ifconfig - configure network interface parameters
ifconfig interface [address_family] [address [dest_address]]
ifconfig -A | -Am | -a | -am [address_family]
ifconfig -m interface [address_family]
ifconfig interface create
ifconfig interface destroy
ifconfig carp-interface vhid host-id
ifconfig pfsync-interface syncpeer peer_address syncif iface
ifconfig tunnel-interface tunnel src_address dest_address
ifconfig tunnel-interface deletetunnel
ifconfig vlan-interface vlan vlan-tag vlandev
ifconfig interface group group-name
The ifconfig utility 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
address or other operating parameters. To configure a
use the brconfig(8) program instead.
ifconfig displays the current configuration for a network
no optional parameters are supplied. If a protocol family
ifconfig will report only the details specific to that protocol family.
Only the superuser may modify the configuration of a network
The options are as follows:
-A Causes full interface alias information for each interface to be
-Am The same as the -A option, but additionally prints
information for all interfaces.
-a Causes ifconfig to print information on all interfaces. The protocol
family may be specified as well.
-am The same as the -a option, but additionally prints
information for all interfaces.
-C Print the names of all network pseudo-devices that
can be created
dynamically at runtime using ifconfig create.
Print media information for a given interface.
For the DARPA Internet family, the address is either
a host name
present in the host name database, hosts(5), or a
address expressed in the Internet standard ``dot notation''.
Internet version 6 addresses are either a host name
the host name database, hosts(5), or an Internet
version 6 address
in standard colon separated form, as described
inet(3) manual page.
For the Xerox Network Systems(tm) and Internetwork
families, addresses are of the form
where ``net'' is the assigned network number (in
each of the six bytes of the host number, ``a''
are specified in hexadecimal. The host number may
be omitted on
Ethernet interfaces, which use the hardware physical
on interfaces other than the first.
AppleTalk (LLAP) addresses are specified as
Number.Node Address''). Node addresses are divided
classes: User Node IDs and Server Node IDs.
for User Node IDs while 128-254($80-$FE) are used
for Server Node
IDs. Node 0($00) is not allowed (unknown) while
Node 255($FF) is
reserved for the AppleTalk broadcast hardware address (broadcast
IPX addresses are specified as listed in the ipx(3)
Specifies the address family which affects interpretation of the
remaining parameters. Since an interface can receive transmissions
in differing protocols with different naming
the address family is recommended. The address or protocol
families currently supported are ``inet'', ``inet6'',
``atalk'', ``ipx'', and ``ns''.
The interface parameter is a string of the form
for example, ``en0''. If no optional parameters are
this string can instead be just ``name''. In this
case, all interfaces
of that type will be displayed. For example, ``carp''
will display the current configuration of all
The following parameters may be set with ifconfig:
802.2 802.2tr 802.3 snap EtherII
Set the ipx(3) frame type to be either
802.3, snap, or Ethernet II.
advbase n If the driver is a carp(4) pseudo-device,
set the base
advertisement interval to n seconds. This
is 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 and advskew indicate how frequently,
in seconds, the host will advertise
that it considers itself master of the virtual host. The
formula is advbase + (advskew / 255 ). If
does not advertise within three times this
host will begin advertising as master.
alias Establish an additional network address for
This is sometimes useful when changing network
numbers, and one wishes to accept packets
the old interface.
-alias Remove the specified network address alias.
anycast (inet6 only) Set the IPv6 anycast address
-anycast (inet6 only) Clear the IPv6 anycast address
arp Enable the use of the Address Resolution
(``ARP''; see arp(4)) in mapping between
addresses and link level addresses (default). This is
currently implemented for mapping between
addresses and Ethernet addresses.
-arp Disable the use of ARP.
broadcast addr (inet only) Specify the address to use to
broadcasts to the network. The default
is the address with a host part of all 1's.
create Create the specified network pseudo-device.
At least the
following devices can be created on demand:
bridge(4), carp(4), gif(4), gre(4), lo(4),
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
longer needed. If you have incorrectly set
an NS address
having the side effect of specifying the
removing all NS addresses will allow you to
deletetunnel Removes the source and destination tunnel
onto a tunnel interface.
