Network -> Network Proxy -> Apply System Wide does NOT update "/etc/apt/apt.conf"

[Ramin.Honary]

When I bring my Ubuntu laptop to work, I must tell it to connect to the proxy server. To do this, I go to the "Network" pane, then the "Network Proxy" sub-pane. Under "Method" I select "Automatic" and enter the correct "Configuration URL". Then I press "Apply System wide". My web browser now can connect to the Internet. However, applications like "Update Manager", and "Ubuntu Software Center", and even "apt-get" in the command line fail to communicate with ANY package repository servers. Checking "/etc/apt/apt.conf", I see the file is empty.

To reproduce this issue:
1. With a computer that does not connect to the Internet via proxy, isolate the computer behind a firewall which forwards all Web traffic (HTTP, HTTPS, FTP) to a content-filtering proxy server.
2. In gnome-control-center, go to Network -> Network Proxy, and set the method to "Automatic", filling in the correct URL for the proxy configuration file. The same problem seems to occur if you configure the proxy settings manually.
3. Press the "Apply system wide" button.
4. Open "Update Manager" and press "Check" and/or "Install Updates". FAILS -- package updates appear to begin to download, but eventually times-out and reports an error.
5. Check "/etc/apt/apt.conf", it should be empty (or unchanged by gnome-control-center).

Work-around:
As a root user, modify "/etc/apt/apt.conf" by hand with content like:
 Acquire::http::proxy "http://proxy.serv.org:8080/";
 Acquire::https::proxy "https://proxy.serv.org:8080/";
 Acquire::ftp::proxy "ftp://proxy.serv.org:8080/";
 Acquire::socks::proxy "socks://proxy.serv.org:8080/";

ProblemType: Bug
DistroRelease: Ubuntu 11.10
Package: gnome-control-center 1:3.2.0-0ubuntu6
ProcVersionSignature: Ubuntu 3.0.0-12.20-generic-pae 3.0.4
Uname: Linux 3.0.0-12-generic-pae i686
ApportVersion: 1.23-0ubuntu3
Architecture: i386
Date: Fri Oct 21 13:22:24 2011
ProcEnviron:
 LANGUAGE=en_US:en
 PATH=(custom, user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: gnome-control-center
UpgradeStatus: Upgraded to oneiric on 2011-10-14 (6 days ago)
usr_lib_gnome-control-center:
 deja-dup 20.0-0ubuntu3
 gnome-bluetooth 3.2.0-0ubuntu2
 indicator-datetime 0.3.1-0ubuntu1

[Phil. V (philip.v)]

Thank you for your report. This has already been reported in bug 877088, so I am marking this as a duplicate. Your report was quite thorough though, so if you think you can add something to that report please do so.