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

NAME
       iwconfig - configure a wireless network interface

SYNOPSIS
       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

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  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.

PARAMETERS
       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

       nick[name]
	      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
	      it.
	      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

       freq/channel
	      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 set-
	      ting 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 sup-
	      ported).
	      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  pos-
	      sible.  This address is the cell identity of the Access Point, as reported by wire-
	      less 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

       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 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

       txpower
	      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 oper-
	      ating 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 look-
	      ing 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 low-
	      est signal level for which the hardware considers the channel busy.  Signal  levels
	      above  this  threshold make the hardware inhibits its own transmission whereas sig-
	      nals 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 transmis-
	      sions. 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 max-
	      imum  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	millisec-
	      onds or microseconds.
	      You can also add the short, long, min and max modifiers. If the card supports auto-
	      matic 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[_threshold]
	      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 small-
	      est  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

       frag[mentation_threshold]
	      Fragmentation allows to split an IP packet in a burst of smaller	fragments  trans-
	      mitted  on  the medium. In most cases this adds overhead, but in a very noisy envi-
	      ronment this reduces the error penalty and allow packets to get  through	interfer-
	      ence  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 frag-
	      ment 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

       key/enc[ryption]
	      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 enter-
	      ing 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 broad-
	      cast 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

       modu[lation]
	      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 propri-
	      etary. 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 issues.
	      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.

DISPLAY
       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 encryp-
       tion 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 val-
       ues 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 interfer-
	      ence, 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  arbi-
	      trary  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 configu-
	      ration 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. Bea-
	      cons are sent at regular intervals to maintain the cell  coordination,  failure  to
	      receive them usually indicates that the card is out of range.

AUTHOR
       Jean Tourrilhes - jt@hpl.hp.com

FILES
       /proc/net/wireless

SEE ALSO
       ifconfig(8), iwspy(8), iwlist(8), iwevent(8), iwpriv(8), wireless(7).

wireless-tools				  30 March 2006 			      IWCONFIG(8)
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