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    Command:

    iwconfig

    
    
    

    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 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.
    
    
    

    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 (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
    
           nick[name]
                  Set  the  nickname, or the station name. Some 802.11 products do
                  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 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
                  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.
                  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
                  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 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
                  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
    
           frag[mentation_threshold]
                  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
    
           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 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
    
                  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
    
           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 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
                  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 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
                  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  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).
    
           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
           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
                  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 opera-
                  tions.
    
           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.
    
    
    

    AUTHOR

           Jean Tourrilhes - jt@hpl.hp.com
    
    
    

    FILES

    
    
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