wlanctl
—
examine IEEE 802.11 wireless LAN client/peer table
wlanctl |
[-p ] interface [...] |
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.
wlanctl
first appeared in NetBSD
3.0.