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.