IFCONFIG

NAME

SYNOPSIS

NOTE

DESCRIPTION

If no arguments are given, ifconfig displays the status of the currently active interfaces. If a single interface argument is given, it displays the status of the given interface only; if a single -a argument is given, it displays the status of all interfaces, even those that are down. Otherwise, it configures an interface.

Address Families

OPTIONS

interface

The name of the interface. This is usually a driver name followed by a unit number, for example eth0 for the first Ethernet interface.

up

This flag causes the interface to be activated. It is implicitly specified if an address is assigned to the interface.

down

This flag causes the driver for this interface to be shut down.

[-]arp

Enable or disable the use of the ARP protocol on this interface.

[-]promisc

Enable or disable the promiscuous mode of the interface. If selected, all packets on the network will be received by the interface.

[-]allmulti

Enable or disable all-multicast mode. If selected, all multicast packets on the network will be received by the interface.

metric N

This parameter sets the interface metric. It is not available under GNU/Linux.

mtu N

This parameter sets the Maximum Transfer Unit (MTU) of an interface.

dstaddr addr

Set the remote IP address for a point-to-point link (such as PPP). This keyword is now obsolete; use the pointopoint keyword instead.

netmask addr

Set the IP network mask for this interface. This value defaults to the usual class A, B or C network mask (as derived from the interface IP address), but it can be set to any value.

add addr/prefixlen

Add an IPv6 address to an interface.

del addr/prefixlen

Remove an IPv6 address from an interface.

tunnel ::aa.bb.cc.dd

Create a new SIT (IPv6-in-IPv4) device, tunnelling to the given destination.

irq addr

Set the interrupt line used by this device. Not all devices can dynamically change their IRQ setting.

io_addr addr

Set the start address in I/O space for this device.

mem_start addr

Set the start address for shared memory used by this device. Only a few devices need this.

media type

Set the physical port or medium type to be used by the device. Not all devices can change this setting, and those that can vary in what values they support. Typical values for type are 10base2 (thin Ethernet), 10baseT (twisted-pair 10Mbps Ethernet), AUI (external transceiver) and so on. The special medium type of auto can be used to tell the driver to auto-sense the media. Again, not all drivers can do this.

[-]broadcast [addr]

If the address argument is given, set the protocol broadcast address for this interface. Otherwise, set (or clear) the IFF_BROADCAST flag for the interface.

[-]pointopoint [addr]

This keyword enables the point-to-point mode of an interface, meaning that it is a direct link between two machines with nobody else listening on it.
If the address argument is also given, set the protocol address of the other side of the link, just like the obsolete dstaddr keyword does. Otherwise, set or clear the IFF_POINTOPOINT flag for the interface.

hw class address

Set the hardware address of this interface, if the device driver supports this operation. The keyword must be followed by the name of the hardware class and the printable ASCII equivalent of the hardware address. Hardware classes currently supported include ether (Ethernet), ax25 (AMPR AX.25), ARCnet and netrom (AMPR NET/ROM).

multicast

Set the multicast flag on the interface. This should not normally be needed as the drivers set the flag correctly themselves.

address

The IP address to be assigned to this interface.

txqueuelen length

Set the length of the transmit queue of the device. It is useful to set this to small values for slower devices with a high latency (modem links, ISDN) to prevent fast bulk transfers from disturbing interactive traffic like telnet too much.

NOTES

Interrupt problems with Ethernet device drivers fail with EAGAIN. See http://www.scyld.com/expert/irq-conflict.html for more information.

FILES

BUGS

While appletalk DDP and IPX addresses will be displayed they cannot be altered by this command.

SEE ALSO

AUTHORS