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       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).