How to setup IP alias on bridged interface in Ubuntu

Question

How do I setup an IP alias on a bridge (br0) device on Ubuntu ?

If I wait for br0 to come up and then do

/sbin/ifconfig br0:0 192.168.10.1 netmask 255.255.255.0

then it works fine.

If however I add the following to my /etc/network/interfaces file, it does not work and the network fails to start:

auto br0:0
iface br0:0 inet static
   address 192.168.10.1
   netmask 255.255.255.0

At the moment, I have a script in /etc/network/if-up.d/bridge_alias that does this as follows:

#!/bin/bash

if [ "${LOGICAL}" == "br0" ] && [ "${PHASE}" = "post-up" ]; then
        echo -n "Starting br0:0 ... "
        /sbin/ifconfig br0:0 192.168.10.2 netmask 255.255.255.0
        echo "Done!"
fi

What is the right way of doing this though, just using the OS network config files ?

rlex · Accepted Answer · 2013-10-24T15:54:38.290

4

The only way you can do that is from ifconfig (or maybe ip addr add, but i haven't checked it against bridges). if-up.d is okay, but i recommend you use post-up in interfaces, like:

auto br0:0  
  iface br0:0 inet static  
  address 192.168.10.1  
  netmask 255.255.255.0  
  post-up /sbin/ifconfig br0:0 192.168.10.2 netmask 255.255.255.0

You can repeat post-up as much times as you want.

edited Oct 24 '13 at 15:54

answered Oct 24 '13 at 13:30

rlex

156
2

Thanks - didn't realise I could do that in a post-up command – Anonymouslemming Oct 24 '13 at 15:39

score 2 · Answer 2 · edited Jul 07 '17 at 06:08

Here is something I'm using, works in Debian 8 and Ubuntu 16.03:

auto lo
iface lo inet loopback

auto br1 
iface br1 inet static
    bridge_ports eth1 
    address  172.17.17.1
    netmask  255.255.255.0
    network  172.17.17.0
    broadcast 172.17.17.255
    post-up /usr/sbin/dhcpd 

auto br1:1 
iface br1:1 inet static
    address 172.17.17.2
    netmask  255.255.255.0
    network  172.17.17.0
    broadcast 172.17.17.255

How to setup IP alias on bridged interface in Ubuntu

2 Answers2

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