iwconfig - configure a wireless network interface


   iwconfig [interface]
   iwconfig interface [essid X] [nwid N] [mode M] [freq F]
                      [channel C][sens S ][ap A ][nick NN ]
                      [rate R] [rts RT] [frag FT] [txpower T]
                      [enc E] [key K] [power P] [retry R]
                      [modu M] [commit]
   iwconfig --help
   iwconfig --version


   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 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.


   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
          promiscuous) with off or any (and on to reenable it).
          If  the  ESSID  of  your  network is one of the special keywords
          (off, on or any), you should use -- to escape it.
          Examples :
               iwconfig eth0 essid any
               iwconfig eth0 essid "My Network"
               iwconfig eth0 essid -- "ANY"

   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.
          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).
          Examples :
               iwconfig eth0 nwid AB34
               iwconfig eth0 nwid 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
          configuration goes. Only some wireless diagnostic tools may  use
          Example :
               iwconfig eth0 nickname "My Linux Node"

   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 acts as an
          Access Point), Repeater (the node forwards packets between other
          wireless   nodes),   Secondary   (the  node  acts  as  a  backup
          master/repeater), Monitor (the node is not associated  with  any
          cell  and  passively  monitor  all  packets on the frequency) or
          Example :
               iwconfig eth0 mode Managed
               iwconfig eth0 mode Ad-Hoc

          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'.
          Channels are usually numbered starting at 1,  and  you  may  use
          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.
          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.
          You may also use off or auto to let the card pick  up  the  best
          channel (when supported).
          Examples :
               iwconfig eth0 freq 2422000000
               iwconfig eth0 freq 2.422G
               iwconfig eth0 channel 3
               iwconfig eth0 channel auto

   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.
          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
          changing the current Access Point, or you may use any or auto to
          force the card to reassociate with  the  currently  best  Access
          Example :
               iwconfig eth0 ap 00:60:1D:01:23:45
               iwconfig eth0 ap any
               iwconfig eth0 ap off

          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
          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 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.
          Examples :
               iwconfig eth0 rate 11M
               iwconfig eth0 rate auto
               iwconfig eth0 rate 5.5M auto

          For cards supporting multiple transmit powers, sets 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).
          Examples :
               iwconfig eth0 txpower 15
               iwconfig eth0 txpower 30mW
               iwconfig eth0 txpower auto
               iwconfig eth0 txpower off

   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.
          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.
          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.
          Example :
               iwconfig eth0 sens -80
               iwconfig eth0 sens 2

   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),  and the default (when
          nothing is specified).  To set the maximum length  of  time  the
          MAC  should  retry,  enter  lifetime `value'.  By defaults, this
          value is in seconds, append the suffix m or u to specify  values
          in milliseconds or microseconds.
          You  can also add the 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 min limit is the
          short retry limit (non RTS/CTS packets).
          Examples :
               iwconfig eth0 retry 16
               iwconfig eth0 retry lifetime 300m
               iwconfig eth0 retry short 12
               iwconfig eth0 retry min limit 8

          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 disables the mechanism.  You  may  also  set
          this parameter to auto, fixed or off.
          Examples :
               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 which is always
          lower than the maximum packet size.
          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.
          You may also set this parameter to auto, fixed or off.
          Examples :
               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.
          Examples :
               iwconfig eth0 key 0123-4567-89
               iwconfig eth0 key [3] 0123-4567-89
               iwconfig eth0 key s:password [2]
               iwconfig eth0 key [2]
               iwconfig eth0 key open
               iwconfig eth0 key off
               iwconfig eth0 key restricted [3] 0123456789
               iwconfig eth0 key 01-23 key 45-67 [4] key [4]

   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'.  To set the generic level of power saving, enter saving
          `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,
          percentage or similar).
          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).
          Examples :
               iwconfig eth0 power period 2
               iwconfig eth0 power 500m unicast
               iwconfig eth0 power timeout 300u all
               iwconfig eth0 power saving 3
               iwconfig eth0 power off
               iwconfig eth0 power min period 2 power max period 4

          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
          The  list of available modulations depend on the card/driver and
          can be  displayed  using  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 auto let the card/driver do its best.
          Examples :
               iwconfig eth0 modu 11g
               iwconfig eth0 modu CCK OFDMa
               iwconfig eth0 modu auto

   commit Some   cards   may  not  apply  changes  done  through  Wireless
          Extensions immediately (they may wait to aggregate  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.
          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
   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).

   The parameters displayed have  the  same  meaning  and  values  as  the
   parameters  you  can  set,  please  refer  to  the  previous part for a
   detailed explanation of them.
   Some parameters are only displayed in short/abbreviated 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
   prefixed 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).

   Access Point/Cell
          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.

   Link quality
          Overall quality of the link.  May  be  based  on  the  level  of
          contention  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.

   Signal level
          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/wireless  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.

   Noise level
          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
          properly re-assemble the link layer fragments (most  likely  one
          was missing).

   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

   Invalid misc
          Other   packets   lost   in   relation  with  specific  wireless

   Missed beacon
          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 -




   ifconfig(8), iwspy(8), iwlist(8), iwevent(8), iwpriv(8), wireless(7).


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