IFCONFIG(8) FreeBSD System Manager's Manual IFCONFIG(8)
NAME
ifconfig -- configure network interface parameters
SYNOPSIS
ifconfig [-L] [-k] [-m] [-n] interface [create] [address_family] [address
[dest_address]] [parameters]
ifconfig interface destroy
ifconfig -a [-L] [-d] [-m] [-u] [-v] [address_family]
ifconfig -l [-d] [-u] [address_family]
ifconfig [-L] [-d] [-k] [-m] [-u] [-v] [-C]
ifconfig [-g groupname]
DESCRIPTION
The ifconfig utility is used to assign an address to a network interface
and/or configure network interface parameters. The ifconfig utility must
be used at boot time to define the network address of each interface
present on a machine; it may also be used at a later time to redefine an
interface's address or other operating parameters.
The following options are available:
address
For the DARPA-Internet family, the address is either a host name
present in the host name data base, hosts(5), or a DARPA Internet
address expressed in the Internet standard ``dot notation''.
It is also possible to use the CIDR notation (also known as the
slash notation) to include the netmask. That is, one can specify
an address like 192.168.0.1/16.
For the ``inet6'' family, it is also possible to specify the pre-
fix length using the slash notation, like ::1/128. See the
prefixlen parameter below for more information.
The link-level (``link'') address is specified as a series of
colon-separated hex digits. This can be used to e.g. set a new
MAC address on an ethernet interface, though the mechanism used
is not ethernet-specific. If the interface is already up when
this option is used, it will be briefly brought down and then
brought back up again in order to ensure that the receive filter
in the underlying ethernet hardware is properly reprogrammed.
address_family
Specify the address family which affects interpretation of the
remaining parameters. Since an interface can receive transmis-
sions in differing protocols with different naming schemes, spec-
ifying the address family is recommended. The address or proto-
col families currently supported are ``inet'', ``inet6'',
``atalk'', ``ipx'', and ``link''. The default is ``inet''.
``ether'' and ``lladdr'' are synonyms for ``link''.
dest_address
Specify the address of the correspondent on the other end of a
point to point link.
interface
This parameter is a string of the form ``name unit'', for exam-
ple, ``ed0''.
groupname
List the interfaces in the given group.
The following parameters may be set with ifconfig:
add Another name for the alias parameter. Introduced for compatibil-
ity with BSD/OS.
alias Establish an additional network address for this interface. This
is sometimes useful when changing network numbers, and one wishes
to accept packets addressed to the old interface. If the address
is on the same subnet as the first network address for this
interface, a non-conflicting netmask must be given. Usually
0xffffffff is most appropriate.
-alias Remove the network address specified. This would be used if you
incorrectly specified an alias, or it was no longer needed. If
you have incorrectly set an NS address having the side effect of
specifying the host portion, removing all NS addresses will allow
you to respecify the host portion.
anycast
(Inet6 only.) Specify that the address configured is an anycast
address. Based on the current specification, only routers may
configure anycast addresses. Anycast address will not be used as
source address of any of outgoing IPv6 packets.
arp Enable the use of the Address Resolution Protocol (arp(4)) in
mapping between network level addresses and link level addresses
(default). This is currently implemented for mapping between
DARPA Internet addresses and IEEE 802 48-bit MAC addresses (Eth-
ernet, FDDI, and Token Ring addresses).
-arp Disable the use of the Address Resolution Protocol (arp(4)).
staticarp
If the Address Resolution Protocol is enabled, the host will only
reply to requests for its addresses, and will never send any
requests.
-staticarp
If the Address Resolution Protocol is enabled, the host will per-
form normally, sending out requests and listening for replies.
broadcast
(Inet only.) Specify the address to use to represent broadcasts
to the network. The default broadcast address is the address
with a host part of all 1's.
debug Enable driver dependent debugging code; usually, this turns on
extra console error logging.
-debug Disable driver dependent debugging code.
promisc
Put interface into permanently promiscuous mode.
-promisc
Disable permanently promiscuous mode.
delete Another name for the -alias parameter.
down Mark an interface ``down''. When an interface is marked
``down'', the system will not attempt to transmit messages
through that interface. If possible, the interface will be reset
to disable reception as well. This action does not automatically
disable routes using the interface.
group group-name
Assign the interface to a ``group''. Any interface can be in
multiple groups.
Cloned interfaces are members of their interface family group by
default. For example, a PPP interface such as ppp0 is a member
of the PPP interface family group, ppp.
-group group-name
Remove the interface from the given ``group''.
eui64 (Inet6 only.) Fill interface index (lowermost 64bit of an IPv6
address) automatically.
ipdst This is used to specify an Internet host who is willing to
receive IP packets encapsulating IPX packets bound for a remote
network. An apparent point to point link is constructed, and the
address specified will be taken as the IPX address and network of
the destination.
maclabel label
If Mandatory Access Control support is enabled in the kernel, set
the MAC label to label.
media type
If the driver supports the media selection system, set the media
type of the interface to type. Some interfaces support the mutu-
ally exclusive use of one of several different physical media
connectors. For example, a 10Mbit/s Ethernet interface might
support the use of either AUI or twisted pair connectors. Set-
ting the media type to 10base5/AUI would change the currently
active connector to the AUI port. Setting it to 10baseT/UTP
would activate twisted pair. Refer to the interfaces' driver
specific documentation or man page for a complete list of the
available types.
mediaopt opts
If the driver supports the media selection system, set the speci-
fied media options on the interface. The opts argument is a
comma delimited list of options to apply to the interface. Refer
to the interfaces' driver specific man page for a complete list
of available options.
