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 ]
30 but is dedicated to the wireless interfaces. It is used to set the
31 parameters of the network interface which are specific to the wireless
32 operation (for example : the frequency).
34 may also be used to display those parameters, and the wireless
35 statistics (extracted from
36 .IR /proc/net/wireless ).
38 All these parameters and statistics are device dependant. Each driver
39 will provide only some of them depending on the hardware support, and
40 the range of value may change. Please refer to the man page of each
48 Set the ESSID (or Network Name - in some products it may also called
49 Domain ID). The ESSID is used to identify cells which are part of the
52 As opposed to the NWID which defines a single cell, the ESSID defines
53 a group of cell connected via repeaters or infrastructure, where the
54 user may roam. With some card, you may disable the ESSID checking
55 (ESSID promiscuous) with
56 .IR off " or " any " (and " on
61 .I " iwconfig eth0 essid any"
63 .I " iwconfig eth0 essid ""My Network""
66 Set the Network ID (in some products it is also called Domain ID). As
67 all adjacent wireless networks share the same medium, this parameter
68 is used to differenciate them (create logical colocated networks) and
69 identify nodes belonguing to the same cell. With some card, you may
70 disable the Network ID checking (NWID promiscuous) with
76 .I " iwconfig eth0 nwid AB34
78 .I " iwconfig eth0 nwid off"
81 Set the operating frequency or channel in the device. Value below 1000
82 are the channel number, value over this is the frequency in Hz. You
83 must append the suffix k, M or G to the value (for example, "2.46G"
84 for 2.46 GHz frequency), or add enough '0'.
86 Channels are usually numbered starting at 1,
89 to get the total number of channels and list the available
90 frequencies. Depending on regulations, some frequencies/channels may
95 .I " iwconfig eth0 freq 2.422G"
97 .I " iwconfig eth0 channel 3"
100 Set the sensitivity threshold. This is the lowest signal level for
101 which we attempt a packet reception, signal lower than this are not
102 received. This is used to avoid receiving background noise, so you
103 should set it according to the average noise level. Positive values
104 are assumed to be the raw value used by the hardware or a percentage,
105 negative values are assumed to be dBm.
107 With some hardware, this parameter also control the defer threshold
108 (lowest signal level for which we consider the channel busy) and the
109 handover threshold (lowest signal level where we stay associated with
110 the current access point).
114 .I " iwconfig eth0 sens -80"
117 Set the operating mode of the device, which depends on the network
118 topology. The mode can be
120 (network composed of only one cell and without Access Point),
122 (network composed of many cells, with roaming or with an Access Point),
124 (the node is the synchronisation master or act as an Access Point),
126 (the node forward packets on the air),
128 (the node act as a backup master/repeater) or
133 .I " iwconfig eth0 mode Managed"
136 Register to the Access Point given by the address, if it is
137 possible. When the quality of the connection goes too low, the driver
138 may revert back to automatic mode.
142 .I " iwconfig eth0 ap 00:60:1D:01:23:45"
145 Set the nickname, or the station name. Most 802.11 products do define
146 it, but this is not used as far as the protocols (MAC, IP, TCP) are
147 concerned and completely accessory as far as configuration goes. In
148 fact only some diagnostic tools may use it.
152 .I " iwconfig eth0 nickname ""My Linux Node""
154 .BR rate / bit [rate]
155 For cards supporting multiple bit rates, set the bit-rate in b/s. The
156 bit-rate is the speed at which bits are transmitted over the medium,
157 the user speed of the link is lower due to medium sharing and
160 You must append the suffix k, M or G to the value (decimal multiplier
161 : 10^3, 10^6 and 10^9 b/s), or add enough '0'. Values below 1000 are
162 card specific, usually an index in the bit-rate list. Use
164 to select the automatic bit-rate mode (fallback to lower rate on noisy
165 channels), which is the default for most cards, and
167 to revert back to fixed setting. If you specify a bit-rate value and append
169 the driver will use all bit lower and equal than this value.
173 .I " iwconfig eth0 rate 11M"
175 .I " iwconfig eth0 rate auto"
178 RTS/CTS adds a handshake before each packet transmission to make sure
179 that the channel is clear. This adds overhead, but increase
180 performance in case of hidden nodes or large number of active
181 nodes. This parameters set the size of the smallest packet for which
182 the node sends RTS, a value equal to the maximum packet size disable
183 the scheme. You may also set this parameter to
184 .IR auto ", " fixed " or " off .
