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Documentation / networking / alias.txt


Based on kernel version 4.16.1. Page generated on 2018-04-09 11:53 EST.

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