1 .\" Jean II - HPLB - 1996 => HPL - 2004
4 .TH IWCONFIG 8 "22 June 2004" "wireless-tools" "Linux Programmer's Manual"
9 iwconfig \- configure a wireless network interface
14 .BI "iwconfig [" interface ]
16 .BI "iwconfig " interface " [essid " X "] [nwid " N "] [freq " F "] [channel " C ]
18 .BI " [sens " S "] [mode " M "] [ap " A "] [nick " NN ]
20 .BI " [rate " R "] [rts " RT "] [frag " FT "] [txpower " T ]
22 .BI " [enc " E "] [key " K "] [power " P "] [retry " R ]
28 .BI "iwconfig --version"
36 but is dedicated to the wireless interfaces. It is used to set the
37 parameters of the network interface which are specific to the wireless
38 operation (for example : the frequency).
40 may also be used to display those parameters, and the wireless
41 statistics (extracted from
42 .IR /proc/net/wireless ).
44 All these parameters and statistics are device dependent. Each driver
45 will provide only some of them depending on hardware support, and the
46 range of values may change. Please refer to the man page of each
54 Set the ESSID (or Network Name - in some products it may also be
55 called Domain ID). The ESSID is used to identify cells which are part
56 of the same virtual network.
58 As opposed to the AP Address or NWID which define a single cell, the
59 ESSID defines a group of cells connected via repeaters or
60 infrastructure, where the user may roam transparently.
62 With some cards, you may disable the ESSID checking (ESSID
64 .IR off " or " any " (and " on
69 .I " iwconfig eth0 essid any"
71 .I " iwconfig eth0 essid ""My Network""
74 Set the Network ID (in some products it may also be called Domain
75 ID). As all adjacent wireless networks share the same medium, this
76 parameter is used to differenciate them (create logical colocated
77 networks) and identify nodes belonging to the same cell.
79 This parameter is only used for pre-802.11 hardware, the 802.11
80 protocol uses the ESSID and AP Address for this function.
82 With some cards, you may disable the Network ID checking (NWID
89 .I " iwconfig eth0 nwid AB34
91 .I " iwconfig eth0 nwid off"
94 Set the operating frequency or channel in the device. A value below
95 1000 indicates a channel number, a value greater than 1000 is a
96 frequency in Hz. You may append the suffix k, M or G to the value (for
97 example, "2.46G" for 2.46 GHz frequency), or add enough '0'.
99 Channels are usually numbered starting at 1, and you may use
101 to get the total number of channels, list the available frequencies,
102 and display the current frequency as a channel. Depending on
103 regulations, some frequencies/channels may not be available.
107 .I " iwconfig eth0 freq 2422000000"
109 .I " iwconfig eth0 freq 2.422G"
111 .I " iwconfig eth0 channel 3"
114 Set the sensitivity threshold. This is the lowest signal level for
115 which the hardware attempt packet reception, signals weaker than this
116 are ignored. This is used to avoid receiving background noise, so you
117 should set it according to the average noise level. Positive values
118 are assumed to be the raw value used by the hardware or a percentage,
119 negative values are assumed to be dBm.
121 With some hardware, this parameter also controls the defer threshold
122 (lowest signal level for which the hardware consider the channel busy)
123 and the handover threshold (signal level where the hardware start
124 looking for a new access point).
128 .I " iwconfig eth0 sens -80"
131 Set the operating mode of the device, which depends on the network
132 topology. The mode can be
134 (network composed of only one cell and without Access Point),
136 (node connects to a network composed of many Access Points, with roaming),
138 (the node is the synchronisation master or acts as an Access Point),
140 (the node forwards packets between other wireless nodes),
142 (the node acts as a backup master/repeater),
144 (the node acts as a passive monitor and only receives packets) or
149 .I " iwconfig eth0 mode Managed"
151 .I " iwconfig eth0 mode Ad-Hoc"
154 Force the card to register to the Access Point given by the address,
155 if it is possible. When the quality of the connection goes too low,
156 the driver may revert back to automatic mode (the card selects the
157 best Access Point in range).
161 to re-enable automatic mode without changing the current Access Point,
166 to force the card to reassociate with the currently best Access Point.
