James Harper writes:
If the reason for installing Squid is for caching deb's then you'll be much better off with apt-cacher.
I've had bad experiences with the two older apt-specific partial repo caching tools (apt-cacher and another one, I forget the name); IIRC they were vulnerable to injection from the LAN, and this would regularly happen by accident if >1 distro was used (e.g. ubuntu and debian both had foo-1.0-1 but with different checksums). IIRC last time this came up, a new one had recently come out (apt-cacher-ng?) which somebody said fixed all the problems. I switched to debmirror for my own needs, and it has worked flawlessly. Obviously it's not an option for the OP -- IIRC it typically pulls down a couple of hundred MB per week. Agree that apt-cacher or similar is easier and smarter than trying to replicate functionality in squid.