APT Proxy

An APT proxy is a server which the other machines using APT (that is, any Ubuntu or other Debian-based machines) contact for updates instead of calling the mirror directly.

Since APT uses HTTP transport by default (it can use other transports, but that's a subject for another day) an APT proxy is basically a specialized caching HTTP proxy. As such, it's perfectly possible to use a general purpose http proxy such as Squid. We already have Squid set up, though it is not yet configured. Once we have some information as to its performance we can make a decision as to whether to use apt-cacher, approx or such like instead.