NAME
ifconfig —
configure network interface
parameters
SYNOPSIS
ifconfig |
[-N] interface
address_family [address
[dest_address]]
[parameters] |
ifconfig |
[-hLmNvz]
interface
[protocol_family] |
ifconfig |
-a
[-bdhLNmsuvz]
[protocol_family] |
ifconfig |
-w secs
[-W
secs] |
DESCRIPTION
ifconfig is used to assign an address to a network interface
and/or configure network interface parameters.
ifconfig 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.
Available operands for
ifconfig:
-
-
- 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”. For
the Xerox Network Systems(tm) family, addresses are
net:a.b.c.d.e.f, where net is
the assigned network number (in decimal), and each of the six bytes of the
host number, a through f, are
specified in hexadecimal. The host number may be omitted on Ethernet
interfaces, which use the hardware physical address, and on interfaces
other than the first. For the ISO family, addresses are specified as a
long hexadecimal string, as in the Xerox family. However, two consecutive
dots imply a zero byte, and the dots are optional, if the user wishes to
(carefully) count out long strings of digits in network byte order.
-
-
- address_family
- Specifies the address_family which
affects interpretation of the remaining parameters. Since an interface can
receive transmissions in differing protocols with different naming
schemes, specifying the address family is recommended. The address or
protocol families currently supported are “inet”,
“inet6”, “atalk”, “iso”, and
“link”.
-
-
- interface
- The interface parameter is a string
of the form “name unit”, for example, “en0”
The following parameters may be set with
ifconfig:
-
-
- active
- This keyword applies when ifconfig adds
or modifies any link-layer address. It indicates that
ifconfig should “activate” the address.
Activation makes an address the default source for transmissions on the
interface. You may not delete the active address from an interface. You
must activate some other address, first.
-
-
- advbase
n
- If the driver is a
carp(4) pseudo-device, set the
base advertisement interval to n seconds. This ia an
8-bit number; the default value is 1 second.
-
-
- advskew
n
- If the driver is a
carp(4) pseudo-device, skew
the advertisement interval by n. This is an 8-bit
number; the default value is 0.
Taken together the advbase indicate how frequently, in
seconds, the host will advertise the fact that it considers itself the
master of the virtual host. The formula is advbase +
(advskew / 256). If the master does not advertise within
three times this interval, this host will begin advertising as
master.
-
-
- 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.
-
-
- -alias
- Remove the specified network address alias.
-
-
- arp
- Enable the use of the Address Resolution Protocol in
mapping between network level addresses and link level addresses
(default). This is currently implemented for mapping between DARPA
Internet addresses and Ethernet addresses.
-
-
- -arp
- Disable the use of the Address Resolution Protocol.
-
-
- anycast
- (inet6 only) Set the IPv6 anycast address bit.
-
-
- -anycast
- (inet6 only) Clear the IPv6 anycast address bit.
-
-
- broadcast
mask
- (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.
-
-
- carpdev
iface
- If the driver is a
carp(4) pseudo-device, attach
it to iface. If not specified, the kernel will
attempt to select an interface with a subnet matching that of the carp
interface.
-
-
- debug
- Enable driver dependent debugging code; usually, this turns
on extra console error logging.
-
-
- -debug
- Disable driver dependent debugging code.
-
-
- delete
- 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. delete does not work for IPv6
addresses. Use -alias with explicit IPv6 address
instead.
-
-
- dest_address
- Specify the address of the correspondent on the other end
of a point to point link.
-
-
- 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.
-
-
- ipdst
- This is used to specify an Internet host who is willing to
receive ip packets encapsulating NS packets bound for a remote network. An
apparent point to point link is constructed, and the address specified
will be taken as the NS address and network of the destination. IP
encapsulation of CLNP packets is done differently.
-
-
- media
type
- Set the media type of the interface to
type. Some interfaces support the mutually exclusive
use of one of several different physical media connectors. For example, a
10Mb/s Ethernet interface might support the use of either AUI or twisted
pair connectors. Setting the media type to “10base5” or
“AUI” would change the currently active connector to the AUI
port. Setting it to “10baseT” or “UTP” would
activate twisted pair. Refer to the interfaces' driver specific man page
for a complete list of the available types and the
ifmedia(4) manual page for
a list of media types. See the -m flag below.
