ifconfig linux command

ifconfig

ifconfig [interface]

ifconfig [interface address_family parameters addresses]

TCP/IP command. Assign an address to a network interface and/or configure network interface parameters. ifconfig is typically used at boot time to define the network address of each interface on a machine. It may be used at a later time to redefine an interface's address or other parameters. Without arguments, ifconfig displays the current configuration for a network interface. Used with a single interface argument, ifconfig displays that particular interface's current configuration.

Arguments

interface

String of the form name unit, for example, en0.

address_family

Since an interface may receive transmissions in differing protocols, each of which may require separate naming schemes, you can specify the address_family to change the interpretation of the remaining parameters. You may specify inet (the default; for TCP/IP), ax25 (AX.25 Packet Radio), ddp (Appletalk Phase 2), or ipx (Novell).

Parameters

The following parameters may be set with ifconfig:

allmulti/-allmulti

Enable/disable sending of incoming frames to the kernel's network layer.

arp/-arp

Enable/disable use of the Address Resolution Protocol in mapping between network-level addresses and link-level addresses.

broadcast

(inet only.) Specify address to use to represent broadcasts to the network. Default is the address with a host part of all 1s (i.e., x.y.z.255 for a class C network).

debug/-debug

Enable/disable driver-dependent debugging code.

dest_address

Specify the address of the correspondent on the other end of a point-to-point link.

down

Mark an interface 'down' (unresponsive).

hw class address

Set the interface's hardware class and address. class may be ether (Ethernet), ax25 (AX.25 Packet Radio), or ARCnet.

irq addr

Set the device's interrupt line.

metric n

Set routing metric of the interface to n. Default is 0.

mtu num

Set the interface's Maximum Transfer Unit (MTU).

multicast

Set the multicast flag.

netmask mask

(inet only.) Specify how much of the address to reserve for subdividing networks into subnetworks. mask can be specified as a single hexadecimal number with a leading 0x, with a dot notation Internet address, or with a pseudonetwork name listed in the network table /etc/networks.

pointopoint/-pointopoint [address]

Enable/disable point-to-point interfacing, so that the connection between the two machines is dedicated.

up

Mark an interface 'up' (ready to send and receive).

trailers/-trailers

Request/disable use of a 'trailer' link-level encapsulation when sending.

address

Either a hostname present in the hostname database (/etc/hosts), or an Internet address expressed in the Internet standard dot notation.