Feisty Synaptic and Gnome language support proxy setting problem

You can configure apt to use a proxy, see the following forum post:-

http://ubuntuforums.org/showpost.php?p=541276&postcount=1006

If you are behind an authenticating proxy server then you may need to change the line in that guide which reads:-

http::proxy "http://172.16.1.71:8080/"

to something like:-

http::proxy "http://username:password@172.16.1.71:8080/"

Where "username" is your proxy username, and "password" is the password for the proxy.

If you are on a windows network using a proxy that uses NTLM authentication and you are a member of a domain then you may need to use:-

http::proxy "http://domain\\username:password@172.16.1.71:8080/"

You may need either one or two \ in there, I am not sure.

Thank you,

but i'm behind to an apt-cacher proxy for deb packages that cache my .deb packages, usually very well and it work fine.
It is on 192.168.1.50 answering on 3128 port and it work for me and my Feisty network pc's.
The apt-cacher proxy resolve the corporate user/password Squid (not NTLM) autentication, it work fine.

I have the follow row in all pc:
Acquire::http::Proxy "http://192.168.1.50:3128/";
into /etc/apt/apt.conf.d/proxy it usually works good.

apt-get updates and upgrade work fine from all pc.

I can't understand why i have problem only with downloading language packages.
I think is Synaptic that have the problem with the network configuration.
If i try to bypass proxy (i 'm sure i can) going out directly with Synaptic it always give me an error related to a proxy auth request, this is wrong.
I'm little confused because on all pc i have the same problem.

Thanks Berend De Schouwer, that solved my question.