-
-
- mediaopt
opts
- Set the specified media options on the interface.
opts 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. Also see the
ifmedia(4) manual page for
a list of media options.
-
-
- -mediaopt
opts
- Disable the specified media options on the interface.
-
-
- mode
mode
- If the driver supports the media selection system, set the
specified 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.
-
-
- instance
minst
- Set the media instance to minst. This
is useful for devices which have multiple physical layer interfaces
(PHYs). Setting the instance on such devices may not be strictly required
by the network interface driver as the driver may take care of this
automatically; see the driver's manual page for more information.
-
-
- 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
addition hops to the destination network or host.
-
-
- mtu
n
- Set the maximum transmission unit of the interface to
n. Most interfaces do not support this option.
-
-
- netmask
mask
- (inet, inet6, and ISO) Specify how much of the address to
reserve for subdividing networks into sub-networks. The mask includes the
network part of the local address and the subnet part, which is taken from
the host field of the address. The mask can be specified 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.
For INET and INET6 addresses, the netmask can also be given with
slash-notation after the address (e.g 192.168.17.3/24).
-
-
- nsellength
n
- (ISO only) This specifies a trailing number of bytes for a
received NSAP used for local identification, the remaining leading part of
which is taken to be the NET (Network Entity Title). The default value is
1, which is conformant to US GOSIP. When an ISO address is set in an
ifconfig command, it is really the NSAP which is being specified. For
example, in US GOSIP, 20 hex digits should be specified in the ISO NSAP to
be assigned to the interface. There is some evidence that a number
different from 1 may be useful for AFI 37 type addresses.
-
-
- state
state
- Explicitly force the
carp(4) pseudo-device to enter
this state. Valid states are init,
backup, and master.
-
-
- frag
threshold
- (IEEE 802.11 devices only) Configure the fragmentation
threshold for IEEE 802.11-based wireless network interfaces.
-
-
- rts
threshold
- (IEEE 802.11 devices only) Configure the RTS/CTS threshold
for IEEE 802.11-based wireless network interfaces. This controls the
number of bytes used for the RTS/CTS handshake boundary. The
threshold can be any value between 0 and 2347. The
default is 2347, which indicates the RTS/CTS mechanism should not be
used.
-
-
- ssid
id
- (IEEE 802.11 devices only) Configure the Service Set
Identifier (aka the network name) for IEEE 802.11-based wireless network
interfaces. The id can either be any text string up
to 32 characters in length, or a series of up to 64 hexadecimal digits
preceded by “0x”. Setting id to the
empty string allows the interface to connect to any available access
point.
-
-
- nwid
id
- Synonym for “ssid”.
-
-
- hidessid
- (IEEE 802.11 devices only) 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.
-
-
- -hidessid
- (IEEE 802.11 devices only) When operating as an access
point, broadcast the SSID in beacon frames and answer and respond to
undirected probe request frames (default).
-
-
- nwkey
key
- (IEEE 802.11 devices only) Enable WEP encryption for IEEE
802.11-based wireless network interfaces with the
key. The key can either be a
string, a series of hexadecimal digits preceded by “0x”, or a
set of keys in the form n:k1,k2,k3,k4, where
n specifies which of keys will be used for all
transmitted packets, and four keys, k1 through
k4, are configured as WEP keys. Note that the order
must be match within same network if multiple keys are used. For IEEE
802.11 wireless network, the length of each key is restricted to 40 bits,
i.e., 5-character string or 10 hexadecimal digits, while the WaveLAN/IEEE
Gold cards accept the 104 bits (13 characters) key.
-
-
- nwkey
persist
- (IEEE 802.11 devices only) Enable WEP encryption for IEEE
802.11-based wireless network interfaces with the persistent key written
in the network card.
-
-
- nwkey
persist:key
- (IEEE 802.11 devices only) Write the
key to the persistent memory of the network card,
and enable WEP encryption for IEEE 802.11-based wireless network
interfaces with the key.
-
-
- -nwkey
- (IEEE 802.11 devices only) Disable WEP encryption for IEEE
802.11-based wireless network interfaces.
-
-
- apbridge
- (IEEE 802.11 devices only) When operating as an access
point, pass packets between wireless clients directly (default).
-
-
- -apbridge
- (IEEE 802.11 devices only) When operating as an access
point, pass packets through the system so that they can be forwarded using
some other mechanism. Disabling the internal bridging is useful when
traffic is to be processed with packet filtering.
-
-
- pass
passphrase
- If the driver is a
carp(4) pseudo-device, set the
authentication key to passphrase. There is no
passphrase by default
-
-
- powersave
- (IEEE 802.11 devices only) Enable 802.11 power saving
mode.
-
-
- -powersave
- (IEEE 802.11 devices only) Disable 802.11 power saving
mode.
-
-
- powersavesleep
duration
- (IEEE 802.11 devices only) Set the receiver sleep duration
in milliseconds for 802.11 power saving mode.
-
-
- bssid
bssid
- (IEEE 802.11 devices only) Set the desired BSSID for IEEE
802.11-based wireless network interfaces.
-
-
- -bssid
- (IEEE 802.11 devices only) Unset the desired BSSID for IEEE
802.11-based wireless network interfaces. The interface will automatically
select a BSSID in this mode, which is the default.
-
-
- chan
chan
- (IEEE 802.11 devices only) Select the channel (radio
frequency) to be used for IEEE 802.11-based wireless network
interfaces.
-
-
- -chan
- (IEEE 802.11 devices only) Unset the desired channel to be
used for IEEE 802.11-based wireless network interfaces. It does not affect
the channel to be created for IBSS or hostap mode.
-
-
- list
scan
- (IEEE 802.11 devices only) 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 symbolically. The interface
must be up before any scanning operation. Only the super-user can use this
command.
-
-
- tunnel
src_addr[,src_port]
dest_addr[,dest_port]
- (IP tunnel devices only) Configure the physical source and
destination address for IP tunnel interfaces, including
gif(4). The arguments
src_addr and dest_addr are
interpreted as the outer source/destination for the encapsulating
IPv4/IPv6 header.
On a gre(4) interface in UDP
mode, the arguments src_port and
dest_port are interpreted as the outer
source/destination port for the encapsulating UDP header.
-
-
- deletetunnel
- Unconfigure the physical source and destination address for
IP tunnel interfaces previously configured with
tunnel.
-
-
- session
local_session
remote_session
- (L2TPv3 devices only) Configure local session id and remote
session id for L2TPv3 interface. The length of session id is 4 bytes.
-
-
- deletesession
- Unconfigure the local session id and remote session id for
L2TPv3 interface previously configured with
session.
-
-
- cookie
local_cookie_length local_cookie
remote_cookie_length
remote_cookie
- (L2TPv3 devices only) Configure local cookie and remote
cookie for L2TPv3 interface. The cookie length must be 4 or 8 bytes.
Generally, cookies are managed by daemon. So, this command would be used
for test or debug only.
-
-
- deletecookie
- Unconfigure the local cookie and remote cookie for L2TPv3
interface previously configured with cookie.
-
-
- create
- Create the specified network pseudo-device.
-
-
- destroy
- Destroy the specified network pseudo-device.
-
-
- pltime
n
- (inet6 only) Set preferred lifetime for the address.
-
-
- prefixlen
n
- (inet and inet6 only) Effect is similar to
netmask. but you can specify by prefix length by
digits.
-
-
- deprecated
- (inet6 only) Set the IPv6 deprecated address bit.
-
-
- -deprecated
- (inet6 only) Clear the IPv6 deprecated address bit.
-
-
- eui64
- (inet6 only) Fill interface index (lowermost 64bit of an
IPv6 address) automatically.
-
-
- link[0-2]
- Enable special processing of the link level of the
interface. These three options are interface specific in actual effect,
however, they are in general used to select special modes of operation. 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.
-
-
- linkstr
- Set a link-level string parameter for the interface. This
functionality varies from interface to interface. Refer to the man page
for the specific driver for more information.
-
-
- -linkstr
- Remove an interface link-level string parameter.
-
-
- up
- Mark an interface ``up''. This may be used to enable an
interface 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-initialized.
-
-
- vhid
n
- If the driver is a
carp(4) pseudo-device, set the
virtual host ID to n. Acceptable values are 1 to
255.
-
-
- vlan
vid
- If the interface is a
vlan(4) pseudo-interface, set
the VLAN identifier to vid. These are the first 12
bits (0-4095) from a 16-bit integer used to create an 802.1Q VLAN header
for packets sent from the
vlan(4) interface. Note that
vlan and vlanif must be set at the
same time.
-
-
- vlanif
iface
- If the interface is a
vlan(4) pseudo-interface,
associate the physical interface iface with it.
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 physical interface with the correct VLAN tag will be diverted to
the associated vlan(4)
pseudo-interface. The VLAN interface is assigned a copy of the physical
interface's flags and Ethernet address. 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 that vlanif and
vlan must be set at the same time.
-
-
- -vlanif
iface
- Dissociate iface from the
vlan(4) interface.
-
-
- agrport
iface
- Add iface to the
agr(4) interface.
-
-
- -agrport
iface
- Remove iface from the
agr(4) interface.
-
-
- vltime
n
- (inet6 only) Set valid lifetime for the address.
-
-
- ip4csum
- Shorthand of “ip4csum-tx ip4csum-rx”
-
-
- -ip4csum
- Shorthand of “-ip4csum-tx -ip4csum-rx”
-
-
- tcp4csum
- Shorthand of “tcp4csum-tx tcp4csum-rx”
-
-
- -tcp4csum
- Shorthand of “-tcp4csum-tx -tcp4csum-rx”
-
-
- udp4csum
- Shorthand of “udp4csum-tx udp4csum-rx”
-
-
- -udp4csum
- Shorthand of “-udp4csum-tx -udp4csum-rx”
-
-
- tcp6csum
- Shorthand of “tcp6csum-tx tcp6csum-rx”
-
-
- -tcp6csum
- Shorthand of “-tcp6csum-tx -tcp6csum-rx”
-
-
- udp6csum
- Shorthand of “udp6csum-tx udp6csum-rx”
-
-
- -udp6csum
- Shorthand of “-udp6csum-tx -udp6csum-rx”
-
-
- ip4csum-tx
- Enable hardware-assisted IPv4 header checksums for the
out-bound direction.
-
-
- -ip4csum-tx
- Disable hardware-assisted IPv4 header checksums for the
out-bound direction.
-
-
- ip4csum-rx
- Enable hardware-assisted IPv4 header checksums for the
in-bound direction.
-
-
- -ip4csum-rx
- Disable hardware-assisted IPv4 header checksums for the
in-bound direction.
-
-
- tcp4csum-tx
- Enable hardware-assisted TCP/IPv4 checksums for the
out-bound direction.
-
-
- -tcp4csum-tx
- Disable hardware-assisted TCP/IPv4 checksums for the
out-bound direction.
-
-
- tcp4csum-rx
- Enable hardware-assisted TCP/IPv4 checksums for the
in-bound direction.
-
-
- -tcp4csum-rx
- Disable hardware-assisted TCP/IPv4 checksums for the
in-bound direction.
-
-
- udp4csum-tx
- Enable hardware-assisted UDP/IPv4 checksums for the
out-bound direction.
-
-
- -udp4csum-tx
- Disable hardware-assisted UDP/IPv4 checksums for the
out-bound direction.
-
-
- udp4csum-rx
- Enable hardware-assisted UDP/IPv4 checksums for the
in-bound direction.
-
-
- -udp4csum-rx
- Disable hardware-assisted UDP/IPv4 checksums for the
in-bound direction.
-
-
- tcp6csum-tx
- Enable hardware-assisted TCP/IPv6 checksums for the
out-bound direction.
-
-
- -tcp6csum-tx
- Disable hardware-assisted TCP/IPv6 checksums for the
out-bound direction.
-
-
- tcp6csum-rx
- Enable hardware-assisted TCP/IPv6 checksums for the
in-bound direction.
