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

       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 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 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  pro‐
	      miscuous) 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 (cre‐
	      ate 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 configu‐
	      ration goes. Only some wireless diagnostic tools may use it.
	      Example :
		   iwconfig eth0 nickname "My Linux Node"

       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  acts	as  an	Access
	      Point),  Repeater (the node forwards packets between other wire‐
	      less  nodes),  Secondary	(the  node  acts  as  a	 backup	  mas‐
	      ter/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 avail‐
	      able frequencies, and display the current frequency as  a	 chan‐
	      nel. 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 fre‐
	      quency. 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	chang‐
	      ing  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 multi‐
	      plier  :	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 sig‐
	      nal 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 associ‐
	      ated 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  con‐
	      siders 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 trans‐
	      mit. 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
	      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 noth‐
	      ing 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 maxi‐
	      mum 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 Exten‐
	      sions 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  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‐

       The parameters displayed have the same meaning and values as the param‐
       eters  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 pre‐
       fixed 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  con‐
	      tention  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/wire‐
	      less  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 prop‐
	      erly re-assemble the link layer fragments (most likely  one  was

       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 opera‐

       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).

wireless-tools			 30 March 2006			   IWCONFIG(8)

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