.. SPDX-License-Identifier: GPL-2.0 =========== 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.