After upgrading my backup server from the previous LTS release (Lucid) to the new one, the config which backs up /etc on localhost was failing. It was failing because pings to localhost were failing. This is no good – localhost should be pingable. :) Ultimately, this is because IPv6 is enabled by default now. I don’t use IPv6 on my internal network, mostly because it’s new and scary and I don’t like change. Or because I just don’t need it. So, here’s how to disable IPv6 on your Ubuntu 12.04 / Precise box: