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       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]
       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 wire­
       less 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  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.


       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
              As opposed to the NWID which defines a single cell,
              the  ESSID  defines  a  group of cell connected via
              repeaters or infrastructure,  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"

              Set  the  Network  ID  (in some products it is also
              called Domain ID). As all  adjacent  wireless  net­
              works 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


       sens   Set  the  sensitivity threshold. This is the lowest
              signal level for which we attempt a  packet  recep­
              tion, 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 val­
              ues 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 thresh­
              old  (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  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), Mas­
              ter  (the node is the synchronisation master or act
              as an Access Point),  Repeater  (the  node  forward
              packets  between  other  wireless nodes), Secondary
              (the node act as a backup master/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  changing  the current Access Point, or you
              may use any or auto to force the card to  reassoci­
              ate with the current best Access Point.
              Example :
                   iwconfig eth0 ap 00:60:1D:01:23:45
                   iwconfig eth0 ap any
                   iwconfig eth0 ap off

              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 configuration  goes.
              In fact only some diagnostic tools may use it.
              back 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/CTS adds a handshake before each packet  trans­
              mission  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

              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

              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 current 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 depend on  the  card  used.  With  most
              card,  in  open  mode no authentication is used and
                   iwconfig eth0 key 01-23 key 45-67 [4] key [4]

       power  Used to manipulate power management scheme  parame­
              ters 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
              values 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

              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 automati­
              cally 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
              eventually  apply  the  changes, but can be usefull
              for debugging.


       For each device which support wireless extensions,  iwcon­
       fig  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 sensitiv­
       ity, 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).
       See  above for explanations of what these parameters mean.
       If the label for some values (such as bitrate) is followed
       by `=', it means that the parameter is fixed and forced to
       that value, if it is followed by `:' it is only  the  cur­
       rent value (device in normal auto mode).

       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 met­
              ric. This is an aggregate value, and depend 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 dis­
              play 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  trans­
              mited). 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
              Other packets lost in relation with specific  wire­
              less operations.

       Missed beacon
              Number  of  periodic  beacons  from the Cell or the
              Access Point we have missed. Beacons  are  sent  at
              regular interval to maintain the cell coordination,
              failure to receive them usually  indicate  that  we
              are out of range.


       Jean Tourrilhes - jt@hpl.hp.com




       ifconfig(8),  iwspy(8),  iwlist(8), iwevent(8), iwpriv(8),

net-tools                31 October 1996              IWCONFIG(8)



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