NAME
ifconfig
- configure network interface parameters
SYNOPSIS
ifconfig
interface address_family
[address [dest_address]]
[parameters]
ifconfig
[-hLmvz]
interface
[protocol_family]
ifconfig
-a
[-bdhLmsuvz]
[protocol_family]
ifconfig
-l
[-bdsu]
ifconfig
-s
interface
ifconfig
-C
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
:
- 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
:
- 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.
- 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.
- -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 don't 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.
- ssid id
-
(IEEE 802.11 devices only)
Configure the Service Set Identifier (a.k.a. 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 forwared 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 doesn't affect the channel to be created for IBSS or hostap mode.
- Bk -words
-
- 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 symbolicaly.
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.
- 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.
- tentative
-
(inet6 only)
Set the IPv6 tentative address bit.
- -tentative
-
(inet6 only)
Clear the IPv6 tentative 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.
- 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.
- 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.
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.
-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.
Only the super-user may modify the configuration of a network interface.
EXAMPLES
Add a link-layer address to an Ethernet:
ifconfig sip0 link 00:11:22:33:44:55
Add and activate a link-layer 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),
vlan(4),
ifconfig.if(5),
rc(8),
routed(8)
HISTORY
The
ifconfig
command appeared in
4.2BSD.