Ubuntu Linux: Creating ethernet alias for eth0 network device

by on June 17, 2006 · 25 comments· LAST UPDATED May 2, 2008

in , ,

Q. I am using Ubuntu Linux and I would like to know how to create alias for eth0 so that I can have multiple IP address?

A. To create alias for eth0 use ifconfig command. It is use to configure a network interface and aliases.

Assuming that your eth0 IP is 192.168.1.10 and you would like to create an alias eth0:0 with IP 192.168.1.11. Type the following command:

sudo ifconfig eth0:0 192.168.1.11 up

OR

sudo /sbin/ifconfig eth0:0 192.168.1.11 up

Verify that alias is up and running using following two command(s):

/sbin/ifconfig
ping 192.168.1.11
ping your-getway-ip

Permanent configuration

Your ethernet configuration is located in a file called /etc/network/interfaces. If you reboot system you will lost your alias. To make it permanent you need to add it network configuration file:

gksudo gedit /etc/network/interfaces

OR

sudo vi /etc/network/interfaces

Append the following configuration:

auto eth0:0
iface eth0:0 inet static
name Ethernet alias LAN card
address 192.168.1.11
netmask 255.255.255.0
broadcast 192.168.1.255
network 192.168.1.0

Save the file and restart system or restart the network:

sudo /etc/init.d/networking restart

Please note that you can also use graphical tools located at System > Administration > Networking menu. Or use the following GUI tool to setup aliases, hostname, dns settings etc:

sudo network-admin

If you want more network aliases, use eth0:1, eth0:2, eth0:N (max upto 254).

See also:

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{ 25 comments… read them below or add one }

1 kotnik June 18, 2006 at 12:15 am

/sbin/infconfig

There’s no such command. Fix the typo ;)

Reply

2 Juan Carlos Lau March 19, 2013 at 11:58 pm

Hello,

I’m having a strange problem when adding eth0:2 to /etc/network/interfaces, when I try and restart the networking service the machine tries to reload the configuration and gets stuck there, the only way to bring networking back is removing the eth0:2 instances from the file and restarting (service restart won’t work after this happens the first time)

If I simply bring up eth0:2 temporarily it doesn’t give me any problems.

Any ideas?

Thanks!

Reply

3 nixCraft June 18, 2006 at 11:26 am

kotnik,

Err…

thanks for heads up :)

Reply

4 Cloudless August 4, 2006 at 8:20 am

Thank you so much for this guide! It is easy to understand.

Reply

5 Tamil December 28, 2006 at 11:08 am

simple and good guide. Thank you.

Reply

6 Alex January 28, 2007 at 6:23 am

What if you don’t use a permanent ip address and
rely on DHCP to assign the IP address?

Is this correct?
sudo ifconfig eth0 up

Do I need to setup dhcp?

Reply

7 jusdur August 8, 2007 at 3:12 am

what does mean this line:
name Ethernet alias LAN card

i look into man interfaces, but can’t found about name syntax

thx

Reply

8 Zulqarnain November 27, 2007 at 7:53 am

i solve my problem of multi addresses.

Reply

9 Jayesh Sharma July 16, 2008 at 10:50 am

Hi All,
This is a very good site to linux learner.But how can i post my query to get resolution.

Reply

10 nixCraft July 16, 2008 at 11:14 am
11 Alex October 3, 2008 at 12:36 pm

When creating an alias, must it be in the same subnetwork?
To explain better, if my ip address id 1.1.1.1/255.255.255.0, the alias must be 1.1.1.x or can it be 2.x.x.x?

thanks

Reply

12 Manu Ignatius November 25, 2008 at 2:08 am

This link might be somewhat useful for aliasing an interface using programming.
Link

Reply

13 Gaurav Pruthi January 22, 2009 at 5:38 am

Why we can’t use more than 254 aliases on a NIC?
If i am using 2 NICs in my box, will the max. limit be 508?

Reply

14 Download Free Photos August 31, 2009 at 7:42 am

Hello,

Can I manually add IP to /etc/network/interfaces ?
Can someone post an example of multiple IP addresses on one NIC ?

thanks

Reply

15 Ross Sutherland September 1, 2009 at 11:20 am

Hell there. I am a new Linux user, more specifically Ubuntu. I was confused what was meant be the following line – “name Ethernet alias LAN card”. Is this the physical device name or just eth0?

Any help with this would be great thanks.

Reply

16 Ross Cooney June 14, 2010 at 7:38 pm

Thanks for the helpful tip.

Reply

17 Alexis Wilke November 20, 2010 at 6:59 am

That is exactly what I have in my file… including the auto eth0:0. However, it looks like the auto is not that automatic on a reboot. Have you had problems on a reboot? Wondering because I’ve seen many people running in the problem of the 2nd IP disappearing after the machine is restarted.

Thank you, Alexis

Reply

18 Anonymous April 21, 2011 at 12:39 pm

I have the same problem as Alexis Wike, Did anyone come up with a solution for this. After reboot the eth0:0 does not comeup. The auto eth0:0 line is there in the file but it seems that it does nothing. Thanks

Reply

19 Mitter Singh Thakur September 16, 2011 at 10:24 am

Hi all,

Thanks!

Can you please tell me why there is limit to create an alias for NIC?

How many IP’s we can assign to a single NIC any Why???

regards,
Mitter Singh Thakur
System Admin
+91-7737603000 | +91-8890152367 | mitter1989@gmail.com

Reply

20 Alexis Wilke September 20, 2011 at 6:22 am

Mitter,

Yes. The limit is something like 254. It one byte. 0 and 255 cannot be used or something like that.

Alexis

Reply

21 Michael December 18, 2011 at 4:34 am

The reason you may be having problems w/ AUTO on an alias is that you are not allowed to use anything other than the default subnet for the ip range in question.

(Example: 10.x.x.x uses a default subnet of 255.0.0.0) If you try to assign any other subnet mask to the aliased ip, it won’t let you, and will take down the interface instantly. (Also true if you use ifconfig to assign the netmask).

Kind of ruins the point needing things like a server w/ several 10.x.x subnets, and forces one to use 192.168 addresses for 255.255.255.0.

Which would be fine if one didn’t already have a complex subnetted 10.x.x.x set of ranges in place because 192.168 doesn’t have enough subnets.

Really annoying that.

Reply

22 Valdemar August 10, 2012 at 5:49 pm

Just big thanks!!! Ctrl+D

Reply

23 Qui September 23, 2013 at 12:10 pm

Hi , i want to know how you sure max alias is 254 ??

Reply

24 Alexis Wilke September 23, 2013 at 9:20 pm

Qui,

It looks like the answer changed when Linux 2.2 came out. So there is no real limit (4 billion, 2 power 64 minus 1) but having too many will slowing down your system and your hardware is not unlikely going to have a limit of its own.

Source:

http://superuser.com/questions/231656/what-is-the-maximum-number-of-ips-that-can-be-assigned-to-a-given-computer

Reply

25 Yan Adam January 13, 2014 at 4:16 pm

This thread is a little stale I guess but it’s the closest I could find…

For those having issues with their aliases not coming up automatically on reboot, I’ve discovered that if the “root” interface ethx with no alias is not brought up, the aliases do not get configured.

I fixed this by adding this lone entry only to my /etc/network/interfaces :
auto ethx

This worked under Ubuntu 12.04 at least.

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