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1 | .. SPDX-License-Identifier: GPL-2.0 |
2 | ||
3 | =========== | |
4 | IP-Aliasing | |
5 | =========== | |
6 | ||
7 | IP-aliases are an obsolete way to manage multiple IP-addresses/masks | |
8 | per interface. Newer tools such as iproute2 support multiple | |
9 | address/prefixes per interface, but aliases are still supported | |
10 | for backwards compatibility. | |
11 | ||
12 | An alias is formed by adding a colon and a string when running ifconfig. | |
13 | This string is usually numeric, but this is not a must. | |
14 | ||
15 | ||
16 | Alias creation | |
17 | ============== | |
18 | ||
19 | Alias creation is done by 'magic' interface naming: eg. to create a | |
20 | 200.1.1.1 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 | ||
26 | The corresponding route is also set up by this command. Please note: | |
27 | The route always points to the base interface. | |
28 | ||
29 | ||
30 | Alias deletion | |
31 | ============== | |
32 | ||
33 | The alias is removed by shutting the alias down:: | |
34 | ||
35 | # ifconfig eth0:0 down | |
36 | ~~~~~~~~~~ -> will delete alias | |
37 | ||
38 | ||
39 | Alias (re-)configuring | |
40 | ====================== | |
41 | ||
42 | Aliases are not real devices, but programs should be able to configure | |
43 | and refer to them as usual (ifconfig, route, etc). | |
44 | ||
45 | ||
46 | Relationship with main device | |
47 | ============================= | |
48 | ||
49 | If the base device is shut down the added aliases will be deleted too. |