Specify a description of the interface.
This can be used
to label interfaces in situations where they
be difficult to distinguish.
dest_address Specify the address of the correspondent on
the other end
of a point-to-point link.
destroy Destroy the specified network pseudo-device.
down Mark an interface ``down''. When an interface is marked
``down'', the system will not attempt to
through that interface. If possible,
will be reset to disable reception as well.
automatically disables routes using the interface.
Assign the interface to a ``group''. Any
be in multiple groups. Interface groups are
Remove the interface from the given
eui64 (inet6 only) Fill the interface index (the
bit of an IPv6 address) automatically.
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.
ipdst addr This is used to specify an Internet host
which is willing
to receive IP packets encapsulating NS packets bound for
a remote network. An apparent point-topoint link is
constructed, and the address specified will
be taken as
the NS address and network of the destination. IP encapsulation
of Connectionless Network Protocol
packets is done differently.
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
maxupd n If the driver is a pfsync(4) pseudo-device,
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.
media type Set the media type of the interface to type.
support the mutually exclusive use of
one of several
different physical media connectors. For
10Mb/s Ethernet interface might support the
use of either
AUI or twisted pair connectors. Setting the
to ``10base5'' or ``AUI'' would change the
connector to the AUI port. Setting it
``10baseT'' or ``UTP'' would activate twisted pair. Refer
to the interface's driver-specific man
page for a
complete list of the available types, or use
$ ifconfig -m interface
for a listing of choices.
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 interface's driverspecific man
page for a complete list of available options, or use
$ ifconfig -m interface
for a listing of choices.
-mediaopt opts Disable the specified media options on the
metric nhops Set the routing metric of the interface to
0. The routing metric is used by the routing protocol
(see routed(8)). Higher metrics have the
effect of making
a route less favorable; metrics are
counted as addition
hops to the destination network or
mtu value Set the MTU for this device to the given
routes will inherit this value as a default.
netmask mask (inet and inet6) Specify how much of the address to reserve
for subdividing networks into subnetworks. The
mask includes the network part of the local
the subnet part, which is taken from the
host field of
the address. The mask can be specified as a
number with a leading 0x, with a
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
network portion, and the subnet field should
with the network portion.
nwid id (IEEE 802.11 devices only) Configure network
ID 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 hexadecimal digits up to 64 digits. The empty
string allows the interface to connect to
nwkey key (IEEE 802.11 devices only) Enable WEP encryption for IEEE
802.11-based wireless network interfaces using the specified
key. The key can either be a string, a
hexadecimal digits (preceded by `0x'), or a
set of keys
of the form ``n:k1,k2,k3,k4'' where `n'
of the keys will be used for transmitted
packets, and the
four keys, ``k1'' through ``k4'', are configured as WEP
keys. If a set of keys is specified, a comma (`,') within
the key must be escaped with a backslash.
if multiple keys are used, their order must
be the same
within the network. For IEEE 802.11 wireless networks,
the length of each key is restricted to 40
bits, i.e. a
5-character string or 10 hexadecimal digits.
Gold and newer Prism cards will also accept a
104-bit (13-character) key.
-nwkey (IEEE 802.11 devices only) Disable WEP encryption for
IEEE 802.11-based wireless network interfaces.
nwkey persist (IEEE 802.11 devices only) Enable WEP encryption for IEEE
802.11-based wireless network interfaces
with the persistent
key stored in the network card.
(IEEE 802.11 devices only) Write key to the
memory of the network card, and enable WEP
IEEE 802.11-based wireless network interfaces using that
If the driver is a carp(4) pseudo-device,
set the authentication
key to passphrase. There is no
phase n The argument n specifies the version (phase)
of the AppleTalk
network attached to the interface.
