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iwconfig

IWCONFIG(8)                Linux Programmer's Manual               IWCONFIG(8)



NAME
       iwconfig - configure a wireless network interface

SYNOPSIS
       iwconfig [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]
                          [commit]
       iwconfig --help
       iwconfig --version

DESCRIPTION
       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 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.

PARAMETERS
       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 infrastruc-
              ture, 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).
              Examples :
                   iwconfig eth0 essid any
                   iwconfig eth0 essid "My Network"

       nwid/domain
              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).
              Examples :
                   iwconfig eth0 nwid AB34
                   iwconfig eth0 nwid off

       freq/channel
              Set  the  operating  frequency  or  channel in the device. Value
              below 1000 are the channel number, value over this is  the  fre-
              quency  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
              '0'.
              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 regulations, some frequen-
              cies/channels may not be available.
              Examples :
                   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).
              Example :
                   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 act as an Access
              Point), Repeater (the node forward packets between  other  wire-
              less   nodes),   Secondary  (the  node  act  as  a  backup  mas-
              ter/repeater), Monitor (the node act as a  passive  monitor  and
              only receives packets) or Auto.
              Example :
                   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 finds 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  current  best  Access
              Point.
              Example :
                   iwconfig eth0 ap 00:60:1D:01:23:45
                   iwconfig eth0 ap any
                   iwconfig eth0 ap off

       nick[name]
              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 con-
              figuration goes. In fact only some diagnostic tools may use  it.
              Example :
                   iwconfig eth0 nickname "My Linux Node"

       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 overhead.
              You must append the suffix k, M or G to the value (decimal  mul-
              tiplier  :  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 (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
              lower and equal than this value.
              Examples :
                   iwconfig eth0 rate 11M
                   iwconfig eth0 rate auto
                   iwconfig eth0 rate 5.5M auto

       rts[_threshold]
              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 disable the scheme. You may  also  set  this  parameter  to
              auto, fixed or off.
              Examples :
                   iwconfig eth0 rts 250
                   iwconfig eth0 rts off

       frag[mentation_threshold]
              Fragmentation  allow  to split a IP packet in a burst of smaller
              fragments transmitted 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.
              Examples :
                   iwconfig eth0 frag 512
                   iwconfig eth0 frag off

       key/enc[ryption]
              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 not supported.
              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  dis-
              card 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.
              Examples :
                   iwconfig eth0 key 0123-4567-89
                   iwconfig eth0 key s:password [2]
                   iwconfig eth0 key [2] 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 up, 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  defaults,  those
              values  are in seconds, append the suffix m or u to specify val-
              ues 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 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 off
                   iwconfig eth0 power min period 2 power max period 4

       txpower
              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).
              Examples :
                   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 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).
              Examples :
                   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) force the card  to  apply  all  pending
              changes.
              This  is  normally  not needed, because the card will eventually
              apply the changes, but can be usefull for debugging.

DISPLAY
       For each device which support 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-
       ability).
       See above for explanations of what these parameters mean.
       If the label for bitrate is followed by `=', it means that the  parame-
       ter  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 :

       Link quality
              Quality of the link or the modulation (what is the level of con-
              tention or interference, or how good the received signal is).

       Signal level
              Received signal strength (how strong the received signal is).

       Noise level
              Background noise level (when no packet is transmited).

       invalid nwid
              Number of packets received with a different NWID. Used to detect
              configuration problems or adjacent network existence.

       invalid crypt
              Number of packets that the hardware was unable to decrypt.

       invalid misc
              Other packets lost in relation  with  specific  wireless  opera-
              tions.

AUTHOR
       Jean Tourrilhes - jt@hpl.hp.com

FILES
       /proc/net/wireless

SEE ALSO
       ifconfig(8), iwspy(8), iwlist(8), iwpriv(8), wavelan(4), wavelan_cs(4),
       wvlan_cs(4), netwave_cs(4).



net-tools                       31 October 1996                    IWCONFIG(8)