NAME
wlanctl —
examine IEEE 802.11 wireless
LAN client/peer table
SYNOPSIS
wlanctl |
[-p]
interface [...] |
DESCRIPTION
Use the
wlanctl utility to print node tables from IEEE 802.11
interfaces. Use the
-a flag to print the nodes for all
interfaces, or list one or more 802.11 interfaces to select their tables for
examination. The
-p flag causes only nodes that do not have
encryption enabled to be printed. For example, to examine the node tables for
atw0, use:
wlanctl may print this node table, for example:
atw0: mac 00:02:6f:20:f6:2e bss 02:02:6f:20:f6:2e
node flags 0001<bss>
ess <netbsd>
chan 11 freq 2462MHz flags 00a0<cck,2.4GHz>
capabilities 0022<ibss,short preamble>
beacon-interval 100 TU tsft 18425852102545544165 us
rates [1.0] 2.0 5.5 11.0
assoc-id 0 assoc-failed 0 inactivity 0s
rssi 161 txseq 10 rxseq 1420
atw0: mac 00:02:2d:2e:3c:f4 bss 02:02:6f:20:f6:2e
node flags 0000
ess <netbsd>
chan 11 freq 2462MHz flags 00a0<cck,2.4GHz>
capabilities 0002<ibss>
beacon-interval 100 TU tsft 18425852105450086784 us
rates [1.0] 2.0 5.5 11.0
assoc-id 0 assoc-failed 0 inactivity 0s
rssi 159 txseq 2 rxseq 551
atw0: mac 00:02:6f:20:f6:2e bss 02:02:6f:20:f6:2e
node flags 0000
ess <netbsd>
chan 11 freq 2462MHz flags 00a0<cck,2.4GHz>
capabilities 0022<ibss,short preamble>
beacon-interval 100 TU tsft 18425852102558548069 us
rates [1.0] 2.0 5.5 6.0 9.0 11.0 12.0 18.0 24.0 36.0 48.0 54.0
assoc-id 0 assoc-failed 0 inactivity 145s
rssi 163 txseq 9 rxseq 2563
This example is taken from a network consisting of three stations running in ad
hoc mode. The key for interpreting the node print-outs follows:
- mac
- In the example node table, the first network node has MAC
number 00:02:6f:20:f6:2e.
- bss
- The first node belongs to the 802.11 network identified by
Basic Service Set Identifier (BSSID) 02:02:6f:20:f6:2e.
- node
flags
- Only three node flags, “bss”,
“sta”, and “scan”, are presently defined. The
first node is distinguished from the rest by its node flags: flag
“bss” indicates that the node represents the 802.11 network
that the interface has joined or created. The MAC number for the node is
the same as the MAC number for the interface.
- ess
- the name of the (Extended) Service Set we have joined. This
is the same as the network name set by
ifconfig(8) with the
“ssid” option.
- chan
- wlanctl prints the channel number, the
center frequency in megahertz, and the channel flags. The channel flags
indicate the frequency band (“2.4GHz” or “5GHz”),
modulation (“cck”, “gfsk”, “ofdm”,
“turbo”, and “dynamic cck-ofdm”), and operation
constraints (“passive scan”). Common combinations of band and
modulation are these:
Band |
Modulation |
Description |
2.4GHz |
cck |
11Mb/s DSSS 802.11b |
2.4GHz |
gfsk |
1-2Mb/s FHSS 802.11 |
2.4GHz |
ofdm |
54Mb/s 802.11g |
2.4GHz |
dynamic cck-ofdm |
mixed 802.11b/g network |
5GHz |
ofdm |
54Mb/s 802.11a |
5GHz |
turbo |
108Mb/s 802.11a |
- capabilities
- ad hoc-mode and AP-mode 802.11 stations advertise their
capabilities in 802.11 Beacons and Probe Responses.
wlanctl understands these capability flags:
Flag |
Description |
ess |
infrastructure (access point) network |
ibss |
ad hoc network (no access point) |
cf pollable |
TBD |
request cf poll |
TBD |
privacy |
WEP encryption |
short preamble |
reduce 802.11b overhead |
pbcc |
22Mbps ``802.11b+'' |
channel agility |
change channel for licensed services |
short slot-time |
TBD |
rsn |
TBD Real Soon Now |
dsss-ofdm |
TBD |
- beacon-interval
- In the example, beacons are sent once every 100 Time Units.
A Time Unit (TU) is 1024 microseconds (a “kilo-microsecond” or
“kus”). Thus 100 TU is about one tenth of a second.
- tsft
- 802.11 stations keep a Time Synchronization Function Timer
(TSFT) which counts up in microseconds. Ad hoc-mode stations synchronize
time with their peers. Infrastructure-mode stations synchronize time with
their access point. Power-saving stations wake and sleep at intervals
measured by the TSF Timer. The TSF Timer has a role in the coalescence of
802.11 ad hoc networks (“IBSS merges”).
- rates
- 802.11 stations indicate the bit-rates they support, in
units of 100kb/s in 802.11 Beacons, Probe Responses, and Association
Requests. wlanctl prints a station's supported bit-rates
in 1Mb/s units. A station's basic rates are flagged by an asterisk
(‘*’). The last bit-rate at which a packet was sent to the
station is enclosed by square brackets.
- assoc-id
- In an infrastructure network, the access point assigns each
client an Association Identifier which is used to indicate traffic for
power-saving stations.
- assoc-failed
- The number of times the station tried and failed to
associate with its access point. Only
- inactivity
- Seconds elapsed since a packet was last received from the
station. When this value reaches net.link.ieee80211.maxinact, the station
is eligible to be purged from the node table. See
sysctl(8).
- rssi
- Unitless Received Signal Strength Indication (RSSI). Higher
numbers indicate stronger signals. Zero is the lowest possible RSSI. On a
hostap- or adhoc-mode interface, the node with node
flag “bss” set uses rssi to
indicate the signal strength for the last packet received from a station
that does not belong to the network. On an infrastructure-mode station,
the node with node flag “bss” set
indicates the strength of packets from the access point.
- txseq
- The next 802.11 packet sent to this station will carry this
transmit sequence number. The 802.11 MAC uses the transmit sequence number
to detect duplicate packets.
- rxseq
- The last packet received from this station carried this
transmit sequence number.
SEE ALSO
sysctl(8)
HISTORY
wlanctl first appeared in
NetBSD 3.0.
AUTHORS
David Young
<
dyoung@NetBSD.org>