Hello I need to find out how to enable a system wide proxy in xubuntu 10.10
Whilst the the other answers are good & ok (for terminal/bash prompts), in my opinion the correct place to add these are
gksu then add:
http_proxy="http://user:password@proxyserver:port" https_proxy="http://user:password@proxyserver:port" ftp_proxy="http://user:password@proxyserver:port"
Very similar but for those who run everything from within a term then yes the other answers will give results but for those in GUI land would be better off adding the above line to the environment file for full correct system wide usage.
there is a graphical tool called UbProxy, that sets the whole systema proxy, via a graphical interface (GUI). The only problem for me, was I have to log out my user and log in again to load the config. Is very simple to use. https://code.google.com/p/ubproxy/