add additional ipv4 addressess to the interface

Question

I faced a small problem when assigning multiple IPv4 addresses to the interface. I added 2 IPv4 addresses by following these steps :

first, I added the 2 IPv4 addresses using these command-lines:
```
#sudo ip address add  10.0.0.21/24 dev eth1
#sudo ip address add  10.0.1.21/24 dev eth1
```
To check the result I typed the following command-line :
```
#ip address show eth0.
```

Second, to make these configurations permanent, I edited the /etc/network/interfaces file by adding specific configurations and now it looks like this:

auto eth1 
iface eth1 inet static
       address 10.0.0.21
       netmask 255.255.255.0
       gateway 10.0.0.1

auto eth1 
iface eth1 inet static
       address 10.0.1.21
       netmask 255.255.255.0
       gateway 10.0.1.1

Finally, to activate these settings without a reboot , I used the
ifdown/ifup by typing:
```
#sudo ifdown eth1 && sudo ifup eth1.
```

The first problem is when I used the ifdown/ifup command , I got this notifications:

ifdown: interface eth1 not configured
RTNETLINK answers: File exists
Failed to bring up eth1.

whereas I updated the /etc/network/interfaces so, normally it may to recognize the interface.

The second problem is when I rebooted my machine all the setting were lost. thank you

two gateways? that will be an issue as that adds two default routes. Are you sure you know what you want? — gertvdijk, Jul 22 '15 at 11:38
I would like to assign 2 ipv4 addresses to eth1 because I only have one interface , there is an another solution which is using the alias (eth1:0) but I find in the INTERNET that you should assign multiple ipv4 addresses like I did and here is the link http://askubuntu.com/questions/547289/how-can-i-from-cli-assign-multiple-ip-addresses-to-one-interface — rochdi bouslama, Jul 22 '15 at 11:42

2707974 · Accepted Answer · 2015-07-23T07:21:12.527

1

To add secondary ip on interface you must create sub-interface.

In you case eth1:1

auto eth1 
iface eth1 inet static
       address 10.0.0.21
       netmask 255.255.255.0
       gateway 10.0.0.1

auto eth1:1 
iface eth1:1 inet static
       address 10.0.1.21
       netmask 255.255.255.0
       gateway 10.0.1.1
       metric 20

Based on comment I edit answer and add metric to interface eht1:1. This mean that gateway on eth1 will be primary routing decision. You can add metric to eth1 if you wish eth1:1 be primary.

Edit 2

I found more people which have the same problem and solution is:

auto eth1 
iface eth1 inet static
       address 10.0.0.21
       netmask 255.255.255.0
       gateway 10.0.0.1
       up ip addr add 10.0.1.21/24 dev eth1 label eth1:1
       down ip addr del 10.0.1.21/24 dev eth1 label eth1:1
       up ip route add 10.0.1.0/24 via 10.0.1.1 dev eth1:1 metric 20
       down ip route del 10.0.1.0/24 via 10.0.1.1 dev eth1:1 metric 20

edited Jul 23 '15 at 07:21

answered Jul 22 '15 at 11:34

2707974

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two gateways? that will be an issue as that adds two default routes. Which one wins? ;) Oh, that's an issue in the question already... sorry – gertvdijk Jul 22 '15 at 11:37
I edit answer :) – 2707974 Jul 22 '15 at 11:43
do I have to type the ifdown/ifup command for activating the change ? – rochdi bouslama Jul 22 '15 at 11:51
sudo service networking restart – 2707974 Jul 22 '15 at 11:52
stop: Job failed while stopping start: Job is already running: networking – rochdi bouslama Jul 22 '15 at 11:55
the easiest is to reload pc – 2707974 Jul 22 '15 at 11:58
the ipconfig show me only eth1 so that eth1:1 were removed after rebooting – rochdi bouslama Jul 22 '15 at 12:06
Try with sudo ifconfig eth1:1 up – 2707974 Jul 22 '15 at 12:11
If steal can not have success you can add secondary ip with command sudo ifconfig eth1:1 10.0.1.21 netmask 255.255.255.0 and add route with command sudo route add -net 10.0.1.0/24 gw 10.0.1.1 dev eth1:1 metric 20 – 2707974 Jul 22 '15 at 12:16
You have Edit 2 in my answer – 2707974 Jul 23 '15 at 07:21

add additional ipv4 addressess to the interface

1 Answers1