170 .I " iwconfig eth0 ap 00:60:1D:01:23:45"
172 .I " iwconfig eth0 ap any"
174 .I " iwconfig eth0 ap off"
177 Set the nickname, or the station name. Some 802.11 products do define
178 it, but this is not used as far as the protocols (MAC, IP, TCP) are
179 concerned and completely useless as far as configuration goes. Only
180 some diagnostic tools may use it.
184 .I " iwconfig eth0 nickname ""My Linux Node""
186 .BR rate / bit [rate]
187 For cards supporting multiple bit rates, set the bit-rate in b/s. The
188 bit-rate is the speed at which bits are transmitted over the medium,
189 the user speed of the link is lower due to medium sharing and
192 You may append the suffix k, M or G to the value (decimal multiplier :
193 10^3, 10^6 and 10^9 b/s), or add enough '0'. Values below 1000 are
194 card specific, usually an index in the bit-rate list. Use
196 to select automatic bit-rate mode (fallback to lower rate on noisy
197 channels), which is the default for most cards, and
199 to revert back to fixed setting. If you specify a bit-rate value and append
201 the driver will use all bit-rates lower and equal than this value.
205 .I " iwconfig eth0 rate 11M"
207 .I " iwconfig eth0 rate auto"
209 .I " iwconfig eth0 rate 5.5M auto"
212 RTS/CTS adds a handshake before each packet transmission to make sure
213 that the channel is clear. This adds overhead, but increases
214 performance in case of hidden nodes or a large number of active
215 nodes. This parameter sets the size of the smallest packet for which
216 the node sends RTS ; a value equal to the maximum packet size disable
217 the mechanism. You may also set this parameter to
218 .IR auto ", " fixed " or " off .
222 .I " iwconfig eth0 rts 250"
224 .I " iwconfig eth0 rts off"
226 .BR frag [mentation_threshold]
227 Fragmentation allows to split an IP packet in a burst of smaller
228 fragments transmitted on the medium. In most cases this adds overhead,
229 but in a very noisy environment this reduces the error penalty and
230 allow packets to get through interference bursts. This parameter sets
231 the maximum fragment size ; a value equal to the maximum packet size
232 disable the mechanism. You may also set this parameter to
233 .IR auto ", " fixed " or " off .
237 .I " iwconfig eth0 frag 512"
239 .I " iwconfig eth0 frag off"
241 .BR key / enc [ryption]
242 Used to manipulate encryption or scrambling keys and security mode.
244 To set the current encryption key, just enter the key in hex digits as
245 .IR XXXX-XXXX-XXXX-XXXX " or " XXXXXXXX .
246 To set a key other than the current key, prepend or append
248 to the key itself (this won't change which is the active key). You can
249 also enter the key as an ASCII string by using the
251 prefix. Passphrase is currently not supported.
253 To change which key is the currently active key, just enter
255 (without entering any key value).
258 disable and reenable encryption.
260 The security mode may be
264 and its meaning depends on the card used. With most cards, in
266 mode no authentication is used and the card may also accept
267 non-encrypted sessions, whereas in
269 mode only encrypted sessions are accepted and the card will use
270 authentication if available.
272 If you need to set multiple keys, or set a key and change the active
273 key, you need to use multiple
275 directives. Arguments can be put in any order, the last one will take
280 .I " iwconfig eth0 key 0123-4567-89"
282 .I " iwconfig eth0 key [3] 0123-4567-89"
284 .I " iwconfig eth0 key s:password [2]"
286 .I " iwconfig eth0 key [2]"
288 .I " iwconfig eth0 key open"
290 .I " iwconfig eth0 key off"
292 .I " iwconfig eth0 key restricted [3] 0123456789"
294 .I " iwconfig eth0 key 01-23 key 45-67 [4] key [4]"
297 Used to manipulate power management scheme parameters and mode.
299 To set the period between wake ups, enter
300 .IR "period `value'" .
301 To set the timeout before going back to sleep, enter
302 .IR "timeout `value'" .
305 modifiers. By default, those values are in seconds, append the suffix
306 m or u to specify values in milliseconds or microseconds. Sometimes,
307 those values are without units (number of beacon periods, dwell or
311 disable and reenable power management. Finally, you may set the power
314 (receive all packets),
316 (receive unicast packets only, discard multicast and broadcast) and
318 (receive multicast and broadcast only, discard unicast packets).
