1IWCONFIG(8)                Linux Programmer's Manual               IWCONFIG(8)
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NAME

6       iwconfig - configure a wireless network interface
7

SYNOPSIS

9       iwconfig [interface]
10       iwconfig interface [essid X] [nwid N] [mode M] [freq F]
11                          [channel C][sens S ][ap A ][nick NN ]
12                          [rate R] [rts RT] [frag FT] [txpower T]
13                          [enc E] [key K] [power P] [retry R]
14                          [modu M] [commit]
15       iwconfig --help
16       iwconfig --version
17

DESCRIPTION

19       Iwconfig  is  similar  to ifconfig(8), but is dedicated to the wireless
20       interfaces. It is used to set the parameters of the  network  interface
21       which  are  specific  to the wireless operation (for example : the fre‐
22       quency).  Iwconfig may also be used to display  those  parameters,  and
23       the wireless statistics (extracted from /proc/net/wireless).
24
25       All  these  parameters and statistics are device dependent. Each driver
26       will provide only some of them depending on hardware support,  and  the
27       range of values may change. Please refer to the man page of each device
28       for details.
29

PARAMETERS

31       essid  Set the ESSID (or Network Name - in some products it may also be
32              called Domain ID). The ESSID is used to identify cells which are
33              part of the same virtual network.
34              As opposed to the AP Address or NWID which define a single cell,
35              the  ESSID  defines  a group of cells connected via repeaters or
36              infrastructure, where the user may roam transparently.
37              With some cards, you may disable the ESSID checking (ESSID  pro‐
38              miscuous) with off or any (and on to reenable it).
39              If  the  ESSID  of  your  network is one of the special keywords
40              (off, on or any), you should use -- to escape it.
41              Examples :
42                   iwconfig eth0 essid any
43                   iwconfig eth0 essid "My Network"
44                   iwconfig eth0 essid -- "ANY"
45
46       nwid   Set the Network ID. As all adjacent wireless networks share  the
47              same  medium, this parameter is used to differentiate them (cre‐
48              ate logical colocated networks) and identify nodes belonging  to
49              the same cell.
50              This  parameter is only used for pre-802.11 hardware, the 802.11
51              protocol uses the ESSID and AP Address for this function.
52              With some cards, you may disable the Network ID  checking  (NWID
53              promiscuous) with off (and on to reenable it).
54              Examples :
55                   iwconfig eth0 nwid AB34
56                   iwconfig eth0 nwid off
57
58       nick[name]
59              Set  the  nickname, or the station name. Some 802.11 products do
60              define it, but this is not used as far as  the  protocols  (MAC,
61              IP, TCP) are concerned and completely useless as far as configu‐
62              ration goes. Only some wireless diagnostic tools may use it.
63              Example :
64                   iwconfig eth0 nickname "My Linux Node"
65
66       mode   Set the operating mode of the device, which depends on the  net‐
67              work  topology. The mode can be Ad-Hoc (network composed of only
68              one cell and without Access Point), Managed (node connects to  a
69              network  composed  of  many Access Points, with roaming), Master
70              (the node is the synchronisation master or  acts  as  an  Access
71              Point),  Repeater (the node forwards packets between other wire‐
72              less  nodes),  Secondary  (the  node  acts  as  a  backup   mas‐
73              ter/repeater), Monitor (the node is not associated with any cell
74              and passively monitor all packets on the frequency) or Auto.
75              Example :
76                   iwconfig eth0 mode Managed
77                   iwconfig eth0 mode Ad-Hoc
78
79       freq/channel
80              Set the operating frequency or channel in the  device.  A  value
81              below 1000 indicates a channel number, a value greater than 1000
82              is a frequency in Hz. You may append the suffix k, M or G to the
83              value  (for  example,  "2.46G"  for  2.46 GHz frequency), or add
84              enough '0'.
85              Channels are usually numbered starting at 1,  and  you  may  use
86              iwlist(8)  to  get the total number of channels, list the avail‐
87              able frequencies, and display the current frequency as  a  chan‐
88              nel. Depending on regulations, some frequencies/channels may not
89              be available.
90              When using Managed mode, most often the  Access  Point  dictates
91              the  channel  and  the driver may refuse the setting of the fre‐
92              quency. In Ad-Hoc mode, the frequency setting may only  be  used
93              at  initial  cell  creation,  and may be ignored when joining an
94              existing cell.
95              You may also use off or auto to let the card pick  up  the  best
96              channel (when supported).
97              Examples :
98                   iwconfig eth0 freq 2422000000
99                   iwconfig eth0 freq 2.422G
100                   iwconfig eth0 channel 3
101                   iwconfig eth0 channel auto
102
103       ap     Force  the  card  to  register  to the Access Point given by the
104              address, if it is possible. This address is the cell identity of
105              the Access Point, as reported by wireless scanning, which may be
106              different from its network MAC address. If the wireless link  is
107              point to point, set the address of the other end of the link. If
108              the link is ad-hoc, set the cell identity of the ad-hoc network.
109              When the quality of the connection goes too low, the driver  may
110              revert  back to automatic mode (the card selects the best Access
111              Point in range).
112              You may also use off to re-enable automatic mode without  chang‐
113              ing  the  current  Access  Point,  or you may use any or auto to
114              force the card to reassociate with  the  currently  best  Access
115              Point.
116              Example :
117                   iwconfig eth0 ap 00:60:1D:01:23:45
118                   iwconfig eth0 ap any
119                   iwconfig eth0 ap off
120
121       rate/bit[rate]
122              For  cards  supporting  multiple  bit rates, set the bit-rate in
123              b/s. The bit-rate is the speed at  which  bits  are  transmitted
124              over  the  medium,  the  user  speed of the link is lower due to
125              medium sharing and various overhead.
126              You may append the suffix k, M or G to the value (decimal multi‐
127              plier  :  10^3,  10^6  and  10^9 b/s), or add enough '0'. Values
128              below 1000 are card specific, usually an index in  the  bit-rate
129              list.  Use  auto  to select automatic bit-rate mode (fallback to
130              lower rate on noisy channels), which is  the  default  for  most
131              cards, and fixed to revert back to fixed setting. If you specify
132              a bit-rate value and append auto, the driver will use  all  bit-
133              rates lower and equal than this value.
134              Examples :
135                   iwconfig eth0 rate 11M
136                   iwconfig eth0 rate auto
137                   iwconfig eth0 rate 5.5M auto
138
139       txpower
140              For cards supporting multiple transmit powers, sets the transmit
141              power in dBm. If W is the power in Watt, the power in dBm is P =
142              30  +  10.log(W).   If  the value is postfixed by mW, it will be
143              automatically converted to dBm.
144              In addition, on and off enable and disable the radio,  and  auto
145              and  fixed  enable  and disable power control (if those features
146              are available).
147              Examples :
148                   iwconfig eth0 txpower 15
149                   iwconfig eth0 txpower 30mW
150                   iwconfig eth0 txpower auto
151                   iwconfig eth0 txpower off
152
153       sens   Set the sensitivity threshold. This define how sensitive is  the
154              card  to  poor  operating conditions (low signal, interference).
155              Positive values are assumed to be the  raw  value  used  by  the
156              hardware or a percentage, negative values are assumed to be dBm.
157              Depending on the hardware  implementation,  this  parameter  may
158              control various functions.
159              On modern cards, this parameter usually control handover/roaming
160              threshold, the  lowest  signal  level  for  which  the  hardware
161              remains  associated with the current Access Point. When the sig‐
162              nal level goes below this threshold the card starts looking  for
163              a  new/better  Access  Point.  Some  cards may use the number of
164              missed beacons to trigger  this.  For  high  density  of  Access
165              Points,  a higher threshold make sure the card is always associ‐
166              ated with the best AP, for low density of APs, a lower threshold
167              minimise the number of failed handoffs.
168              On  more  ancient card this parameter usually controls the defer
169              threshold, the lowest signal level for which the  hardware  con‐
170              siders the channel busy. Signal levels above this threshold make
171              the hardware  inhibits  its  own  transmission  whereas  signals
172              weaker  than this are ignored and the hardware is free to trans‐
173              mit. This is usually strongly linked to the  receive  threshold,
174              the  lowest  signal level for which the hardware attempts packet
175              reception. Proper setting of these thresholds prevent  the  card
176              to  waste  time  on  background noise while still receiving weak
177              transmissions. Modern designs seems to control those  thresholds
178              automatically.
179              Example :
180                   iwconfig eth0 sens -80
181                   iwconfig eth0 sens 2
182
183       retry  Most  cards  have MAC retransmissions, and some allow to set the
184              behaviour of the retry mechanism.
185              To set the maximum number of retries, enter limit `value'.  This
186              is an absolute value (without unit), and the default (when noth‐
187              ing is specified).  To set the maximum length of  time  the  MAC
188              should  retry,  enter lifetime `value'.  By defaults, this value
189              in in seconds, append the suffix m or u  to  specify  values  in
190              milliseconds or microseconds.
191              You  can also add the short, long, min and max modifiers. If the
192              card supports automatic mode, they  define  the  bounds  of  the
193              limit  or  lifetime.  Some  other  cards define different values
194              depending on packet size, for example in 802.11 min limit is the
195              short retry limit (non RTS/CTS packets).
196              Examples :
197                   iwconfig eth0 retry 16
198                   iwconfig eth0 retry lifetime 300m
199                   iwconfig eth0 retry short 12
200                   iwconfig eth0 retry min limit 8
201
202       rts[_threshold]
203              RTS/CTS adds a handshake before each packet transmission to make
204              sure  that  the  channel  is  clear.  This  adds  overhead,  but
205              increases  performance in case of hidden nodes or a large number
206              of active nodes. This parameter sets the size  of  the  smallest
207              packet for which the node sends RTS ; a value equal to the maxi‐
