[Gllug] Two IPs and one NIC

Bruce Richardson itsbruce at workshy.org
Wed Mar 23 08:39:10 UTC 2011

On Tue, Mar 22, 2011 at 10:31:34PM +0000, Walter Stanish wrote:
> > Dumb question of the day. Is it possible for a box two have two ip addy's one one NIC?
> Yes, IIRC this is referred to as aliasing.

It's called aliasing if you add an alias along with the ip address, as
you have to with ifconfig, as per your example.

> Generally you can implement this old-style by going 'ifconfig eth0:1

But the alias is not essential.  If you use the ip tool, you can just do

	ip address add <address/netmask> dev <ifname>

Unless you add an alias, though, ifconfig won't see or work with the
extra address (and some other reporting/monitoring tools may not see it
either).  This may or may not matter to you.  With the ip tool, that
would mean changing the line to

	ip address add <address/netmask> dev <ifname> label <label>

If I'm manipulating ip addresses and routes directly, I find the ip tool
much more precise and flexible than the legacy tools (ifconfig, route
and so on).  It offers a common syntax for managing addresses,
interfaces, routes, policy routing rules and a few other handy things.
The iproute suite of tools is available for any of the distros and
installed by default on many of them, these days.


If the universe were simple enough to be understood, we would be too
simple to understand it.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 204 bytes
Desc: Digital signature
URL: <http://mailman.lug.org.uk/pipermail/gllug/attachments/20110323/d30bbd25/attachment.pgp>
-------------- next part --------------
Gllug mailing list  -  Gllug at gllug.org.uk

More information about the GLLUG mailing list