There is a guide (untested by me) on how to setup a proxy if present and use DIRECT otherwise: http://askubuntu.com/questions/53443/how-do-i-ignore-a-proxy-if-not-available
Does this solve the problem you describe in this bug? ** Changed in: apt (Ubuntu) Status: New => Incomplete -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/827627 Title: apt should be able to use an opportunistic cache/proxy To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/apt/+bug/827627/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs