Binary package hint: update-manager
I am behind a firewall, but use an ubuntu mirror on the local network. Update-manager seems to ignore the automatic proxy configuration script (which should tell it to ignore the proxy for local addresses) and falls back upon the manual proxy configuration. (I know that it uses the manual config because I deliberately entered details of a separate proxy server in the manual fields to test this.) However, it also ignores the exclusion list entered under the "advanced" tab of the gnome proxy configuration dialogue.
This means the only way for me to bypass the proxy for the local mirror is to manually set gnome to use no proxy every time.
(BTW, the fact that there is no indication to the user that manual config is the fallback behaviour of apps that cannot use automatic config scripts is also rather confusing.)
a friends machine has an automatic proxy set up in system-
update-manager claimed did not show the upgrade from gutsy to hardy, even after checking for updates, and using the -c -d flags. neither did the do-release-upgrade script.
there was no error message or warning.
after selecting 'direct connection to internet' (the machine only use the proxy so that it can access IP restricted services), the update-manager found the update.