Values of 1
or 2 are permitted.
pltime n (inet6 only) Set preferred lifetime for the
powersave (IEEE 802.11 devices only) Enable 802.11
-powersave (IEEE 802.11 devices only) Disable 802.11
(IEEE 802.11 devices only) Set the receiver
(in milliseconds) for 802.11 power saving mode.
prefixlen n (inet and inet6 only) Effect is similar to
you can specify prefix length by digits.
range netrange Under AppleTalk, set the interface to respond to a
netrange of the form ``startnet-endnet''.
this scheme instead of netmasks though
it internally as a set of netmasks.
state state Explicitly force the carp(4) pseudo-device
to enter this
state. Valid states are init, backup, and
If the driver is a pfsync(4) pseudo-device,
make the pfsync
link point-to-point rather than using
broadcast the state synchronisation messages. The
peer_address is the IP address of the other
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,
packets using multicast.
syncif iface If the driver is a pfsync(4) pseudo-device,
use the specified
interface to send and receive pfsync
-syncif If the driver is a pfsync(4) pseudo-device,
pfsync state synchronisation messages over
tentative (inet6 only) Set the IPv6 tentative address
-tentative (inet6 only) Clear the IPv6 tentative address bit.
Set the timeslot range map, which is used to
which channels an interface device uses.
tunnel src_address dest_address
Set the source and destination tunnel addresses on a tunnel
interface, including gif(4). Packets
routed to this
interface will be encapsulated in IPv4 or
on the source and destination address families. Both addresses
must be of the same family.
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
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
vlan vlan_tag If the interface is a vlan(4) pseudo-interface, set the
vlan tag value to vlan_tag. This value is a
which is used to create an 802.1Q vlan
packets sent from the vlan interface. Note
that vlan and
vlandev must both be set at the same time.
vlandev iface If the interface is a vlan(4) pseudo-device,
physical interface iface with it. Packets
through the vlan interface will be diverted
to the specified
physical interface iface with 802.1Q
Packets with 802.1Q encapsulation received by the
parent interface with the correct vlan tag
will be diverted
to the associated vlan pseudo-interface. The vlan
interface is assigned a copy of the parent
flags and the parent's Ethernet address.
vlan must both be set at the same time. If
the vlan interface
already has a physical interface associated with
it, this command will fail. To change the
another physical interface, the existing association must
be cleared first.
Note: if the link0 flag is set on the vlan
vlan pseudo-interface's behavior changes;
link0 tells the
vlan interface that the parent interface
and extraction of vlan tags on its own
firmware) and that it should pass packets to
and from the
-vlandev If the driver is a vlan(4) pseudo-device,
the physical interface from it. This breaks
the link between
the vlan interface and its parent,
clears its vlan
tag, flags, and link address, and shuts the
vltime n (inet6 only) Set valid lifetime for the address.
Assign the inet(3) address of 192.168.1.10 with a network
255.255.255.0 to interface fxp0:
# ifconfig fxp0 inet 192.168.1.10 netmask
Assign the ipx(3) address of 12625920 specified in decimal
# ifconfig fxp0 ipx 12625920
Assign the AppleTalk network 39108 and server node 128 with
range of 39107-39109 to interface fxp0 on a phase 2 AppleTalk network:
# ifconfig fxp0 atalk 39108.128 range 39107-39109
Configure the xl0 interface to use 10baseT:
# ifconfig xl0 media 10baseT
Configure the xl0 interface to use 100baseTX, full duplex:
# ifconfig xl0 media 100baseTX mediaopt full-duplex
Label the em0 interface as an uplink:
# ifconfig em0 description "Uplink to Gigabit Switch
Configure the vlan0 interface for IP address 192.168.254.1,
vlan tag 4,
and vlan parent device fxp0:
# ifconfig vlan0 192.168.254.1 vlan 4 vlandev fxp0
Configure the carp0 interface for IP address 192.168.10.1,
# ifconfig carp0 vhid 1 192.168.10.1
Create the gif1 network interface:
# ifconfig gif1 create
Destroy the gif1 network interface:
# ifconfig gif1 destroy
Messages indicating the specified interface does not exist,
address is unknown, or the user is not privileged and tried
to alter an
netstat(1), inet(3), ipx(3), arp(4), bridge(4), carp(4),
ifmedia(4), inet(4), lo(4), netintro(4), pfsync(4), ppp(4),
tun(4), vlan(4), hostname.if(5), hosts(5), networks(5), brconfig(8),
The ifconfig command appeared in 4.2BSD.
OpenBSD 3.6 September 3, 1998
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