-mediaopt opts
If the driver supports the media selection system, disable the
specified media options on the interface.
mode mode
If the driver supports the media selection system, set the speci-
fied operating mode on the interface to mode. For IEEE 802.11
wireless interfaces that support multiple operating modes this
directive is used to select between 802.11a (11a), 802.11b (11b),
and 802.11g (11g) operating modes.
inst minst, instance minst
Set the media instance to minst. This is useful for devices
which have multiple physical layer interfaces (PHYs).
name name
Set the interface name to name.
rxcsum, txcsum
If the driver supports user-configurable checksum offloading,
enable receive (or transmit) checksum offloading on the inter-
face. Some drivers may not be able to enable these flags inde-
pendently of each other, so setting one may also set the other.
The driver will offload as much checksum work as it can reliably
support, the exact level of offloading varies between drivers.
-rxcsum, -txcsum
If the driver supports user-configurable checksum offloading,
disable receive (or transmit) checksum offloading on the inter-
face. These settings may not always be independent of each
other.
tso If the driver supports tcp(4) segmentation offloading, enable TSO
on the interface. Some drivers may not be able to support TSO
for ip(4) and ip6(4) packets, so they may enable only one of
them.
-tso If the driver supports tcp(4) segmentation offloading, disable
TSO on the interface. It will always disable TSO for ip(4) and
ip6(4).
lro If the driver supports tcp(4) large receive offloading, enable
LRO on the interface.
-lro If the driver supports tcp(4) large receive offloading, disable
LRO on the interface.
wol, wol_ucast, wol_mcast, wol_magic
Enable Wake On Lan (WOL) support, if available. WOL is a facil-
ity whereby a machine in a low power state may be woken in
response to a received packet. There are three types of packets
that may wake a system: ucast (directed solely to the machine's
mac address), mcast (directed to a broadcast or multicast
address), or magic (unicast or multicast frames with a ``magic
contents''). Not all devices support WOL, those that do indicate
the mechanisms they support in their capabilities. wol is a syn-
onym for enabling all available WOL mechanisms. To disable WOL
use -wol.
vlanmtu, vlanhwtag
If the driver offers user-configurable VLAN support, enable
reception of extended frames or tag processing in hardware,
respectively. Note that this must be issued on a physical inter-
face associated with vlan(4), not on a vlan(4) interface itself.
-vlanmtu, -vlanhwtag
If the driver offers user-configurable VLAN support, disable
reception of extended frames or tag processing in hardware,
respectively.
polling
Turn on polling(4) feature and disable interrupts on the inter-
face, if driver supports this mode.
-polling
Turn off polling(4) feature and enable interrupt mode on the
interface.
create Create the specified network pseudo-device. If the interface is
given without a unit number, try to create a new device with an
arbitrary unit number. If creation of an arbitrary device is
successful, the new device name is printed to standard output
unless the interface is renamed or destroyed in the same ifconfig
invocation.
destroy
Destroy the specified network pseudo-device.
plumb Another name for the create parameter. Included for Solaris com-
patibility.
unplumb
Another name for the destroy parameter. Included for Solaris
compatibility.
metric n
Set the routing metric of the interface to n, default 0. The
routing metric is used by the routing protocol (routed(8)).
Higher metrics have the effect of making a route less favorable;
metrics are counted as additional hops to the destination network
or host.
mtu n Set the maximum transmission unit of the interface to n, default
is interface specific. The MTU is used to limit the size of
packets that are transmitted on an interface. Not all interfaces
support setting the MTU, and some interfaces have range restric-
tions.
netmask mask
(Inet only.) Specify how much of the address to reserve for sub-
dividing networks into sub-networks. The mask includes the net-
work part of the local address and the subnet part, which is
taken from the host field of the address. The mask can be speci-
fied as a single hexadecimal number with a leading `0x', with a
dot-notation Internet address, or with a pseudo-network name
listed in the network table networks(5). The mask contains 1's
for the bit positions in the 32-bit address which are to be used
for the network and subnet parts, and 0's for the host part. The
mask should contain at least the standard network portion, and
the subnet field should be contiguous with the network portion.
The netmask can also be specified in CIDR notation after the
address. See the address option above for more information.
prefixlen len
(Inet6 only.) Specify that len bits are reserved for subdividing
networks into sub-networks. The len must be integer, and for
syntactical reason it must be between 0 to 128. It is almost
always 64 under the current IPv6 assignment rule. If the parame-
ter is omitted, 64 is used.
The prefix can also be specified using the slash notation after
the address. See the address option above for more information.
range netrange
Under appletalk, set the interface to respond to a netrange of
the form startnet-endnet. Appletalk uses this scheme instead of
netmasks though FreeBSD implements it internally as a set of net-
masks.
remove Another name for the -alias parameter. Introduced for compati-
bility with BSD/OS.
phase The argument following this specifies the version (phase) of the
Appletalk network attached to the interface. Values of 1 or 2
are permitted.
link[0-2]
Enable special processing of the link level of the interface.
These three options are interface specific in actual effect, how-
ever, they are in general used to select special modes of opera-
tion. An example of this is to enable SLIP compression, or to
select the connector type for some Ethernet cards. Refer to the
man page for the specific driver for more information.
-link[0-2]
Disable special processing at the link level with the specified
interface.
monitor
Put the interface in monitor mode. No packets are transmitted,
and received packets are discarded after bpf(4) processing.
-monitor
Take the interface out of monitor mode.
up Mark an interface ``up''. This may be used to enable an inter-
face after an ``ifconfig down''. It happens automatically when
setting the first address on an interface. If the interface was
reset when previously marked down, the hardware will be re-ini-
tialized.
