iwconfig.8

This package contains the Wireless tools, used to manipulate the Wireless Extensions. The Wireless

.IR "lifetime `value'" .
By defaults, this value in in seconds, append the suffix m or u to
specify values in milliseconds or microseconds.
.br
You can also add the
.IR min " and " max
modifiers. If the card supports automatic mode, they define the bounds
of the limit or lifetime. Some other cards define different values
depending on packet size, for example in 802.11
.I min limit
is the short retry limit (non RTS/CTS packets).
.br
.B Examples :
.br
.I "	iwconfig eth0 retry 16"
.br
.I "	iwconfig eth0 retry lifetime 300m"
.br
.I "	iwconfig eth0 retry min limit 8"
.TP
.BR rts [_threshold]
RTS/CTS adds a handshake before each packet transmission to make sure
that the channel is clear. This adds overhead, but increases
performance in case of hidden nodes or a large number of active
nodes. This parameter sets the size of the smallest packet for which
the node sends RTS ; a value equal to the maximum packet size disables
the mechanism. You may also set this parameter to
.IR auto ", " fixed " or " off .
.br
.B Examples :
.br
.I "	iwconfig eth0 rts 250"
.br
.I "	iwconfig eth0 rts off"
.TP
.BR frag [mentation_threshold]
Fragmentation allows to split an IP packet in a burst of smaller
fragments transmitted on the medium. In most cases this adds overhead,
but in a very noisy environment this reduces the error penalty and
allow packets to get through interference bursts. This parameter sets
the maximum fragment size which is always lower than the maximum
packet size.
.br
This parameter may also control Frame Bursting available on some
cards, the ability to send multiple IP packets together. This
mechanism would be enabled if the fragment size is larger than the
maximum packet size.
.br
You may also set this parameter to
.IR auto ", " fixed " or " off .
.br
.B Examples :
.br
.I "	iwconfig eth0 frag 512"
.br
.I "	iwconfig eth0 frag off"
.TP
.BR key / enc [ryption]
Used to manipulate encryption or scrambling keys and security mode.
.br
To set the current encryption key, just enter the key in hex digits as
.IR XXXX-XXXX-XXXX-XXXX " or " XXXXXXXX .
To set a key other than the current key, prepend or append
.I [index]
to the key itself (this won't change which is the active key). You can
also enter the key as an ASCII string by using the
.I s:
prefix. Passphrase is currently not supported.
.br
To change which key is the currently active key, just enter
.I [index]
(without entering any key value).
.br
.IR off " and " on
disable and reenable encryption.
.br
The security mode may be
.I open
or
.IR restricted ,
and its meaning depends on the card used. With most cards, in
.I open
mode no authentication is used and the card may also accept
non-encrypted sessions, whereas in
.I restricted
mode only encrypted sessions are accepted and the card will use
authentication if available.
.br
If you need to set multiple keys, or set a key and change the active
key, you need to use multiple
.B key
directives. Arguments can be put in any order, the last one will take
precedence.
.br
.B Examples :
.br
.I "	iwconfig eth0 key 0123-4567-89"
.br
.I "	iwconfig eth0 key [3] 0123-4567-89"
.br
.I "	iwconfig eth0 key s:password [2]"
.br
.I "	iwconfig eth0 key [2]"
.br
.I "	iwconfig eth0 key open"
.br
.I "	iwconfig eth0 key off"
.br
.I "	iwconfig eth0 key restricted [3] 0123456789"
.br
.I "	iwconfig eth0 key 01-23 key 45-67 [4] key [4]"
.TP
.BR power
Used to manipulate power management scheme parameters and mode.
.br
To set the period between wake ups, enter
.IR "period `value'" .
To set the timeout before going back to sleep, enter
.IR "timeout `value'" .
You can also add the
.IR min " and " max
modifiers. By default, those values are in seconds, append the suffix
m or u to specify values in milliseconds or microseconds. Sometimes,
those values are without units (number of beacon periods, dwell or
similar).
.br
.IR off " and " on
disable and reenable power management. Finally, you may set the power
management mode to
.I all
(receive all packets),
.I unicast
(receive unicast packets only, discard multicast and broadcast) and
.I multicast
(receive multicast and broadcast only, discard unicast packets).
