Running SuSE 8.1:

Somehow, my loopback disappeared. AFAIK, I didn't change anything -- one day it was there, and the next day, it wasn't.

What do I need to do to get the loopback working again?

TIA!

This will normally do it, assuming that it's configured properly:

Thanks! I'll try that.

How can I make sure that lo comes up automatically on bootup again, or will that do it?

No, that will only bring the interface up.

Firstly, make sure that your network service is configured to come up in your default runlevel. That is, you should have a file called /etc/rc.d/rc5.d/Sxxnetwork where xx is a two-digit number. This file should be responsible for configuring and starting the network interfaces. If not, then create it; it's a symbolic link to /etc/rc.d/network and the two-digit number is one less than the number of Sxxsyslog in the same directory.

If the link exists, then the easiest way to fix this is to put that command in your /etc/rc.d/boot.local file. I think that should fix it.

Thanks. I haven't had the chance to try that yet, but I will.

Doing "ifup lo" returns a complaint about missing config for lo, for some reason.

Check to see if the file /etc/sysconfig/network/ifcfg-lo exists
It should contain the following:

# Loopback (lo) configuration
IPADDR=127.0.0.1
NETMASK=255.0.0.0
NETWORK=127.0.0.0
BROADCAST=127.255.255.255
STARTMODE=onboot

Mark

It's working again! The file /etc/sysconfig/network/ifcfg-lo had disappeared somehow -- not as a result of anything I did AFAIK, because I haven't changed any settings on this machine in months. Once I wrote a new ifcfg-lo file and re-enabled the network config in the Runlevel Editor, everything was back to normal.

Thanks to rjlee and cyprinus for your help!