188 .I " iwconfig eth0 rts 250"
190 .I " iwconfig eth0 rts off"
192 .BR frag [mentation_threshold]
193 Fragmentation allow to split a IP packet in a burst of smaller
194 fragments transmitted on the medium. In most cases this adds overhead,
195 but in very noisy environment this reduce the error penalty. This
196 parameter set the maximum fragment size, a value equal to the maximum
197 packet size disable the scheme. You may also set this parameter to
198 .IR auto ", " fixed " or " off .
202 .I " iwconfig eth0 frag 512"
204 .I " iwconfig eth0 frag off"
206 .BR key / enc [ryption]
207 Used to manipulate encryption or scrambling keys and encryption mode.
209 To set the current encryption key, just enter the key in hex digits as
210 .IR XXXX-XXXX-XXXX-XXXX " or " XXXXXXXX .
211 To set a key other than the current key, append
213 to the key itself. You can also enter the key as an ASCII string by
218 To change which key is the current active key, just enter
220 (without entering any key value).
223 disable and reenable encryption,
225 set the system in open mode (accept non-encrypted packets) and
227 discard non-encrypted packets.
231 .I " iwconfig eth0 key 0123-4567-89"
233 .I " iwconfig eth0 key s:password [2]"
235 .I " iwconfig eth0 key [2] open"
237 .I " iwconfig eth0 key off"
240 Used to manipulate power management scheme parameters and mode.
242 To set the period between wake up, enter
243 .IR "period `value'" .
244 To set the timeout before going back to sleep, enter
245 .IR "timeout `value'" .
248 modifiers. By defaults, those values are in seconds, append the
249 suffix m or u to specify values un milliseconds or
250 microseconds. Sometimes, those values are without units (number of
254 disable and reenable power management. Finally, you may set the power
257 (receive all packets),
259 (receive unicast packets only, discard multicast and broadcast) and
261 (receive multicast and broadcast only, discard unicast packets).
265 .I " iwconfig eth0 power period 2"
267 .I " iwconfig eth0 power 500m unicast"
269 .I " iwconfig eth0 power timeout 300u all"
271 .I " iwconfig eth0 power off"
273 .I " iwconfig eth0 power min period 2 power max period 4"
276 For cards supporting multiple transmit powers, set the transmit power in dBm. If
278 is the power in Watt, the power in dBm is
279 .IR "P = 30 + 10.log(W)" .
280 If the value is postfixed by
282 it will be automatically converted to dBm.
286 enable and disable the radio, and
287 .IR auto " and " fixed
288 enable and disable power control (if those features are available).
292 .I " iwconfig eth0 txpower 15"
294 .I " iwconfig eth0 txpower 30mW"
296 .I " iwconfig eth0 txpower auto"
298 .I " iwconfig eth0 txpower off"
301 Most cards have MAC retransmissions, and some allow to set the
302 behaviour of the retry mechanism.
304 To set the maximum number of retries, enter
305 .IR "limit `value'" .
306 This is an absolute value (without unit).
307 The set the maximum length of time the MAC should retry, enter
308 .IR "lifetime `value'" .
309 By defaults, this value in in seconds, append the suffix m or u to
310 specify values un milliseconds or microseconds.
314 modifiers. If the card support automatic mode, they define the bounds
315 of the limit or lifetime. Some other cards define different values
316 depending on packet size, for example in 802.11
318 is the short retry limit (non RTS/CTS packets).
322 .I " iwconfig eth0 retry 16"
324 .I " iwconfig eth0 retry lifetime 300m"
326 .I " iwconfig eth0 retry min limit 8"
331 For each device which support wireless extensions,
333 will display the name of the
335 used (name of device for proprietary protocols), the
350 .BR "RTS threshold" ", the " "fragmentation threshold" ,
355 settings (depending on availability).
357 See above for explanations of what these parameters mean.
359 If the label for bitrate is followed by
361 it means that the parameter is fixed and forced to that value, if it
364 it is only the current value (device in normal auto mode).
367 .I /proc/net/wireless
370 will also display its content :
373 Quality of the link or the modulation (what is the level of contention
374 or interference, or how good the received signal is).
377 Received signal strength (how strong the received signal is).
380 Background noise level (when no packet is transmited).
383 Number of packets received with a different NWID. Used to detect
384 configuration problems or adjacent network existence.
387 Number of packets that the hardware was unable to decrypt.
390 Other packets lost in relation with specific wireless operations.
395 Jean Tourrilhes \- jt@hpl.hp.com
400 .I /proc/net/wireless