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 ]
32 but is dedicated to the wireless interfaces. It is used to set the
33 parameters of the network interface which are specific to the wireless
34 operation (for example : the frequency).
36 may also be used to display those parameters, and the wireless
37 statistics (extracted from
38 .IR /proc/net/wireless ).
40 All these parameters and statistics are device dependant. Each driver
41 will provide only some of them depending on the hardware support, and
42 the range of value may change. Please refer to the man page of each
50 Set the ESSID (or Network Name - in some products it may also called
51 Domain ID). The ESSID is used to identify cells which are part of the
54 As opposed to the NWID which defines a single cell, the ESSID defines
55 a group of cell connected via repeaters or infrastructure, where the
56 user may roam. With some card, you may disable the ESSID checking
57 (ESSID promiscuous) with
58 .IR off " or " any " (and " on
63 .I " iwconfig eth0 essid any"
65 .I " iwconfig eth0 essid ""My Network""
68 Set the Network ID (in some products it is also called Domain ID). As
69 all adjacent wireless networks share the same medium, this parameter
70 is used to differenciate them (create logical colocated networks) and
71 identify nodes belonguing to the same cell. With some card, you may
72 disable the Network ID checking (NWID promiscuous) with
78 .I " iwconfig eth0 nwid AB34
80 .I " iwconfig eth0 nwid off"
83 Set the operating frequency or channel in the device. Value below 1000
84 are the channel number, value over this is the frequency in Hz. You
85 must append the suffix k, M or G to the value (for example, "2.46G"
86 for 2.46 GHz frequency), or add enough '0'.
88 Channels are usually numbered starting at 1,
91 to get the total number of channels and list the available
92 frequencies. Depending on regulations, some frequencies/channels may
97 .I " iwconfig eth0 freq 2.422G"
99 .I " iwconfig eth0 channel 3"
102 Set the sensitivity threshold. This is the lowest signal level for
103 which we attempt a packet reception, signal lower than this are not
104 received. This is used to avoid receiving background noise, so you
105 should set it according to the average noise level. Positive values
106 are assumed to be the raw value used by the hardware or a percentage,
107 negative values are assumed to be dBm.
109 With some hardware, this parameter also control the defer threshold
110 (lowest signal level for which we consider the channel busy) and the
111 handover threshold (lowest signal level where we stay associated with
112 the current access point).
116 .I " iwconfig eth0 sens -80"
119 Set the operating mode of the device, which depends on the network
120 topology. The mode can be
122 (network composed of only one cell and without Access Point),
124 (network composed of many cells, with roaming or with an Access Point),
126 (the node is the synchronisation master or act as an Access Point),
128 (the node forward packets on the air),
130 (the node act as a backup master/repeater) or
135 .I " iwconfig eth0 mode Managed"
138 Register to the Access Point given by the address, if it is
139 possible. When the quality of the connection goes too low, the driver
140 may revert back to automatic mode.
144 .I " iwconfig eth0 ap 00:60:1D:01:23:45"
147 Set the nickname, or the station name. Most 802.11 products do define
148 it, but this is not used as far as the protocols (MAC, IP, TCP) are
149 concerned and completely accessory as far as configuration goes. In
150 fact only some diagnostic tools may use it.
154 .I " iwconfig eth0 nickname ""My Linux Node""
156 .BR rate / bit [rate]
157 For cards supporting multiple bit rates, set the bit-rate in b/s. The
158 bit-rate is the speed at which bits are transmitted over the medium,
159 the user speed of the link is lower due to medium sharing and
162 You must append the suffix k, M or G to the value (decimal multiplier
163 : 10^3, 10^6 and 10^9 b/s), or add enough '0'. Values below 1000 are
164 card specific, usually an index in the bit-rate list. Use
166 to select the automatic bit-rate mode (fallback to lower rate on noisy
167 channels), which is the default for most cards, and
169 to revert back to fixed setting. If you specify a bit-rate value and append
171 the driver will use all bit lower and equal than this value.
175 .I " iwconfig eth0 rate 11M"
177 .I " iwconfig eth0 rate auto"
180 RTS/CTS adds a handshake before each packet transmission to make sure
181 that the channel is clear. This adds overhead, but increase
182 performance in case of hidden nodes or large number of active
183 nodes. This parameters set the size of the smallest packet for which
184 the node sends RTS, a value equal to the maximum packet size disable
185 the scheme. You may also set this parameter to
186 .IR auto ", " fixed " or " off .