.br
.B Examples :
.br
.I "	iwconfig eth0 power period 2"
.br
.I "	iwconfig eth0 power 500m unicast"
.br
.I "	iwconfig eth0 power timeout 300u all"
.br
.I "	iwconfig eth0 power off"
.br
.I "	iwconfig eth0 power min period 2 power max period 4"
.TP
.BR commit
Some cards may not apply changes done through Wireless Extensions
immediately (they may wait to aggregate the changes or apply it only
when the card is brought up via ifconfig). This command (when
available) forces the card to apply all pending changes.
.br
This is normally not needed, because the card will eventually apply
the changes, but can be useful for debugging.
.\"
.\" DISPLAY part
.\"
.SH DISPLAY
For each device which supports wireless extensions,
.I iwconfig
will display the name of the
.B MAC protocol
used (name of device for proprietary protocols), the
.B ESSID
(Network Name), the
.BR NWID ,
the
.B frequency
(or channel), the
.BR sensitivity ,
the
.B mode
of operation, the
.B Access Point
address, the
.BR bit-rate ,
the
.BR "RTS threshold" ", the " "fragmentation threshold" ,
the
.B encryption key
and the
.B power management
settings (depending on availability).
.PP
The parameters displayed have the same meaning and values as the
parameters you can set, please refer to the previous part for a
detailed explanation of them.
.br
Some parameters are only displayed in short/abbreviated form (such as
encryption). You may use
.IR iwlist (8)
to get all the details.
.br
Some parameters have two modes (such as bitrate). If the value is
prefixed by
.RB ` = ',
it means that the parameter is fixed and forced to that value, if it
is prefixed by
.RB ` : ',
the parameter is in automatic mode and the current value is shown (and
may change).
.TP
.BR "Access Point" / Cell
An address equal to 00:00:00:00:00:00 means that the card failed to
associate with an Access Point (most likely a configuration
issue). The
.B Access Point
parameter will be shown as
.B Cell
in ad-hoc mode (for obvious reasons), but otherwise works the same.
.PP
If
.I /proc/net/wireless
exists,
.I iwconfig
will also display its content. Note that those values will depend on
the driver and the hardware specifics, so you need to refer to your
driver documentation for proper interpretation of those values.
.TP
.B Link quality
Overall quality of the link. May be based on the level of contention
or interference, the bit or frame error rate, how good the received
signal is, some timing synchronisation, or other hardware metric. This
is an aggregate value, and depends totally on the driver and hardware.
.TP
.B Signal level
Received signal strength (RSSI - how strong the received signal
is). May be arbitrary units or dBm,
.I iwconfig
uses driver meta information to interpret the raw value given by
.I /proc/net/wireless
and display the proper unit or maximum value (using 8 bit arithmetic). In
.I Ad-Hoc
mode, this may be undefined and you should use
.IR iwspy .
.TP
.B Noise level
Background noise level (when no packet is transmitted). Similar
comments as for
.BR "Signal level" .
.TP
.B Rx invalid nwid
Number of packets received with a different NWID or ESSID. Used to
detect configuration problems or adjacent network existence (on the
same frequency).
.TP
.B Rx invalid crypt
Number of packets that the hardware was unable to decrypt. This can be
used to detect invalid encryption settings.
.TP
.B Rx invalid frag
Number of packets for which the hardware was not able to properly
re-assemble the link layer fragments (most likely one was missing).
.TP
.B Tx excessive retries
Number of packets that the hardware failed to deliver. Most MAC
protocols will retry the packet a number of times before giving up.
.TP
.B Invalid misc
Other packets lost in relation with specific wireless operations.
.TP
.B Missed beacon
Number of periodic beacons from the Cell or the Access Point we have
missed. Beacons are sent at regular intervals to maintain the cell
coordination, failure to receive them usually indicates that the card
is out of range.
.\"
.\" AUTHOR part
.\"
.SH AUTHOR
Jean Tourrilhes \- [e-mail]
.\"
.\" FILES part
.\"
.SH FILES
.I /proc/net/wireless
.\"
.\" SEE ALSO part
.\"
.SH SEE ALSO
.BR ifconfig (8),
.BR iwspy (8),
.BR iwlist (8),
.BR iwevent (8),
.BR iwpriv (8),
.BR wireless (7).