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I have an interface eth0, and I wish to give it an extra virtual IP. I achieve this by the following:

ifconfig eth0:0 ip.address.goes.here netmask subnet.address.goes.here

This works fine, however, when I reboot, this is lost.

I have tried editing /etc/network/interfaces to add the following:

auto eth0:0 iface eth0:0 inet static
    address ip.address.goes.here
    netmask subnet.address.goes.here

However, upon rebooting, the static ip for eth0 is loaded fine, but, the eth0:0 virtual IP is not loaded at all.

So, how can I permanently add the eth0:0 virtual IP?

wilhil
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  • Possible duplicate: http://askubuntu.com/questions/45086/how-to-add-an-ip-alias-on-a-bridged-interface .. this is for a bridge, but change br0 to eth0 and the method is the same. – Caesium Nov 27 '11 at 13:54

2 Answers2

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Instead of that eth0:0 business, you should do this:

  • Configure your (one) static IP address in /etc/network/interfaces as you normally would:

    # The primary network interface
auto eth0
iface eth0 inet static
address 192.168.0.201
network 192.168.0.0
netmask 255.255.255.0
broadcast 192.168.0.255
gateway 192.168.0.1

  • Add another IP to this interface by adding this right after the above:

    up /sbin/ip addr add 192.168.0.203/24 dev eth0
down /sbin/ip addr del 192.168.0.203/24 dev eth0

  • The complete file should look like this

Now, if you check what IP addresses are configured by running ip addr show, both will show up:

2: eth0:  mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 08:00:27:1d:fa:0b brd ff:ff:ff:ff:ff:ff
    inet 192.168.0.201/24 brd 192.168.0.255 scope global eth0
    inet 192.168.0.203/24 scope global secondary eth0

My thanks to Lekensteyn for pointing me in the right direction. Every site on the internet just talks about eth0:0 for a secondary IP address. This seems like the proper way to do it.

Stefano Palazzo
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    Yes, ifconfig has been deprecated in favour of the `iproute2` suite (the ip command). `ifconfig` will never leave my muscle memory though. Also **important** of note, `ifconfig` cannot see address aliases added by `iproute2`! (this doesn't make them work any less well). – Caesium Nov 27 '11 at 14:21
  • Great! @Caesium that's along the lines of what I suspected. Good to know I wasn't completely misremembering. :) – Stefano Palazzo Nov 27 '11 at 14:23
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    @Caesium I am a little confused, I tried manually typing "ip addr add 192.168.0.40/24 dev eth0 label eth0:51" which is garbage information - and, it showed up in ifconfig just fine? ... Don't suppose you fancy coming in to chat to talk a little more!? – wilhil Nov 27 '11 at 14:25
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    @wilhil, ooh! you taught me something, if you add a label it *does* show up in ifconfig! If you don't use a label it doesn't. Thanks :) – Caesium Nov 27 '11 at 14:32
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    The pastebin entry posted is no longer available: `The Paste you are looking for does not currently exist.` – saji89 Mar 20 '14 at 04:43
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If you want to do things the "traditional" way, the relevant part of /etc/network/interfaces should look like:

auto eth0:0
iface eth0:0 inet static
    address ip.address.goes.here
    netmask subnet.address.goes.here

instead of this, where you made a mistake:

auto eth0:0 iface eth0:0 inet static
    address ip.address.goes.here
    netmask subnet.address.goes.here
Alastair Irvine
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  • After adding, execute: `ifup eth0:0` to start it manually. You can check if its working by executing: `netstat -rn` – lepe Aug 17 '15 at 04:16