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IFCONFIG(8) FreeBSD System Manager's Manual IFCONFIG(8)
NAME
ifconfig -- configure network interface parameters
SYNOPSIS
ifconfig [-L] [-m] interface [create] [address_family] [address
[dest_address]] [parameters]
ifconfig interface destroy
ifconfig -a [-L] [-d] [-m] [-u] [address_family]
ifconfig -l [-d] [-u] [address_family]
ifconfig [-L] [-d] [-m] [-u] [-C]
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 ``inet6'' family, it is also possible to specify the prefix
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''.
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)).
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.
eui64 (Inet6 only.) Fill interface index (lowermost 64bit of an IPv6
address) automatically.
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 10Mb/s Ethernet interface might sup-
port the use of either AUI or twisted pair connectors. Setting
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.
tunnel src_addr dest_addr
(IP tunnel devices only.) Configure the physical source and des-
tination address for IP tunnel interfaces (gif(4)). The argu-
ments src_addr and dest_addr are interpreted as the outer
source/destination for the encapsulating IPv4/IPv6 header.
deletetunnel
Unconfigure the physical source and destination address for IP
tunnel interfaces previously configured with tunnel.
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.
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.
vlan vlan_tag
If the interface is a vlan pseudo interface, set the vlan tag
value to vlan_tag. This value is a 16-bit number which is used
to create an 802.1Q vlan header for 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 pseudo device, associate physical
interface iface with it. Packets transmitted through the vlan
interface will be diverted to the specified physical interface
iface with 802.1Q vlan encapsulation. Packets with 802.1Q encap-
sulation 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 interface's
flags and the parent's ethernet address. The vlandev and 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 association to another physical interface,
the existing association must be cleared first.
Note: if the link0 flag is set on the vlan interface, the vlan
pseudo interface's behavior changes: the link0 tells the vlan
interface 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 pseudo device, disassociate the physical
interface iface from it. This breaks the link between the vlan
interface and its parent, clears its vlan tag, flags and its link
address and shuts the interface down.
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, 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.
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.
ssid ssid
For IEEE 802.11 wireless interfaces, set the desired Service Set
Identifier (aka network name). The SSID is a string up to 32
characters in length and may be specified as either a normal
string or in hexadecimal when proceeded by `0x'. Additionally,
the SSID may be cleared by setting it to `-'.
nwid ssid
Another name for the ssid parameter. Included for NetBSD compat-
ibility.
stationname name
For IEEE 802.11 wireless interfaces, set the name of this sta-
tion. It appears that the station name is not really part of the
IEEE 802.11 protocol though all interfaces seem to 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.
station name
Another name for the stationname parameter. Included for BSD/OS
compatibility.
channel number
For IEEE 802.11 wireless interfaces, set the desired channel.
Channels range from 1 to 14, but the exact selection available
depends on the region your adaptor was manufactured for. Setting
the channel to 0 will give you the default for your adaptor.
Many adaptors ignore this setting unless you are in ad-hoc mode.
authmode mode
For IEEE 802.11 wireless interfaces, set the desired authentica-
tion mode in infrastructure mode. Not all adaptors support all
modes. The set of valid modes is ``none'', ``open'', and
``shared''. Modes are case insensitive.
powersave
For IEEE 802.11 wireless interfaces, enable powersave mode.
-powersave
For IEEE 802.11 wireless interfaces, disable powersave mode.
powersavesleep sleep
For IEEE 802.11 wireless interfaces, set the desired max power-
save sleep time in milliseconds.
wepmode mode
For IEEE 802.11 wireless interfaces, set the desired WEP mode.
Not all adaptors support all modes. The set of valid modes is
``off'', ``on'', and ``mixed''. ``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 con-
nections. On other adaptors, ``on'' is generally another name
for ``mixed''. Modes are case insensitive.
weptxkey index
For IEEE 802.11 wireless interfaces, set the WEP key to be used
for transmission.
wepkey key|index:key
For IEEE 802.11 wireless interfaces, 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 net-
work and the capabilities of the adaptor. It may be specified
either as a plain string or as a string of hexadecimal digits
proceeded by `0x'. For maximum portability, hex keys are recom-
mended; the mapping of text keys to WEP encryption is usually
driver-specific. In particular, the Windows drivers do this map-
ping 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 adaptor specific keys such as perma-
nent keys stored in NVRAM.
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 compatibility.
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 compatibility.
-nwkey Another way of saying wepmode off.
Included for NetBSD compatibility.
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 driver does supports the media selection system, the supported
media list will be included in the output.
If the -m flag is passed before an interface name, ifconfig will display
all of the supported media for the specified interface. If -L flag is
supplied, address lifetime is displayed for IPv6 addresses, as time off-
set 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 -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.
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).
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.
BUGS
IPv6 link-local addresses are required for several basic communication
between IPv6 node. If they are deleted by ifconfig manually, the kernel
might show very strange behavior. So, such manual deletions are strongly
discouraged.
SEE ALSO
netstat(1), netintro(4), rc(8), routed(8)
HISTORY
The ifconfig utility appeared in 4.2BSD.
FreeBSD 4.9 July 2, 2001 FreeBSD 4.9
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