The following parameters are specific to IEEE 802.11 wireless interfaces:
apbridge
When operating as an access point, pass packets between wireless
clients directly (default). To instead let them pass up through
the system and be forwarded using some other mechanism, use
-apbridge. Disabling the internal bridging is useful when traf-
fic is to be processed with packet filtering.
authmode mode
Set the desired authentication mode in infrastructure mode. Not
all adaptors support all modes. The set of valid modes is none,
open, shared (shared key), 8021x (IEEE 802.1x), and wpa (IEEE
WPA/WPA2/802.11i). The 8021x and wpa modes are only useful when
using an authentication service (a supplicant for client opera-
tion or an authenticator when operating as an access point).
Modes are case insensitive.
bgscan Enable background scanning when operating as a station. Back-
ground scanning is a technique whereby a station associated to an
access point will temporarily leave the channel to scan for
neighboring stations. This allows a station to maintain a cache
of nearby access points so that roaming between access points can
be done without a lengthy scan operation. Background scanning is
done only when a station is not busy and any outbound traffic
will cancel a scan operation. Background scanning should never
cause packets to be lost though there may be some small latency
if outbound traffic interrupts a scan operation. By default
background scanning is enabled if the device is capable. To dis-
able background scanning, use -bgscan. Background scanning is
controlled by the bgscanidle and bgscanintvl parameters. Back-
ground scanning must be enabled for roaming; this is an artifact
of the current implementation and may not be required in the
future.
bgscanidle idletime
Set the minimum time a station must be idle (not transmitting or
receiving frames) before a background scan is initiated. The
idletime parameter is specified in milliseconds. By default a
station must be idle at least 250 milliseconds before a back-
ground scan is initiated. The idle time may not be set to less
than 100 milliseconds.
bgscanintvl interval
Set the interval at which background scanning is attempted. The
interval parameter is specified in seconds. By default a back-
ground scan is considered every 300 seconds (5 minutes). The
interval may not be set to less than 15 seconds.
bintval interval
Set the interval at which beacon frames are sent when operating
in ad-hoc or ap mode. The interval parameter is specified in
TU's (1024 usecs). By default beacon frames are transmitted
every 100 TU's.
bmissthreshold count
Set the number of consecutive missed beacons at which the station
will attempt to roam (i.e., search for a new access point). The
count parameter must be in the range 1 to 255; though the upper
bound may be reduced according to device capabilities. The
default threshold is 7 consecutive missed beacons; but this may
be overridden by the device driver. Another name for the
bmissthreshold parameter is bmiss.
bssid address
Specify the MAC address of the access point to use when operating
as a station in a BSS network. This overrides any automatic
selection done by the system. To disable a previously selected
access point, supply any, none, or - for the address. This
option is useful when more than one access point uses the same
SSID. Another name for the bssid parameter is ap.
burst Enable packet bursting. Packet bursting is a transmission tech-
nique whereby the wireless medium is acquired once to send multi-
ple frames and the interframe spacing is reduced. This technique
can significantly increase throughput by reducing transmission
overhead. Packet bursting is supported by the 802.11e QoS speci-
fication and some devices that do not support QoS may still be
capable. By default packet bursting is enabled if a device is
capable of doing it. To disable packet bursting, use -burst.
chanlist channels
Set the desired channels to use when scanning for access points,
neighbors in an IBSS network, or looking for unoccupied channels
when operating as an access point. The set of channels is speci-
fied as a comma-separated list with each element in the list rep-
resenting either a single channel number or a range of the form
``a-b''. Channel numbers must be in the range 1 to 255 and be
permissible according to the operating characteristics of the
device.
channel number
Set a single desired channel. Channels range from 1 to 255, but
the exact selection available depends on the region your adaptor
was manufactured for. Setting the channel to 0, any, or - will
give you the default for your adaptor. Some adaptors ignore this
setting unless you are in ad-hoc mode. Alternatively the fre-
quency, in megahertz, may be specified instead of the channel
number.
When there are several ways to use a channel the channel num-
ber/frequency may be appended with attributes to clarify. For
example, if a device is capable of operating on channel 6 with
802.11n and 802.11g then one can specify that g-only use should
be used by specifying ``6:g''. Similarly the channel width can
be specified by appending it with ``/''; e.g. ``6/40'' specifies
a 40MHz wide channel, These attributes can be combined as in:
``6:ht/40''. The full set of flags specified following a `:''
are: a (802.11a), b (802.11b), d (Atheros Dynamic Turbo mode), g
(802.11g), h or n (802.11n aka HT), s (Atheros Static Turbo
mode), and t (Atheros Dynamic Turbo mode, or appended to ``st''
and ``dt''). The full set of channel widths following a '/' are:
5 (5MHz aka quarter-rate channel), 10 (10MHz aka half-rate chan-
nel), 20 (20MHz mostly for use in specifying ht20), and 40 (40MHz
mostly for use in specifying ht40), In addition, a 40MHz HT chan-
nel specification may include the location of the extension chan-
nel by appending ``+'' or ``-'' for above and below, respec-
tively; e.g. ``2437:ht/40+'' specifies 40MHz wide HT operation
with the center channel at frequency 2437 and the extension chan-
nel above.
doth Enable inclusion of an 802.11h country information element in
beacon frames transmitted when operating as an access point. By
default 802.11h is enabled if the device is capable. To disable
802.11h use -doth.
deftxkey index
Set the default key to use for transmission. Typically this is
only set when using WEP encryption. Note that you must set a
default transmit key for the system to know which key to use in
encrypting outbound traffic. The weptxkey is an alias for this
request; it is provided for backwards compatibility.
dtimperiod period
Set the DTIM period for transmitting buffered multicast data
frames when operating in ap mode. The period specifies the num-
ber of beacon intervals between DTIM and must be in the range 1
to 15. By default DTIM is 1 (i.e., DTIM occurs at each beacon).
dturbo Enable the use of Atheros Dynamic Turbo mode when communicating
with another Dynamic Turbo-capable station. Dynamic Turbo mode
is an Atheros-specific mechanism by which stations switch between
normal 802.11 operation and a ``boosted'' mode in which a 40MHz
wide channel is used for communication. Stations using Dynamic
Turbo mode operate boosted only when the channel is free of non-
dturbo stations; when a non-dturbo station is identified on the
channel all stations will automatically drop back to normal oper-
ation. By default, Dynamic Turbo mode is not enabled, even if
the device is capable. Note that turbo mode (dynamic or static)
is only allowed on some channels depending on the regulatory con-
straints; use the list chan command to identify the channels
where turbo mode may be used. To disable Dynamic Turbo mode use
-dturbo.
fragthreshold length
Set the threshold for which transmitted frames are broken into
fragments. The length argument is the frame size in bytes and
must be in the range 256 to 2346. Setting length to 2346, any,
or - disables transmit fragmentation. Not all adaptors honor the
fragmentation threshold.
hidessid
When operating as an access point, do not broadcast the SSID in
beacon frames or respond to probe request frames unless they are
directed to the ap (i.e., they include the ap's SSID). By
default, the SSID is included in beacon frames and undirected
probe request frames are answered. To re-enable the broadcast of
the SSID etc., use -hidessid.
ff Enable the use of Atheros Fast Frames when communicating with
another Fast Frames-capable station. Fast Frames are an encapsu-
lation technique by which two 802.3 frames are transmitted in a
single 802.11 frame. This can noticeably improve throughput but
requires that the receiving station understand how to decapsulate
the frame. Fast frame use is negotiated using the Atheros 802.11
vendor-specific protocol extension so enabling use is safe when
communicating with non-Atheros devices. By default, use of fast
frames is enabled if the device is capable. To explicitly dis-
able fast frames, use -ff.
list active
Display the list of channels available for use taking into
account any restrictions set with the chanlist directive. See
the description of list chan for more information.
list caps
Display the adaptor's capabilities, including the operating modes
supported.
list chan
Display the list of channels available for use. Channels are
shown with their IEEE channel number, equivalent frequency, and
usage modes. Channels identified as `11g' are also usable in
`11b' mode. Channels identified as `11a Turbo' may be used only
for Atheros' Static Turbo mode (specified with mediaopt turbo).
Channels marked with a `*' have a regulatory constraint that they
be passively scanned. This means a station is not permitted to
transmit on the channel until it identifies the channel is being
used for 802.11 communication; typically by hearing a beacon
frame from an access point operating on the channel. list freq
is another way of requesting this information. By default a com-
pacted list of channels is displayed; if the -v option is speci-
fied then all channels are shown.
list mac
Display the current MAC Access Control List state. Each address
is prefixed with a character that indicates the current policy
applied to it: `+' indicates the address is allowed access, `-'
indicates the address is denied access, `*' indicates the address
is present but the current policy open (so the ACL is not con-
sulted).
list scan
Display the access points and/or ad-hoc neighbors located in the
vicinity. The -v flag may be used to display long SSIDs. -v
also causes received information elements to be displayed symbol-
ically. This information may be updated automatically by the
adaptor and/or with a scan request or through background scan-
ning. The list ap command is another way of requesting this
information.
list sta
When operating as an access point display the stations that are
currently associated. When operating in ad-hoc mode display sta-
tions identified as neighbors in the IBSS. When operating in
station mode display the access point. Capabilities advertised
by the stations are described under the scan request. Depending
on the capabilities of the stations the following flags can be
included in the output:
A Authorized. Indicates that the station is permitted to
send/receive data frames.
E Extended Rate Phy (ERP). Indicates that the station is
operating in an 802.11g network using extended transmit
rates.
H High Throughput (HT). Indicates that the station is using
MCS to send/receive frames.
P Power Save. Indicates that the station is operating in
power save mode.
Q Quality of Service (QoS). Indicates that the station is
using QoS encapsulation for data frame. QoS encapsulation
is enabled only when WME mode is enabled.
By default information elements received from associated stations
are displayed in a short form; the -v flag causes this informa-
tion to be displayed symbolically.
list wme
Display the current parameters to use when operating in WME mode.
When WME mode is enabled for an adaptor this information will be
displayed with the regular status; this command is mostly useful
for examining parameters when WME mode is disabled. See the
description of the wme directive for information on the various
parameters.
mcastrate rate
Set the rate for transmitting multicast/broadcast frames. Rates
are specified as megabits/second in decimal; e.g. 5.5 for 5.5
Mb/s. This rate should be valid for the current operating condi-
tions; if an invalid rate is specified drivers are free to chose
an appropriate rate.
powersave
Enable powersave operation. When operating as a client, the sta-
tion will conserve power by periodically turning off the radio
and listening for messages from the access point telling it there
are packets waiting. The station must then retrieve the packets.
Not all devices support power save operation as a client. The
802.11 specification requires that all access points support
power save but some drivers do not. Use -powersave to disable
powersave operation when operating as a client.
powersavesleep sleep
Set the desired max powersave sleep time in TU's (1024 usecs).
By default the max powersave sleep time is 100 TU's.
protmode technique
For interfaces operating in 802.11g, use the specified technique
for protecting OFDM frames in a mixed 11b/11g network. The set
of valid techniques is off, cts (CTS to self), and rtscts
(RTS/CTS). Technique names are case insensitive. Not all
devices support cts as a protection technique.
pureg When operating as an access point in 802.11g mode allow only 11g-
capable stations to associate (11b-only stations are not permit-
ted to associate). To allow both 11g and 11b-only stations to
associate, use -pureg.
roaming mode
When operating as a station, control how the system will behave
when communication with the current access point is broken. The
mode argument may be one of device (leave it to the hardware
device to decide), auto (handle either in the device or the oper-
ating system--as appropriate), manual (do nothing until explic-
itly instructed). By default, the device is left to handle this
if it is capable; otherwise, the operating system will automati-
cally attempt to reestablish communication. Manual mode is used
by applications such as wpa_supplicant(8) that want to control
the selection of an access point.
roam:rssi11a rssi
Set the threshold for controlling roaming when operating in an
802.11a BSS. The rssi parameter specifies the receive signal
strength in dBm units at which roaming should be considered. If
the current rssi drops below this setting and background scanning
is enabled, then the system will check if a more desirable access
point is available and switch over to it. The current scan cache
contents are used if they are considered valid according to the
scanvalid parameter; otherwise a background scan operation is
triggered before any selection occurs. By default rssi is set to
7 dBm.
roam:rssi11b rssi
Set the threshold for controlling roaming when operating in an
802.11b-only BSS. See roam:rssi11a for a description of this
parameter. By default rssi is set to 7 dBm.
roam:rssi11g rssi
Set the threshold for controlling roaming when operating in a
(mixed) 802.11g BSS. See roam:rssi11a for a description of this
parameter. By default rssi is set to 7 dBm.
roam:rate11a rate
Set the threshold for controlling roaming when operating in an
802.11a BSS. The rate parameter specifies the transmit rate in
megabits at which roaming should be considered. If the current
transmit rate drops below this setting and background scanning is
enabled, then the system will check if a more desirable access
point is available and switch over to it. The current scan cache
contents are used if they are considered valid according to the
scanvalid parameter; otherwise a background scan operation is
triggered before any selection occurs. By default rate is set to
12 Mb/s.
roam:rate11b rate
Set the threshold for controlling roaming when operating in an
802.11b-only BSS. See roam:rate11a for a description of this
parameter. By default rate is set to 1 Mb/s.
roam:rate11g rate
Set the threshold for controlling roaming when operating in a
(mixed) 802.11g BSS. See roam:rate11a for a description of this
parameter. By default rate is set to 5 Mb/s.
rtsthreshold length
Set the threshold for which transmitted frames are preceded by
transmission of an RTS control frame. The length argument is the
frame size in bytes and must be in the range 1 to 2346. Setting
length to 2346, any, or - disables transmission of RTS frames.
Not all adaptors support setting the RTS threshold.
ssid ssid
Set the desired Service Set Identifier (aka network name). The
SSID is a string up to 32 characters in length and may be speci-
fied as either a normal string or in hexadecimal when preceded by
`0x'. Additionally, the SSID may be cleared by setting it to
`-'.
scan Initiate a scan of neighboring stations, wait for it to complete,
and display all stations found. Only the super-user can initiate
a scan. Depending on the capabilities of the APs, the following
flags can be included in the output:
A Channel Agility. Indicates that the station support channel
hopping as described by the IEEE 802.11b specification.
B Packet Binary Convolution Code (PBCC). A modulation alter-
native to the standard OFDM method.
C Pollreq
c Pollable
D Direct Sequence Spread Spectrum (DSSSOFDM). Indicates the
the station supports DSSS modulation.
E Extended Service Set (ESS). Indicates that the station is
part of an infrastructure network (in contrast to an
IBSS/ad-hoc network).
I IBSS/ad-hoc network. Indicates that the station is part of
an ad-hoc network (in contrast to an ESS network).
P Privacy. Data confidentiality is required for all data
frames exchanged within the BSS. This means that this BSS
requires the station to use cryptographic means such as WEP,
TKIP or AES-CCMP to encrypt/decrypt data frames being
exchanged with others.
R Robust Security Network (RSN). Indicates that the station
supports the IEEE 802.11i authentication and key management
protocol.
S Short Preamble. Indicates that the network is using short
preambles (defined in 802.11b High Rate/DSSS PHY, short pre-
amble utilizes a 56 bit sync field in contrast to a 128 bit
field used in long preamble mode).
s Short slot time. Indicates that the network is using a
short slot time.
Interesting information elements captured from the neighboring
stations are displayed at the end of each row. Possible elements
are: WME (station supports WME), WPA (station supports WPA), WPS
(station supports WPS), RSN (station supports 802.11i/RSN), HT
(station supports 802.11n/HT communication), ATH (station sup-
ports Atheros protocol extensions), VEN (station supports unknown
vendor-specific extensions). If the -v flag is used the informa-
tion element contents will be shown.
The list scan request can be used to show recent scan results
without initiating a new scan.
The -v flag may be used to prevent the shortening of long SSIDs.
scanvalid threshold
Set the maximum time the scan cache contents are considered
valid; i.e. will be used without first triggering a scan opera-
tion to refresh the data. The threshold parameter is specified
in seconds and defaults to 60 seconds. The minimum setting for
threshold is 10 seconds. One should take care setting this
threshold; if it is set too low then attempts to roam to another
access point may trigger unnecessary background scan operations.
stationname name
Set the name of this station. The station name is not part of
the IEEE 802.11 protocol though some interfaces support it. As
such it only seems to be meaningful to identical or virtually
identical equipment. Setting the station name is identical in
syntax to setting the SSID.
txpower power
Set the power used to transmit frames. The power argument is
specified in .5 dBm units. Out of range values are truncated.
Typically only a few discreet power settings are available and
the driver will use the setting closest to the specified value.
Not all adaptors support changing the transmit power.
wepmode mode
Set the desired WEP mode. Not all adaptors support all modes.
