# IP-Aliasing¶

IP-aliases are an obsolete way to manage multiple IP-addresses/masks per interface. Newer tools such as iproute2 support multiple address/prefixes per interface, but aliases are still supported for backwards compatibility.

An alias is formed by adding a colon and a string when running ifconfig. This string is usually numeric, but this is not a must.

## Alias creation¶

Alias creation is done by 'magic' interface naming: eg. to create a 200.1.1.1 alias for eth0 ...

# ifconfig eth0:0 200.1.1.1  etc,etc....
~~ -> request alias #0 creation (if not yet exists) for eth0


The corresponding route is also set up by this command. Please note: The route always points to the base interface.

## Alias deletion¶

The alias is removed by shutting the alias down:

# ifconfig eth0:0 down
~~~~~~~~~~ -> will delete alias


## Alias (re-)configuring¶

Aliases are not real devices, but programs should be able to configure and refer to them as usual (ifconfig, route, etc).

## Relationship with main device¶

If the base device is shut down the added aliases will be deleted too.