208              mum packet size disables the mechanism. You may  also  set  this
209              parameter to auto, fixed or off.
210              Examples :
211                   iwconfig eth0 rts 250
212                   iwconfig eth0 rts off
213
214       frag[mentation_threshold]
215              Fragmentation allows to split an IP packet in a burst of smaller
216              fragments transmitted on the medium. In  most  cases  this  adds
217              overhead, but in a very noisy environment this reduces the error
218              penalty and allow packets to get  through  interference  bursts.
219              This  parameter  sets  the maximum fragment size which is always
220              lower than the maximum packet size.
221              This parameter may also control Frame Bursting available on some
222              cards,  the  ability  to send multiple IP packets together. This
223              mechanism would be enabled if the fragment size is  larger  than
224              the maximum packet size.
225              You may also set this parameter to auto, fixed or off.
226              Examples :
227                   iwconfig eth0 frag 512
228                   iwconfig eth0 frag off
229
230       key/enc[ryption]
231              Used  to  manipulate  encryption or scrambling keys and security
232              mode.
233              To set the current encryption key, just enter  the  key  in  hex
234              digits  as  XXXX-XXXX-XXXX-XXXX or XXXXXXXX.  To set a key other
235              than the current key, prepend  or  append  [index]  to  the  key
236              itself (this won't change which is the active key). You can also
237              enter the key as  an  ASCII  string  by  using  the  s:  prefix.
238              Passphrase is currently not supported.
239              To  change  which  key  is  the currently active key, just enter
240              [index] (without entering any key value).
241              off and on disable and reenable encryption.
242              The security mode may be open or  restricted,  and  its  meaning
243              depends  on  the  card  used.  With  most cards, in open mode no
244              authentication is  used  and  the  card  may  also  accept  non-
245              encrypted  sessions,  whereas  in restricted mode only encrypted
246              sessions are accepted and the card will  use  authentication  if
247              available.
248              If  you  need  to set multiple keys, or set a key and change the
249              active key, you need to use multiple key  directives.  Arguments
250              can be put in any order, the last one will take precedence.
251              Examples :
252                   iwconfig eth0 key 0123-4567-89
253                   iwconfig eth0 key [3] 0123-4567-89
254                   iwconfig eth0 key s:password [2]
255                   iwconfig eth0 key [2]
256                   iwconfig eth0 key open
257                   iwconfig eth0 key off
258                   iwconfig eth0 key restricted [3] 0123456789
259                   iwconfig eth0 key 01-23 key 45-67 [4] key [4]
260
261       power  Used to manipulate power management scheme parameters and mode.
262              To  set  the  period between wake ups, enter period `value'.  To
263              set the timeout  before  going  back  to  sleep,  enter  timeout
264              `value'.  To set the generic level of power saving, enter saving
265              `value'.  You can  also  add  the  min  and  max  modifiers.  By
266              default,  those  values are in seconds, append the suffix m or u
267              to specify values in milliseconds  or  microseconds.  Sometimes,
268              those values are without units (number of beacon periods, dwell,
269              percentage or similar).
270              off and on disable and reenable power management.  Finally,  you
271              may  set the power management mode to all (receive all packets),
272              unicast (receive unicast packets  only,  discard  multicast  and
273              broadcast)  and multicast (receive multicast and broadcast only,
274              discard unicast packets).
275              Examples :
276                   iwconfig eth0 power period 2
277                   iwconfig eth0 power 500m unicast
278                   iwconfig eth0 power timeout 300u all
279                   iwconfig eth0 power saving 3
280                   iwconfig eth0 power off
281                   iwconfig eth0 power min period 2 power max period 4
282
283       modu[lation]
284              Force the card to use a  specific  set  of  modulations.  Modern
285              cards support various modulations, some which are standard, such
286              as 802.11b or 802.11g, and some proprietary. This command  force
287              the  card  to only use the specific set of modulations listed on
288              the command line. This  can  be  used  to  fix  interoperability
289              issues.
290              The  list of available modulations depend on the card/driver and
291              can be  displayed  using  iwlist  modulation.   Note  that  some
292              card/driver  may  not  be  able to select each modulation listed
293              independantly, some may come as a group. You may also  set  this
294              parameter to auto let the card/driver do its best.
295              Examples :
296                   iwconfig eth0 modu 11g
297                   iwconfig eth0 modu CCK OFDMa
298                   iwconfig eth0 modu auto
299
300       commit Some  cards  may  not apply changes done through Wireless Exten‐
301              sions immediately (they may wait to  aggregate  the  changes  or
302              apply  it  only when the card is brought up via ifconfig).  This
303              command (when available) forces the card to  apply  all  pending
304              changes.
305              This  is  normally  not needed, because the card will eventually
306              apply the changes, but can be useful for debugging.
307

DISPLAY

309       For each device which supports wireless extensions, iwconfig will  dis‐
310       play  the name of the MAC protocol used (name of device for proprietary
311       protocols), the ESSID (Network Name), the NWID, the frequency (or chan‐
312       nel), the sensitivity, the mode of operation, the Access Point address,
313       the bit-rate, the  RTS  threshold,  the  fragmentation  threshold,  the
314       encryption  key  and the power management settings (depending on avail‐
315       ability).
316
317       The parameters displayed have the same meaning and values as the param‐
318       eters  you  can  set,  please refer to the previous part for a detailed
319       explanation of them.
320       Some parameters are only displayed in short/abbreviated form  (such  as
321       encryption). You may use iwlist(8) to get all the details.
322       Some  parameters have two modes (such as bitrate). If the value is pre‐
323       fixed by `=', it means that the parameter is fixed and forced  to  that
324       value, if it is prefixed by `:', the parameter is in automatic mode and
325       the current value is shown (and may change).
326
327       Access Point/Cell
328              An address equal to 00:00:00:00:00:00 means that the card failed
329              to  associate  with an Access Point (most likely a configuration
330              issue). The Access Point parameter will be shown as Cell in  ad-
331              hoc mode (for obvious reasons), but otherwise works the same.
332
333       If  /proc/net/wireless  exists, iwconfig will also display its content.
334       Note that those values will depend  on  the  driver  and  the  hardware
335       specifics, so you need to refer to your driver documentation for proper
336       interpretation of those values.
337
338       Link quality
339              Overall quality of the link. May be based on the level  of  con‐
340              tention  or  interference, the bit or frame error rate, how good
341              the received signal is, some timing  synchronisation,  or  other
342              hardware metric. This is an aggregate value, and depends totally
343              on the driver and hardware.
344
345       Signal level
346              Received signal strength (RSSI - how strong the received  signal
347              is).  May  be  arbitrary units or dBm, iwconfig uses driver meta
348              information to interpret the raw value given by  /proc/net/wire‐
349              less  and  display the proper unit or maximum value (using 8 bit
350              arithmetic). In Ad-Hoc mode,  this  may  be  undefined  and  you
351              should use iwspy.
352
353       Noise level
354              Background  noise level (when no packet is transmitted). Similar
355              comments as for Signal level.
356
357       Rx invalid nwid
358              Number of packets received with a different NWID or ESSID.  Used
359              to  detect  configuration problems or adjacent network existence
360              (on the same frequency).
361
362       Rx invalid crypt
363              Number of packets that the hardware was unable to decrypt.  This
364              can be used to detect invalid encryption settings.
365
366       Rx invalid frag
367              Number  of  packets for which the hardware was not able to prop‐
368              erly re-assemble the link layer fragments (most likely  one  was
369              missing).
370
371       Tx excessive retries
372              Number  of packets that the hardware failed to deliver. Most MAC
373              protocols will retry the packet a number of times before  giving
374              up.
375
376       Invalid misc
377              Other  packets  lost  in  relation with specific wireless opera‐
378              tions.
379
380       Missed beacon
381              Number of periodic beacons from the Cell or the Access Point  we
382              have  missed.  Beacons are sent at regular intervals to maintain
383              the cell coordination, failure to receive them usually indicates
384              that the card is out of range.
385

AUTHOR

387       Jean Tourrilhes - jt@hpl.hp.com
388

FILES

390       /proc/net/wireless
391

SEE ALSO

393       ifconfig(8), iwspy(8), iwlist(8), iwevent(8), iwpriv(8), wireless(7).
394
395
396
397wireless-tools                   30 March 2006                     IWCONFIG(8)
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