The set of valid modes is off, on, and mixed. The mixed mode
explicitly tells the adaptor to allow association with access
points which allow both encrypted and unencrypted traffic. On
these adaptors, on means that the access point must only allow
encrypted connections. On other adaptors, on is generally
another name for mixed. Modes are case insensitive.
weptxkey index
Set the WEP key to be used for transmission. This is the same as
setting the default transmission key with deftxkey.
wepkey key|index:key
Set the selected WEP key. If an index is not given, key 1 is
set. A WEP key will be either 5 or 13 characters (40 or 104
bits) depending of the local network and the capabilities of the
adaptor. It may be specified either as a plain string or as a
string of hexadecimal digits preceded by `0x'. For maximum
portability, hex keys are recommended; the mapping of text keys
to WEP encryption is usually driver-specific. In particular, the
Windows drivers do this mapping differently to FreeBSD. A key
may be cleared by setting it to `-'. If WEP is supported then
there are at least four keys. Some adaptors support more than
four keys. If that is the case, then the first four keys (1-4)
will be the standard temporary keys and any others will be adap-
tor specific keys such as permanent keys stored in NVRAM.
Note that you must set a default transmit key with deftxkey for
the system to know which key to use in encrypting outbound traf-
fic.
wme Enable Wireless Multimedia Extensions (WME) support, if avail-
able, for the specified interface. WME is a subset of the IEEE
802.11e standard to support the efficient communication of real-
time and multimedia data. To disable WME support, use -wme.
The following parameters are meaningful only when WME support is
in use. Parameters are specified per-AC (Access Category) and
split into those that are used by a station when acting as an
access point and those for client stations in the BSS. The lat-
ter are received from the access point and may not be changed (at
the station). The following Access Categories are recognized:
AC_BE (or BE) best effort delivery,
AC_BK (or BK) background traffic,
AC_VI (or VI) video traffic,
AC_VO (or VO) voice traffic.
AC parameters are case-insensitive. Traffic classification is
done in the operating system using the vlan priority associated
with data frames or the ToS (Type of Service) indication in IP-
encapsulated frames. If neither information is present, traffic
is assigned to the Best Effort (BE) category.
ack ac Set the ACK policy for QoS transmissions by the local
station; this controls whether or not data frames trans-
mitted by a station require an ACK response from the
receiving station. To disable waiting for an ACK use
-ack. This parameter is applied only to the local sta-
tion.
acm ac Enable the Admission Control Mandatory (ACM) mechanism
for transmissions by the local station. To disable the
ACM use -acm. On stations in a BSS this parameter is
read-only and indicates the setting received from the
access point. NB: ACM is not supported right now.
aifs ac count
Set the Arbitration Inter Frame Spacing (AIFS) channel
access parameter to use for transmissions by the local
station. On stations in a BSS this parameter is read-
only and indicates the setting received from the access
point.
cwmin ac count
Set the CWmin channel access parameter to use for trans-
missions by the local station. On stations in a BSS this
parameter is read-only and indicates the setting received
from the access point.
cwmax ac count
Set the CWmax channel access parameter to use for trans-
missions by the local station. On stations in a BSS this
parameter is read-only and indicates the setting received
from the access point.
txoplimit ac limit
Set the Transmission Opportunity Limit channel access
parameter to use for transmissions by the local station.
This parameter defines an interval of time when a WME
station has the right to initiate transmissions onto the
wireless medium. On stations in a BSS this parameter is
read-only and indicates the setting received from the
access point.
bss:aifs ac count
Set the AIFS channel access parameter to send to stations
in a BSS. This parameter is meaningful only when operat-
ing in ap mode.
bss:cwmin ac count
Set the CWmin channel access parameter to send to sta-
tions in a BSS. This parameter is meaningful only when
operating in ap mode.
bss:cwmax ac count
Set the CWmax channel access parameter to send to sta-
tions in a BSS. This parameter is meaningful only when
operating in ap mode.
bss:txoplimit ac limit
Set the TxOpLimit channel access parameter to send to
stations in a BSS. This parameter is meaningful only
when operating in ap mode.
The following parameters support an optional access control list feature
available with some adaptors when operating in ap mode; see wlan_acl(4).
This facility allows an access point to accept/deny association requests
based on the MAC address of the station. Note that this feature does not
significantly enhance security as MAC address spoofing is easy to do.
mac:add address
Add the specified MAC address to the database. Depending on the
policy setting association requests from the specified station
will be allowed or denied.
mac:allow
Set the ACL policy to permit association only by stations regis-
tered in the database.
mac:del address
Delete the specified MAC address from the database.
mac:deny
Set the ACL policy to deny association only by stations regis-
tered in the database.
mac:kick address
Force the specified station to be deauthenticated. This typi-
cally is done to block a station after updating the address data-
base.
mac:open
Set the ACL policy to allow all stations to associate.
mac:flush
Delete all entries in the database.
The following parameters are for compatibility with other systems:
nwid ssid
Another name for the ssid parameter. Included for NetBSD compat-
ibility.
station name
Another name for the stationname parameter. Included for BSD/OS
compatibility.
wep Another way of saying wepmode on. Included for BSD/OS compati-
bility.
-wep Another way of saying wepmode off. Included for BSD/OS compati-
bility.
nwkey key
Another way of saying: ``wepmode on weptxkey 1 wepkey 1:key
wepkey 2:- wepkey 3:- wepkey 4:-''. Included for NetBSD compati-
bility.
nwkey n:k1,k2,k3,k4
Another way of saying ``wepmode on weptxkey n wepkey 1:k1 wepkey
2:k2 wepkey 3:k3 wepkey 4:k4''. Included for NetBSD compatibil-
ity.
-nwkey Another way of saying wepmode off. Included for NetBSD compati-
bility.
The following parameters are specific to bridge interfaces:
addm interface
Add the interface named by interface as a member of the bridge.
The interface is put into promiscuous mode so that it can receive
every packet sent on the network.
deletem interface
Remove the interface named by interface from the bridge. Promis-
cuous mode is disabled on the interface when it is removed from
the bridge.
maxaddr size
Set the size of the bridge address cache to size. The default is
100 entries.
timeout seconds
Set the timeout of address cache entries to seconds seconds. If
seconds is zero, then address cache entries will not be expired.
The default is 240 seconds.
addr Display the addresses that have been learned by the bridge.
static interface-name address
Add a static entry into the address cache pointing to
interface-name. Static entries are never aged out of the cache
or re-placed, even if the address is seen on a different inter-
face.
deladdr address
Delete address from the address cache.
flush Delete all dynamically-learned addresses from the address cache.
flushall
Delete all addresses, including static addresses, from the
address cache.
discover interface
Mark an interface as a ``discovering'' interface. When the
bridge has no address cache entry (either dynamic or static) for
the destination address of a packet, the bridge will forward the
packet to all member interfaces marked as ``discovering''. This
is the default for all interfaces added to a bridge.
-discover interface
Clear the ``discovering'' attribute on a member interface. For
packets without the ``discovering'' attribute, the only packets
forwarded on the interface are broadcast or multicast packets and
packets for which the destination address is known to be on the
interface's segment.
learn interface
Mark an interface as a ``learning'' interface. When a packet
arrives on such an interface, the source address of the packet is
entered into the address cache as being a destination address on
the interface's segment. This is the default for all interfaces
added to a bridge.
-learn interface
Clear the ``learning'' attribute on a member interface.
sticky interface
Mark an interface as a ``sticky'' interface. Dynamically learned
address entries are treated at static once entered into the
cache. Sticky entries are never aged out of the cache or
replaced, even if the address is seen on a different interface.
-sticky interface
Clear the ``sticky'' attribute on a member interface.
private interface
Mark an interface as a ``private'' interface. A private inter-
face does not forward any traffic to any other port that is also
a private interface.
-private interface
Clear the ``private'' attribute on a member interface.
span interface
Add the interface named by interface as a span port on the
bridge. Span ports transmit a copy of every frame received by
the bridge. This is most useful for snooping a bridged network
passively on another host connected to one of the span ports of
the bridge.
-span interface
Delete the interface named by interface from the list of span
ports of the bridge.
stp interface
Enable Spanning Tree protocol on interface. The if_bridge(4)
driver has support for the IEEE 802.1D Spanning Tree protocol
(STP). Spanning Tree is used to detect and remove loops in a
network topology.
-stp interface
Disable Spanning Tree protocol on interface. This is the default
for all interfaces added to a bridge.
edge interface
Set interface as an edge port. An edge port connects directly to
end stations cannot create bridging loops in the network, this
allows it to transition straight to forwarding.
-edge interface
Disable edge status on interface.
autoedge interface
Allow interface to automatically detect edge status. This is the
default for all interfaces added to a bridge.
-autoedge interface
Disable automatic edge status on interface.
ptp interface
Set the interface as a point to point link. This is required for
straight transitions to forwarding and should be enabled on a
direct link to another RSTP capable switch.
-ptp interface
Disable point to point link status on interface. This should be
disabled for a half duplex link and for an interface connected to
a shared network segment, like a hub or a wireless network.
autoptp interface
Automatically detect the point to point status on interface by
checking the full duplex link status. This is the default for
interfaces added to the bridge.
-autoptp interface
Disable automatic point to point link detection on interface.
maxage seconds
Set the time that a Spanning Tree protocol configuration is
valid. The default is 20 seconds. The minimum is 6 seconds and
the maximum is 40 seconds.
fwddelay seconds
Set the time that must pass before an interface begins forwarding
packets when Spanning Tree is enabled. The default is 15 sec-
onds. The minimum is 4 seconds and the maximum is 30 seconds.
hellotime seconds
Set the time between broadcasting of Spanning Tree protocol con-
figuration messages. The hello time may only be changed when
operating in legacy stp mode. The default is 2 seconds. The
minimum is 1 second and the maximum is 2 seconds.
priority value
Set the bridge priority for Spanning Tree. The default is 32768.
The minimum is 0 and the maximum is 61440.
proto value
Set the Spanning Tree protocol. The default is rstp. The avail-
able options are stp and rstp.
holdcnt value
Set the transmit hold count for Spanning Tree. This is the num-
ber of packets transmitted before being rate limited. The
default is 6. The minimum is 1 and the maximum is 10.
ifpriority interface value
Set the Spanning Tree priority of interface to value. The
default is 128. The minimum is 0 and the maximum is 240.
ifpathcost interface value
Set the Spanning Tree path cost of interface to value. The
default is calculated from the link speed. To change a previ-
ously selected path cost back to automatic, set the cost to 0.
The minimum is 1 and the maximum is 200000000.
ifmaxaddr interface size
Set the maximum number of hosts allowed from an interface, pack-
ets with unknown source addresses are dropped until an existing
host cache entry expires or is removed. Set to 0 to disable.
The following parameters are specific to lagg interfaces:
laggport interface
Add the interface named by interface as a port of the aggregation
interface.
-laggport interface
Remove the interface named by interface from the aggregation
interface.
laggproto proto
Set the aggregation protocol. The default is failover. The
available options are failover, fec, lacp, loadbalance,
roundrobin and none.
The following parameters are specific to IP tunnel interfaces, gif(4):
tunnel src_addr dest_addr
Configure the physical source and destination address for IP tun-
nel interfaces. The arguments src_addr and dest_addr are inter-
preted as the outer source/destination for the encapsulating
IPv4/IPv6 header.
-tunnel
Unconfigure the physical source and destination address for IP
tunnel interfaces previously configured with tunnel.
deletetunnel
Another name for the -tunnel parameter.
The following parameters are specific to GRE tunnel interfaces, gre(4):
grekey key
Configure the GRE key to be used for outgoing packets. Note that
gre(4) will always accept GRE packets with invalid or absent
keys. This command will result in a four byte MTU reduction on
the interface.
The following parameters are specific to pfsync(4) interfaces:
maxupd n
Set the maximum number of updates for a single state which can be
collapsed into one. This is an 8-bit number; the default value
is 128.