-
-
- -tcp6csum-rx
- Disable hardware-assisted TCP/IPv6 checksums for the
in-bound direction.
-
-
- udp6csum-tx
- Enable hardware-assisted UDP/IPv6 checksums for the
out-bound direction.
-
-
- -udp6csum-tx
- Disable hardware-assisted UDP/IPv6 checksums for the
out-bound direction.
-
-
- udp6csum-rx
- Enable hardware-assisted UDP/IPv6 checksums for the
in-bound direction.
-
-
- -udp6csum-rx
- Disable hardware-assisted UDP/IPv6 checksums for the
in-bound direction.
-
-
- tso4
- Enable hardware-assisted TCP/IPv4 segmentation on
interfaces that support it.
-
-
- -tso4
- Disable hardware-assisted TCP/IPv4 segmentation on
interfaces that support it.
-
-
- tso6
- Enable hardware-assisted TCP/IPv6 segmentation on
interfaces that support it.
-
-
- -tso6
- Disable hardware-assisted TCP/IPv6 segmentation on
interfaces that support it.
-
-
- maxupd
n
- If the driver is a
pfsync(4) pseudo-device,
indicate 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.
-
-
- syncdev
iface
- If the driver is a
pfsync(4) pseudo-device, use
the specified interface to send and receive pfsync state synchronisation
messages.
-
-
- -syncdev
- If the driver is a
pfsync(4) pseudo-device,
stop sending pfsync state synchronisation messages over the network.
-
-
- syncpeer
peer_address
- If the driver is a
pfsync(4) pseudo-device,
make the pfsync link point-to-point rather than using multicast to
broadcast the state synchronisation messages. The peer_address is the IP
address of the other host taking part in the pfsync cluster. With this
option, pfsync(4) traffic
can be protected using
ipsec(4).
-
-
- -syncpeer
- If the driver is a
pfsync(4) pseudo-device,
broadcast the packets using multicast.
ifconfig 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 protocol family.
If the
-s flag is passed before an interface name,
ifconfig will attempt to query the interface for its media
status. If the interface supports reporting media status, and it reports that
it does not appear to be connected to a network,
ifconfig
will exit with status of 1 (false); otherwise, it will exit with a zero (true)
exit status. Not all interface drivers support media status reporting.
If the
-m flag is passed before an interface name,
ifconfig will display all of the supported media for the
specified interface. If the
-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. This is also the default behaviour when no
arguments are given to
ifconfig on the command line. When
-a is used, the output can be modified by adding more flags:
-d limits this to interfaces that are down,
-u limits this to interfaces that are up,
-b limits this to broadcast interfaces, and
-s omits interfaces which appear not to be connected to a
network.
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),
-u (only list
interfaces that are up),
-s (only list interfaces that may
be connected),
-b (only list broadcast interfaces).
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
-v flag prints statistics on packets sent and received on
the given interface. If
-h is used in conjunction with
-v, the byte statistics will be printed in
"human-readable" format. The
-z flag is identical
to the
-v flag except that it zeros the interface input and
output statistics after printing them.
The
-w flag may be used to wait
seconds
seconds for the
tentative flag to be removed from all
addresses. 0 seconds means to wait indefinitely until all addresses no longer
have the
tentative flag. The optional
-W
flag may be used to wait
seconds seconds during the
above time for the detached flag to be removed from all addresses whose
interface is marked ``up'' as well. The detached flag is set when the
interface does not have a carrier.
The
-N flag is just the opposite of the
-n
flag in
netstat(1) or in
route(8): it tells
ifconfig to try to resolve numbers to hostnames or to
service names. The default
ifconfig behavior is to print
numbers instead of names.
Only the super-user may modify the configuration of a network interface.
EXAMPLES
Add a link-layer (MAC) address to an Ethernet:
ifconfig sip0 link 00:11:22:33:44:55
Add and activate a link-layer (MAC) address:
ifconfig sip0 link 00:11:22:33:44:55 active
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),
agr(4),
carp(4),
ifmedia(4),
netintro(4),
pfsync(4),
vlan(4),
ifconfig.if(5),
rc(8),
routed(8)
HISTORY
The
ifconfig command appeared in
4.2BSD.