1 .\" Jean II - HPLB - 96
4 .TH IWCONFIG 8 "31 October 1996" "net-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 dependant. Each driver
45 will provide only some of them depending on the hardware support, and
46 the range of value may change. Please refer to the man page of each
54 Set the ESSID (or Network Name - in some products it may also called
55 Domain ID). The ESSID is used to identify cells which are part of the
58 As opposed to the NWID which defines a single cell, the ESSID defines
59 a group of cell connected via repeaters or infrastructure, where the
60 user may roam. With some card, you may disable the ESSID checking
61 (ESSID promiscuous) with
62 .IR off " or " any " (and " on
67 .I " iwconfig eth0 essid any"
69 .I " iwconfig eth0 essid ""My Network""
72 Set the Network ID (in some products it is also called Domain ID). As
73 all adjacent wireless networks share the same medium, this parameter
74 is used to differenciate them (create logical colocated networks) and
75 identify nodes belonguing to the same cell. With some card, you may
76 disable the Network ID checking (NWID promiscuous) with
82 .I " iwconfig eth0 nwid AB34
84 .I " iwconfig eth0 nwid off"
87 Set the operating frequency or channel in the device. Value below 1000
88 are the channel number, value over this is the frequency in Hz. You
89 must append the suffix k, M or G to the value (for example, "2.46G"
90 for 2.46 GHz frequency), or add enough '0'.
92 Channels are usually numbered starting at 1,
95 to get the total number of channels and list the available
96 frequencies. Depending on regulations, some frequencies/channels may
101 .I " iwconfig eth0 freq 2.422G"
103 .I " iwconfig eth0 channel 3"
106 Set the sensitivity threshold. This is the lowest signal level for
107 which we attempt a packet reception, signal lower than this are not
108 received. This is used to avoid receiving background noise, so you
109 should set it according to the average noise level. Positive values
110 are assumed to be the raw value used by the hardware or a percentage,
111 negative values are assumed to be dBm.
113 With some hardware, this parameter also control the defer threshold
114 (lowest signal level for which we consider the channel busy) and the
115 handover threshold (lowest signal level where we stay associated with
116 the current access point).
120 .I " iwconfig eth0 sens -80"
123 Set the operating mode of the device, which depends on the network
124 topology. The mode can be
126 (network composed of only one cell and without Access Point),
128 (node connects to a network composed of many Access Points, with roaming),
130 (the node is the synchronisation master or act as an Access Point),
132 (the node forward packets between other wireless nodes),
134 (the node act as a backup master/repeater),
136 (the node act as a passive monitor and only receives packets) or
141 .I " iwconfig eth0 mode Managed"
143 .I " iwconfig eth0 mode Ad-Hoc"
146 Force the card to register to the Access Point given by the address,
147 if it is possible. When the quality of the connection goes too low,
148 the driver may revert back to automatic mode (the card finds the best
149 Access Point in range).
153 to re-enable automatic mode without changing the current Access Point,
158 to force the card to reassociate with the current best Access Point.
162 .I " iwconfig eth0 ap 00:60:1D:01:23:45"
164 .I " iwconfig eth0 ap any"
166 .I " iwconfig eth0 ap off"
169 Set the nickname, or the station name. Most 802.11 products do define
170 it, but this is not used as far as the protocols (MAC, IP, TCP) are
171 concerned and completely accessory as far as configuration goes. In
172 fact only some diagnostic tools may use it.
176 .I " iwconfig eth0 nickname ""My Linux Node""
178 .BR rate / bit [rate]
179 For cards supporting multiple bit rates, set the bit-rate in b/s. The
180 bit-rate is the speed at which bits are transmitted over the medium,
181 the user speed of the link is lower due to medium sharing and
184 You must append the suffix k, M or G to the value (decimal multiplier
185 : 10^3, 10^6 and 10^9 b/s), or add enough '0'. Values below 1000 are
186 card specific, usually an index in the bit-rate list. Use
188 to select the automatic bit-rate mode (fallback to lower rate on noisy
189 channels), which is the default for most cards, and
191 to revert back to fixed setting. If you specify a bit-rate value and append
193 the driver will use all bit lower and equal than this value.
197 .I " iwconfig eth0 rate 11M"
199 .I " iwconfig eth0 rate auto"
201 .I " iwconfig eth0 rate 5.5M auto"
204 RTS/CTS adds a handshake before each packet transmission to make sure
205 that the channel is clear. This adds overhead, but increase
206 performance in case of hidden nodes or large number of active
207 nodes. This parameters set the size of the smallest packet for which
208 the node sends RTS, a value equal to the maximum packet size disable
209 the scheme. You may also set this parameter to
210 .IR auto ", " fixed " or " off .
214 .I " iwconfig eth0 rts 250"
216 .I " iwconfig eth0 rts off"
218 .BR frag [mentation_threshold]
219 Fragmentation allow to split a IP packet in a burst of smaller
220 fragments transmitted on the medium. In most cases this adds overhead,
221 but in very noisy environment this reduce the error penalty. This
222 parameter set the maximum fragment size, a value equal to the maximum
223 packet size disable the scheme. You may also set this parameter to
224 .IR auto ", " fixed " or " off .