The following parameters are specific to vlan(4) interfaces:
vlan vlan_tag
Set the VLAN tag value to vlan_tag. This value is a 16-bit num-
ber which is used to create an 802.1Q VLAN header for packets
sent from the vlan(4) interface. Note that vlan and vlandev must
both be set at the same time.
vlandev iface
Associate the physical interface iface with a vlan(4) interface.
Packets transmitted through the vlan(4) interface will be
diverted to the specified physical interface iface with 802.1Q
VLAN encapsulation. Packets with 802.1Q encapsulation received
by the parent interface with the correct VLAN tag will be
diverted to the associated vlan(4) pseudo-interface. The vlan(4)
interface is assigned a copy of the parent interface's flags and
the parent's ethernet address. The vlandev and vlan must both be
set at the same time. If the vlan(4) interface already has a
physical interface associated with it, this command will fail.
To change the association to another physical interface, the
existing association must be cleared first.
Note: if the hardware tagging capability is set on the parent
interface, the vlan(4) pseudo interface's behavior changes: the
vlan(4) interface recognizes that the parent interface supports
insertion and extraction of VLAN tags on its own (usually in
firmware) and that it should pass packets to and from the parent
unaltered.
-vlandev [iface]
If the driver is a vlan(4) pseudo device, disassociate the parent
interface from it. This breaks the link between the vlan(4)
interface and its parent, clears its VLAN tag, flags and its link
address and shuts the interface down. The iface argument is use-
less and hence deprecated.
The following parameters are specific to carp(4) interfaces:
advbase seconds
Specifies the base of the advertisement interval in seconds. The
acceptable values are 1 to 255. The default value is 1.
advskew interval
Specifies the skew to add to the base advertisement interval to
make one host advertise slower than another host. It is speci-
fied in 1/256 of seconds. The acceptable values are 1 to 254.
The default value is 0.
pass phrase
Set the authentication key to phrase.
vhid n Set the virtual host ID. This is a required setting. Acceptable
values are 1 to 255.
The ifconfig utility displays the current configuration for a network
interface when no optional parameters are supplied. If a protocol family
is specified, ifconfig will report only the details specific to that pro-
tocol family.
If the -m flag is passed before an interface name, ifconfig will display
the capability list and all of the supported media for the specified
interface. If -L flag is supplied, address lifetime is displayed for
IPv6 addresses, as time offset string.
Optionally, the -a flag may be used instead of an interface name. This
flag instructs ifconfig to display information about all interfaces in
the system. The -d flag limits this to interfaces that are down, and -u
limits this to interfaces that are up. When no arguments are given, -a
is implied.
The -l flag may be used to list all available interfaces on the system,
with no other additional information. Use of this flag is mutually
exclusive with all other flags and commands, except for -d (only list
interfaces that are down) and -u (only list interfaces that are up).
The -v flag may be used to get more verbose status for an interface.
The -C flag may be used to list all of the interface cloners available on
the system, with no additional information. Use of this flag is mutually
exclusive with all other flags and commands.
The -k flag causes keying information for the interface, if available, to
be printed. For example, the values of 802.11 WEP keys will be printed,
if accessible to the current user. This information is not printed by
default, as it may be considered sensitive.
If the network interface driver is not present in the kernel then
ifconfig will attempt to load it. The -n flag disables this behavior.
Only the super-user may modify the configuration of a network interface.
NOTES
The media selection system is relatively new and only some drivers sup-
port it (or have need for it).
EXAMPLES
Assign the IPv4 address 192.0.2.10, with a network mask of 255.255.255.0,
to the interface fxp0:
# ifconfig fxp0 inet 192.0.2.10 netmask 255.255.255.0
Add the IPv4 address 192.0.2.45, with the CIDR network prefix /28, to the
interface ed0, using add as a synonym for the canonical form of the
option alias:
# ifconfig ed0 inet 192.0.2.45/28 add
Remove the IPv4 address 192.0.2.45 from the interface ed0:
# ifconfig ed0 inet 192.0.2.45 -alias
Add the IPv6 address 2001:DB8:DBDB::123/48 to the interface em0:
# ifconfig em0 inet6 2001:db8:bdbd::123 prefixlen 48 alias
Note that lower case hexadecimal IPv6 addresses are acceptable.
Remove the IPv6 address added in the above example, using the / character
as shorthand for the network prefix, and using delete as a synonym for
the canonical form of the option -alias:
# ifconfig em0 inet6 2001:db8:bdbd::123/48 delete
Configure the interface xl0, to use 100baseTX, full duplex Ethernet media
options:
# ifconfig xl0 media 100baseTX mediaopt full-duplex
Create the software network interface gif1:
# ifconfig gif1 create
Destroy the software network interface gif1:
# ifconfig gif1 destroy
DIAGNOSTICS
Messages indicating the specified interface does not exist, the requested
address is unknown, or the user is not privileged and tried to alter an
interface's configuration.
SEE ALSO
netstat(1), carp(4), netintro(4), pfsync(4), polling(4), vlan(4), rc(8),
routed(8), sysctl(8)
HISTORY
The ifconfig utility appeared in 4.2BSD.
BUGS
Basic IPv6 node operation requires a link-local address on each interface
configured for IPv6. Normally, such an address is automatically config-
ured by the kernel on each interface added to the system; this behaviour
may be disabled by setting the sysctl MIB variable
net.inet6.ip6.auto_linklocal to 0.
If you delete such an address using ifconfig, the kernel may act very
odd. Do this at your own risk.
FreeBSD 7.2 October 19, 2008 FreeBSD 7.2
NAME - SYNOPSIS - DESCRIPTION - NOTES - EXAMPLES - DIAGNOSTICS - SEE ALSO -
HISTORY - BUGS -
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