Adding a second IP address to RedHat Linux Vs. 4.2
 

I have several servers in our branch offices running Red Hat Linux vs. 4.2 with kernel vs. 2.0.30. The software company that provided the servers does not want to upgrade to a newer version of Linux because their software may not run on it. I want to add a second IP address to this configuration for routing and management capabilities but I'm not sure if a second IP is capable of being added on this old a kernel. Can someone tell me for sure? If it is able to, please steer me in the right direction for configuration.

Thanks

If you want to add an interface for management, it's better to add a second physical card configured to be on your management network (not the same subnet as the original NIC!).

You should really put together a plan to test the vendor's hardware on a newer version of Linux. RH 4 is over a decade old and potentially has dozens of unpatched security vulnerabilities.

That version of RedHat has 2.6 kernel which allows multiple ip addresses per nic. You can assign a second network ip address on the same nic with command:

ifconfig eth0:1 192.168.1.1

Both addresses should be on the same network unless you have VLAN capable switches.

According to another source I have, you may be thinking of the newer enterprise version. This is the old original version 4.2 that's about 10 or 12 years old.

You're not going to be able to upgrade the kernel in place without breaking your userland interaction.

You can try using virtual interfaces on 2.0 kernel and see if it works. The worst that will happen is you will get an error message about that operation not being supported.