Provided by: wireless-tools_30~pre9-12ubuntu1_amd64 bug


       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
              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 Auto.
              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
              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 Point.
              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 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  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 available.
              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
              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

       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

       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 up.

       Invalid misc
              Other packets lost in relation with specific wireless operations.

       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).