1.. SPDX-License-Identifier: GPL-2.0 2 3=========== 4IP-Aliasing 5=========== 6 7IP-aliases are an obsolete way to manage multiple IP-addresses/masks 8per interface. Newer tools such as iproute2 support multiple 9address/prefixes per interface, but aliases are still supported 10for backwards compatibility. 11 12An alias is formed by adding a colon and a string when running ifconfig. 13This string is usually numeric, but this is not a must. 14 15 16Alias creation 17============== 18 19Alias creation is done by 'magic' interface naming: eg. to create a 20200.1.1.1 alias for eth0 ... 21:: 22 23 # ifconfig eth0:0 200.1.1.1 etc,etc.... 24 ~~ -> request alias #0 creation (if not yet exists) for eth0 25 26The corresponding route is also set up by this command. Please note: 27The route always points to the base interface. 28 29 30Alias deletion 31============== 32 33The alias is removed by shutting the alias down:: 34 35 # ifconfig eth0:0 down 36 ~~~~~~~~~~ -> will delete alias 37 38 39Alias (re-)configuring 40====================== 41 42Aliases are not real devices, but programs should be able to configure 43and refer to them as usual (ifconfig, route, etc). 44 45 46Relationship with main device 47============================= 48 49If the base device is shut down the added aliases will be deleted too. 50