IFCONFIG
Section: Maintenance Commands (8)
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BSD mandoc
BSD 4.2
NAME
ifconfig
- configure network interface parameters
SYNOPSIS
ifconfig
interface address_family
[address
[dest_address
]
]
[parameters
]
ifconfig
[-m
]
interface
[protocol_family
]
ifconfig
-a
[-m
]
[-d
]
[-u
]
[protocol_family
]
ifconfig
-l
[-d
]
[-u
]
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''
- 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''
``atalk''
and
``ipx''
- Interface
-
The
interface
parameter is a string of the form
``name unit''
for example,
``en0 ''
The following parameters may be set with
ifconfig
- 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.
- 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 10Mb/s Ethernet addresses.
- -arp
-
Disable the use of the Address Resolution Protocol.
- 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.
- 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.
- 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.
- 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/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 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.
- 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 restrictions.
- netmask mask
-
(Inet only)
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.
- range
-
Under appletalk, set the interface to respond to a
netrange.
of the form startnet-endnet. Appletalk uses this scheme instead of
netmasks though FreeBSD impliments it internally as a set of netmasks.
- 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, 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.
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
-m
flag is passed before an interface name,
ifconfig
will display all of the supported media for the specified interface.
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, and
-u
limits this to interfaces that are up.
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).
Only the super-user may modify the configuration of a network interface.
DIAGNOSTICS
Messages indicating the specified interface does not exit, the
requested address is unknown, or the user is not privileged and
tried to alter an interface's configuration.
SEE ALSO
netstat(1),
netintro(4),
rc(8),
routed(8)
HISTORY
The
ifconfig
command appeared in
BSD 4.2
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- DIAGNOSTICS
-
- SEE ALSO
-
- HISTORY
-
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Time: 03:08:41 GMT, January 13, 2023