How to set routes?

Question

I use Ubuntu since 8.10 version and today I'm using Ubuntu 12.04 Server.
I am with difficult in to keep static routes on booting.
I usually put the route commands

/sbin/route add -net <IP>/<MASK> <GW> dev <ethX>

in /etc/rc.local or I create a file (named routes) inside directory /etc/network/if-up/, but I notice that on Ubuntu 12.04 it isn't working.

If I type the commands on shell, they work, but the same commands don't work when they are on my file.

I already tried to change the file name to other names thinking that my file name (routes) could be reserverd words from Ubuntu 12.04, but also not worked.
I notice also that command /sbin/ifconfig works, less the /sbin/route.

What changed on network set-up?

How can I to define routes on Ubuntu 12.04?

Answer 1

You can put static routes in /etc/network/interfaces:

auto eth0
iface eth0 inet static
      address 192.168.1.2
      netmask 255.255.255.0
      up route add -net 192.168.0.0 netmask 255.255.0.0 gw 192.168.1.1
      up route add -net 172.16.0.0 netmask 255.255.0.0 gw 192.168.1.1

Answer 2

You can try this (add it to /etc/network/interfaces), this is almost complete way for setting routes:

auto eth0
iface eth0 inet static
    post-up /sbin/route add -net 192.168.0.0 netmask 255.255.0.0 gw 192.168.1.1
    post-up /bin/mount -t nfs 192.168.0.203:/motd/ /motd/

Answer 3

I found very often that the correct place to define a static route is in /etc/network/interfaces, it is ok if you are going to globally restart the network with /etc/init.d/networking restart for example. But if you are going to use ifdown and ifup to individually shutdown an interface, ifup will end with the error:

ifup eth1

RTNETLINK answers: File exists
Failed to bring up eth1.

Because of it tries to define a route but it is already defined. The interface will be up anyway but, ifup will not update /run/network/ifstate so next time you will us ifdown you will not able to do it unless you use the --force flag.

To make ifup to continue configuring even if routes are already defined, you can use this format when defining routes in /etc/network/interfaces

up ip route add 172.16.0.0/24 via 192.168.10.1 || true
up ip route add 192.168.0.0/16 via 192.168.10.1 || true

This way you will have the warning in the output but the interface configuration will be completed

ifup eth1

RTNETLINK answers: File exists
RTNETLINK answers: File exists
ssh stop/waiting
ssh start/running, process 18553