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 fre-
quency). 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 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
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.
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.
With some cards, you may disable the ESSID checking (ESSID pro-
miscuous) 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 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
This parameter is only used for pre-802.11 hardware, the 802.11
protocol uses the ESSID and AP Address for this function.
With some cards, 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. 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
Channels are usually numbered starting at 1, and you may use
iwlist(8) to get the total number of channels, list the avail-
able frequencies, and display the current frequency as a chan-
nel. Depending on regulations, some frequencies/channels may not
iwconfig eth0 freq 2422000000
iwconfig eth0 freq 2.422G
iwconfig eth0 channel 3
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 back-
ground 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 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).
iwconfig eth0 sens -80
mode Set the operating mode of the device, which depends on the net-
work 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 acts as an Access
Point), Repeater (the node forwards packets between other wire-
less nodes), Secondary (the node acts as a backup mas-
ter/repeater), Monitor (the node acts 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 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).
You may also use off to re-enable automatic mode without chang-
ing the current Access Point, or you may use any or auto to
force the card to reassociate with the currently best Access
iwconfig eth0 ap 00:60:1D:01:23:45
iwconfig eth0 ap any
iwconfig eth0 ap off
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 configu-
ration goes. Only some diagnostic tools may use it.
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 various overhead.
You may append the suffix k, M or G to the value (decimal multi-
plier : 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 automatic bit-rate mode (fallback 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-
rates 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
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 maxi-
mum packet size disable the mechanism. You may also set this
parameter to auto, fixed or off.
iwconfig eth0 rts 250
iwconfig eth0 rts off
Fragmentation allows to split an IP packet in a burst of smaller
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 auto, fixed or off.
iwconfig eth0 frag 512
iwconfig eth0 frag off
Used to manipulate encryption or scrambling keys and security
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 not supported.
To change which key is the currently active key, just enter
[index] (without entering any key value).
off and on disable and reenable encryption.
The security mode may be open or restricted, and its meaning
depends on the card used. With most cards, in open mode no
authentication is used and the card may also accept non-
encrypted sessions, whereas in restricted mode only encrypted
sessions are accepted and the card will use authentication if
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 precedence.
iwconfig eth0 key 0123-4567-89
iwconfig eth0 key  0123-4567-89
iwconfig eth0 key s:password 
iwconfig eth0 key 
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 ups, enter period `value'. To
set the timeout before going back to sleep, enter timeout
`value'. You can also add the 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
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 broadcast 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
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 retry mechanism.
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 in milliseconds or microseconds.
You can also add the 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 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 Exten-
sions 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
This is normally not needed, because the card will eventually
apply the changes, but can be useful for debugging.
For each device which supports wireless extensions, iwconfig will dis-
play the name of the MAC protocol used (name of device for proprietary
protocols), the ESSID (Network Name), the NWID, the frequency (or chan-
nel), 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 avail-
The parameters displayed have the same meaning and values as the param-
eter you can set, please refer to the previous part for a detailed
explanation of them.
Some parameters are only displayed in short/abreviated form (such as
encryption). You may use iwlist(8) to get all the details.
Some parameters have two modes (such as bitrate). If the value is pre-
fixed by `=', it means that the parameter is fixed and forced to that
value, if it is prefixed by `:', the parameter is in automatic mode and
the current value is shown (and may change).
An address equal to 00:00:00:00:00:00 means that the card failed
to associate with an Access Point (most likely a configuration
issue). The Access Point parameter will be shown as Cell in ad-
hoc mode (for obvious reasons), but otherwise works the same.
If /proc/net/wireless exists, iwconfig will also display its content.
Note that those values will depend on the driver and the hardware
specifics, so you need to refer to your driver documentation for proper
interpretation of those values.
Overall quality of the link. May be based on the level of con-
tention or interference, the bit or frame error rate, how good
the received signal is, some timing synchronisation, or other
hardware metric. This is an aggregate value, and depends totally
on the driver and hardware.
Received signal strength (RSSI - how strong the received signal
is). May be arbitrary units or dBm, iwconfig uses driver meta
information to interpret the raw value given by /proc/net/wire-
less and display the proper unit or maximum value (using 8 bit
arithmetic). In Ad-Hoc mode, this may be undefined and you
should use iwspy.
Background noise level (when no packet is transmitted). Similar
comments as for Signal level.
Rx invalid nwid
Number of packets received with a different NWID or ESSID. Used
to detect configuration problems or adjacent network existence
(on the same frequency).
Rx invalid crypt
Number of packets that the hardware was unable to decrypt. This
can be used to detect invalid encryption settings.
Rx invalid frag
Number of packets for which the hardware was not able to prop-
erly re-assemble the link layer fragments (most likely one was
Tx excessive retries
Number of packets that the hardware failed to deliver. Most MAC
protocols will retry the packet a number of times before giving
Other packets lost in relation with specific wireless opera-
Number of periodic beacons from the Cell or the Access Point we
have missed. Beacons are sent at regular intervals to maintain
the cell coordination, failure to receive them usually indicates
that the card is out of range.
Jean Tourrilhes - jtAThpl.com
ifconfig(8), iwspy(8), iwlist(8), iwevent(8), iwpriv(8), wireless(7).
wireless-tools 22 June 2004 IWCONFIG(8)