UPDATE December 27th: I’ve added a post which doesn’t need dconf-editor here.
Since Ubuntu 11.10, the proxy settings tab in the system settings have been changed, it’s no longer possible to enter your credentials in the proxy settings.
There’s a solution where you can edit these settings through dconf-tools:
Download and run dconf-tools in the terminal by executing these two lines of code:
sudo apt-get install dconf-tools dconf-editor
Within dconf-editor, goto “system > proxy” and change “mode” to manual.
Then select “use-same-proxy”
After that, go to “system > proxy > http”, enter your proxy information and select “enable”
Make sure ftp, https and socks have “0” (zero) on “port” and nothing on “Host” field
Everything should work fine now.
Update on October 23th with screenshots:
(Please note: you should change the blurred values)