228 .I " iwconfig eth0 frag 512"
230 .I " iwconfig eth0 frag off"
232 .BR key / enc [ryption]
233 Used to manipulate encryption or scrambling keys and encryption mode.
235 To set the current encryption key, just enter the key in hex digits as
236 .IR XXXX-XXXX-XXXX-XXXX " or " XXXXXXXX .
237 To set a key other than the current key, prepend or append
239 to the key itself (this won't change which is the active key). You can
240 also enter the key as an ASCII string by using the
242 prefix. Passphrase is currently not supported.
244 To change which key is the current active key, just enter
246 (without entering any key value).
249 disable and reenable encryption,
251 set the system in open mode (accept non-encrypted packets) and
253 discard non-encrypted packets.
255 If you need to set multiple keys, or set a key and change the active
256 key, you need to use multiple
258 directives. Arguments can be put in any order, the last one will take
263 .I " iwconfig eth0 key 0123-4567-89"
265 .I " iwconfig eth0 key s:password [2]"
267 .I " iwconfig eth0 key [2] open"
269 .I " iwconfig eth0 key off"
271 .I " iwconfig eth0 key restricted [3] 0123456789"
273 .I " iwconfig eth0 key 01-23 key 45-67 [4] key [4]"
276 Used to manipulate power management scheme parameters and mode.
278 To set the period between wake up, enter
279 .IR "period `value'" .
280 To set the timeout before going back to sleep, enter
281 .IR "timeout `value'" .
284 modifiers. By defaults, those values are in seconds, append the
285 suffix m or u to specify values un milliseconds or
286 microseconds. Sometimes, those values are without units (number of
290 disable and reenable power management. Finally, you may set the power
293 (receive all packets),
295 (receive unicast packets only, discard multicast and broadcast) and
297 (receive multicast and broadcast only, discard unicast packets).
301 .I " iwconfig eth0 power period 2"
303 .I " iwconfig eth0 power 500m unicast"
305 .I " iwconfig eth0 power timeout 300u all"
307 .I " iwconfig eth0 power off"
309 .I " iwconfig eth0 power min period 2 power max period 4"
312 For cards supporting multiple transmit powers, set the transmit power in dBm. If
314 is the power in Watt, the power in dBm is
315 .IR "P = 30 + 10.log(W)" .
316 If the value is postfixed by
318 it will be automatically converted to dBm.
322 enable and disable the radio, and
323 .IR auto " and " fixed
324 enable and disable power control (if those features are available).
328 .I " iwconfig eth0 txpower 15"
330 .I " iwconfig eth0 txpower 30mW"
332 .I " iwconfig eth0 txpower auto"
334 .I " iwconfig eth0 txpower off"
337 Most cards have MAC retransmissions, and some allow to set the
338 behaviour of the retry mechanism.
340 To set the maximum number of retries, enter
341 .IR "limit `value'" .
342 This is an absolute value (without unit).
343 The set the maximum length of time the MAC should retry, enter
344 .IR "lifetime `value'" .
345 By defaults, this value in in seconds, append the suffix m or u to
346 specify values un milliseconds or microseconds.
350 modifiers. If the card support automatic mode, they define the bounds
351 of the limit or lifetime. Some other cards define different values
352 depending on packet size, for example in 802.11
354 is the short retry limit (non RTS/CTS packets).
358 .I " iwconfig eth0 retry 16"
360 .I " iwconfig eth0 retry lifetime 300m"
362 .I " iwconfig eth0 retry min limit 8"
365 Some cards may not apply changes done through Wireless Extensions
366 immediately (they may wait to agregate the changes or apply it only
367 when the card is brought up via ifconfig). This command (when
368 available) force the card to apply all pending changes.
370 This is normally not needed, because the card will eventually apply
371 the changes, but can be usefull for debugging.
376 For each device which support wireless extensions,
378 will display the name of the
380 used (name of device for proprietary protocols), the
395 .BR "RTS threshold" ", the " "fragmentation threshold" ,
400 settings (depending on availability).
402 See above for explanations of what these parameters mean.
404 If the label for bitrate is followed by
406 it means that the parameter is fixed and forced to that value, if it
409 it is only the current value (device in normal auto mode).
412 .I /proc/net/wireless
415 will also display its content :
418 Quality of the link or the modulation (what is the level of contention
419 or interference, or how good the received signal is).
422 Received signal strength (how strong the received signal is).
425 Background noise level (when no packet is transmited).
428 Number of packets received with a different NWID. Used to detect
429 configuration problems or adjacent network existence.
432 Number of packets that the hardware was unable to decrypt.
435 Other packets lost in relation with specific wireless operations.
440 Jean Tourrilhes \- jt@hpl.hp.com
445 .I /proc/net/wireless
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