190 .I " iwconfig eth0 rts 250"
192 .I " iwconfig eth0 rts off"
194 .BR frag [mentation_threshold]
195 Fragmentation allow to split a IP packet in a burst of smaller
196 fragments transmitted on the medium. In most cases this adds overhead,
197 but in very noisy environment this reduce the error penalty. This
198 parameter set the maximum fragment size, a value equal to the maximum
199 packet size disable the scheme. You may also set this parameter to
200 .IR auto ", " fixed " or " off .
204 .I " iwconfig eth0 frag 512"
206 .I " iwconfig eth0 frag off"
208 .BR key / enc [ryption]
209 Used to manipulate encryption or scrambling keys and encryption mode.
211 To set the current encryption key, just enter the key in hex digits as
212 .IR XXXX-XXXX-XXXX-XXXX " or " XXXXXXXX .
213 To set a key other than the current key, append
215 to the key itself. You can also enter the key as an ASCII string by
220 To change which key is the current active key, just enter
222 (without entering any key value).
225 disable and reenable encryption,
227 set the system in open mode (accept non-encrypted packets) and
229 discard non-encrypted packets.
233 .I " iwconfig eth0 key 0123-4567-89"
235 .I " iwconfig eth0 key s:password [2]"
237 .I " iwconfig eth0 key [2] open"
239 .I " iwconfig eth0 key off"
242 Used to manipulate power management scheme parameters and mode.
244 To set the period between wake up, enter
245 .IR "period `value'" .
246 To set the timeout before going back to sleep, enter
247 .IR "timeout `value'" .
250 modifiers. By defaults, those values are in seconds, append the
251 suffix m or u to specify values un milliseconds or
252 microseconds. Sometimes, those values are without units (number of
256 disable and reenable power management. Finally, you may set the power
259 (receive all packets),
261 (receive unicast packets only, discard multicast and broadcast) and
263 (receive multicast and broadcast only, discard unicast packets).
267 .I " iwconfig eth0 power period 2"
269 .I " iwconfig eth0 power 500m unicast"
271 .I " iwconfig eth0 power timeout 300u all"
273 .I " iwconfig eth0 power off"
275 .I " iwconfig eth0 power min period 2 power max period 4"
278 For cards supporting multiple transmit powers, set the transmit power in dBm. If
280 is the power in Watt, the power in dBm is
281 .IR "P = 30 + 10.log(W)" .
282 If the value is postfixed by
284 it will be automatically converted to dBm.
288 enable and disable the radio, and
289 .IR auto " and " fixed
290 enable and disable power control (if those features are available).
294 .I " iwconfig eth0 txpower 15"
296 .I " iwconfig eth0 txpower 30mW"
298 .I " iwconfig eth0 txpower auto"
300 .I " iwconfig eth0 txpower off"
303 Most cards have MAC retransmissions, and some allow to set the
304 behaviour of the retry mechanism.
306 To set the maximum number of retries, enter
307 .IR "limit `value'" .
308 This is an absolute value (without unit).
309 The set the maximum length of time the MAC should retry, enter
310 .IR "lifetime `value'" .
311 By defaults, this value in in seconds, append the suffix m or u to
312 specify values un milliseconds or microseconds.
316 modifiers. If the card support automatic mode, they define the bounds
317 of the limit or lifetime. Some other cards define different values
318 depending on packet size, for example in 802.11
320 is the short retry limit (non RTS/CTS packets).
324 .I " iwconfig eth0 retry 16"
326 .I " iwconfig eth0 retry lifetime 300m"
328 .I " iwconfig eth0 retry min limit 8"
331 Some cards may not apply changes done through Wireless Extensions
332 immediately (they may wait to agregate the changes or apply it only
333 when the card is brought up). This command (when available) force
334 the card to apply all pending changes.
336 This is normally not needed, because the card will eventually apply
337 the changes, but can be usefull for debugging.
342 For each device which support wireless extensions,
344 will display the name of the
346 used (name of device for proprietary protocols), the
361 .BR "RTS threshold" ", the " "fragmentation threshold" ,
366 settings (depending on availability).
368 See above for explanations of what these parameters mean.
370 If the label for bitrate is followed by
372 it means that the parameter is fixed and forced to that value, if it
375 it is only the current value (device in normal auto mode).
378 .I /proc/net/wireless
381 will also display its content :
384 Quality of the link or the modulation (what is the level of contention
385 or interference, or how good the received signal is).
388 Received signal strength (how strong the received signal is).
391 Background noise level (when no packet is transmited).
394 Number of packets received with a different NWID. Used to detect
395 configuration problems or adjacent network existence.
398 Number of packets that the hardware was unable to decrypt.
401 Other packets lost in relation with specific wireless operations.
406 Jean Tourrilhes \- jt@hpl.hp.com
411 .I /proc/net/wireless