
is not used as far as the protocols (MAC, IP, TCP) are concerned and completely
accessory as far as configuration goes. In fact only some diagnostic tools may use
iwconfig eth0 nickname "My Linux Node"
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 overhead.
You must 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 auto to select the automatic bit-rate mode (fall-
back to lower rate on noisy channels), which is the default for most cards, and
fixed to revert back to fixed setting. If you specify a bit-rate value and append
auto, the driver will use all bit lower and equal than this value.
iwconfig eth0 rate 11M
iwconfig eth0 rate auto
iwconfig eth0 rate 5.5M auto
RTS/CTS adds a handshake before each packet transmission to make sure that the
channel is clear. This adds overhead, but increase performance in case of hidden
nodes or large number of active nodes. This parameters set the size of the smallest
packet for which the node sends RTS, a value equal to the maximum packet size dis-
able the scheme. You may also set this parameter to auto, fixed or off.
iwconfig eth0 rts 250
iwconfig eth0 rts off
Fragmentation allow to split a IP packet in a burst of smaller fragments transmit-
ted on the medium. In most cases this adds overhead, but in very noisy environment
this reduce the error penalty. This parameter set the maximum fragment size, a
value equal to the maximum packet size disable the scheme. You may also set this
parameter to auto, fixed or off.
iwconfig eth0 frag 512
iwconfig eth0 frag off
Used to manipulate encryption or scrambling keys and encryption mode.
To set the current encryption key, just enter the key in hex digits as XXXX-XXXX-
XXXX-XXXX or XXXXXXXX. To set a key other than the current key, prepend or append
[index] to the key itself (this won't change which is the active key). You can also
enter the key as an ASCII string by using the s: prefix. Passphrase is currently
To change which key is the current active key, just enter [index] (without entering
any key value).
off and on disable and reenable encryption, open set the system in open mode
(accept non-encrypted packets) and restricted discard non-encrypted packets.
If you need to set multiple keys, or set a key and change the active key, you need
to use multiple key directives. Arguments can be put in any order, the last one
will take precendence.
iwconfig eth0 key 0123-4567-89
iwconfig eth0 key s:password 
iwconfig eth0 key  open
iwconfig eth0 key off
iwconfig eth0 key restricted  0123456789
iwconfig eth0 key 01-23 key 45-67  key 
power Used to manipulate power management scheme parameters and mode.
To set the period between wake up, enter period `value'. To set the timeout before
going back to sleep, enter timeout `value'. You can also add the min and max modi-
fiers. By defaults, those values are in seconds, append the suffix m or u to spec-
ify values un milliseconds or microseconds. Sometimes, those values are without
units (number of dwell or the like).
off and on disable and reenable power management. Finally, you may set the power
management mode to all (receive all packets), unicast (receive unicast packets
only, discard multicast and broadcast) and multicast (receive multicast and broad-
cast only, discard unicast packets).
iwconfig eth0 power period 2
iwconfig eth0 power 500m unicast
iwconfig eth0 power timeout 300u all
iwconfig eth0 power off
iwconfig eth0 power min period 2 power max period 4
For cards supporting multiple transmit powers, set the transmit power in dBm. If W
is the power in Watt, the power in dBm is P = 30 + 10.log(W). If the value is
postfixed by mW, it will be automatically converted to dBm.
In addition, on and off enable and disable the radio, and auto and fixed enable and
disable power control (if those features are available).
iwconfig eth0 txpower 15
iwconfig eth0 txpower 30mW
iwconfig eth0 txpower auto
iwconfig eth0 txpower off
retry Most cards have MAC retransmissions, and some allow to set the behaviour of the
To set the maximum number of retries, enter limit `value'. This is an absolute
value (without unit). The set the maximum length of time the MAC should retry,
enter lifetime `value'. By defaults, this value in in seconds, append the suffix m
or u to specify values un milliseconds or microseconds.
You can also add the min and max modifiers. If the card support 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 min limit is the short retry
limit (non RTS/CTS packets).
iwconfig eth0 retry 16
iwconfig eth0 retry lifetime 300m
iwconfig eth0 retry min limit 8
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) force the card to apply all pending
This is normally not needed, because the card will eventually apply the changes,
but can be usefull for debugging.
For each device which support wireless extensions, iwconfig will display the name of the
MAC protocol used (name of device for proprietary protocols), the ESSID (Network Name),
the NWID, the frequency (or channel), the sensitivity, the mode of operation, the Access
Point address, the bit-rate the RTS threshold, the fragmentation threshold, the encryption
key and the power management settings (depending on availability).
See above for explanations of what these parameters mean.
If the label for bitrate is followed by `=', it means that the parameter is fixed and
forced to that value, if it is followed by `:' it is only the current value (device in
normal auto mode).
If /proc/net/wireless exists, iwconfig will also display its content :
Quality of the link or the modulation (what is the level of contention or interfer-
ence, or how good the received signal is).
Received signal strength (how strong the received signal is).
Background noise level (when no packet is transmited).
Number of packets received with a different NWID. Used to detect configuration
problems or adjacent network existence.
Number of packets that the hardware was unable to decrypt.
Other packets lost in relation with specific wireless operations.
Jean Tourrilhes - firstname.lastname@example.org
ifconfig(8), iwspy(8), iwlist(8), iwpriv(8), wavelan(4), wavelan_cs(4), wvlan_cs(4), net-
net-tools 31 October 1996 IWCONFIG(8)