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

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

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

add additional ipv4 addressess to the interface

1 Answers1