322 .I " iwconfig eth0 power period 2"
324 .I " iwconfig eth0 power 500m unicast"
326 .I " iwconfig eth0 power timeout 300u all"
328 .I " iwconfig eth0 power off"
330 .I " iwconfig eth0 power min period 2 power max period 4"
333 For cards supporting multiple transmit powers, set the transmit power in dBm. If
335 is the power in Watt, the power in dBm is
336 .IR "P = 30 + 10.log(W)" .
337 If the value is postfixed by
339 it will be automatically converted to dBm.
343 enable and disable the radio, and
344 .IR auto " and " fixed
345 enable and disable power control (if those features are available).
349 .I " iwconfig eth0 txpower 15"
351 .I " iwconfig eth0 txpower 30mW"
353 .I " iwconfig eth0 txpower auto"
355 .I " iwconfig eth0 txpower off"
358 Most cards have MAC retransmissions, and some allow to set the
359 behaviour of the retry mechanism.
361 To set the maximum number of retries, enter
362 .IR "limit `value'" .
363 This is an absolute value (without unit).
364 The set the maximum length of time the MAC should retry, enter
365 .IR "lifetime `value'" .
366 By defaults, this value in in seconds, append the suffix m or u to
367 specify values in milliseconds or microseconds.
371 modifiers. If the card supports automatic mode, they define the bounds
372 of the limit or lifetime. Some other cards define different values
373 depending on packet size, for example in 802.11
375 is the short retry limit (non RTS/CTS packets).
379 .I " iwconfig eth0 retry 16"
381 .I " iwconfig eth0 retry lifetime 300m"
383 .I " iwconfig eth0 retry min limit 8"
386 Some cards may not apply changes done through Wireless Extensions
387 immediately (they may wait to agregate the changes or apply it only
388 when the card is brought up via ifconfig). This command (when
389 available) forces the card to apply all pending changes.
391 This is normally not needed, because the card will eventually apply
392 the changes, but can be useful for debugging.
397 For each device which supports wireless extensions,
399 will display the name of the
401 used (name of device for proprietary protocols), the
416 .BR "RTS threshold" ", the " "fragmentation threshold" ,
421 settings (depending on availability).
423 The parameters displayed have the same meaning and values as the
424 parameter you can set, please refer to the previous part for a
425 detailed explanation of them.
427 Some parameters are only displayed in short/abreviated form (such as
428 encryption). You may use
430 to get all the details.
432 Some parameters have two modes (such as bitrate). If the value is
435 it means that the parameter is fixed and forced to that value, if it
438 the parameter is in automatic mode and the current value is shown (and
441 .BR "Access Point" / Cell
442 An address equal to 00:00:00:00:00:00 means that the card failed to
443 associate with an Access Point (most likely a configuration
446 parameter will be shown as
448 in ad-hoc mode (for obvious reasons), but otherwise works the same.
451 .I /proc/net/wireless
454 will also display its content. Note that those values will depend on
455 the driver and the hardware specifics, so you need to refer to your
456 driver documentation for proper interpretation of those values.
459 Overall quality of the link. May be based on the level of contention
460 or interference, the bit or frame error rate, how good the received
461 signal is, some timing synchronisation, or other hardware metric. This
462 is an aggregate value, and depends totally on the driver and hardware.
465 Received signal strength (RSSI - how strong the received signal
466 is). May be arbitrary units or dBm,
468 uses driver meta information to interpret the raw value given by
469 .I /proc/net/wireless
470 and display the proper unit or maximum value (using 8 bit arithmetic). In
472 mode, this may be undefined and you should use
476 Background noise level (when no packet is transmitted). Similar
481 Number of packets received with a different NWID or ESSID. Used to
482 detect configuration problems or adjacent network existence (on the
486 Number of packets that the hardware was unable to decrypt. This can be
487 used to detect invalid encryption settings.
490 Number of packets for which the hardware was not able to properly
491 re-assemble the link layer fragments (most likely one was missing).
493 .B Tx excessive retries
494 Number of packets that the hardware failed to deliver. Most MAC
495 protocols will retry the packet a number of times before giving up.
498 Other packets lost in relation with specific wireless operations.
501 Number of periodic beacons from the Cell or the Access Point we have
502 missed. Beacons are sent at regular intervals to maintain the cell
503 coordination, failure to receive them usually indicates that the card
509 Jean Tourrilhes \- jt@hpl.hp.com
514 .I /proc/net/wireless