If you are like me behind a Microsoft ISA server proxy on a domain network or any other type of proxy, you will find problems getting the Linux applications Synaptic package manager or apt-get to work.
The best way I came across to solve this issue is to use a software called ntlmaps.
This application is a proxy software that allows you to authenticate via an MS Proxy Server using the proprietary NTLM protocol. This is useful when you start getting error “Error 407 Proxy Authentication Required” which drove me crazy the whole day!
I’m using Ubuntu as my Linux OS. If you were able to make Firefox work so you can go to http://packages.ubuntu.com/ , select your Ubuntu edition , browse all packages and look for ntlmaps, download it and install it.
After that open the file /etc/ntlmaps/server.cfg and make sure you fill the parameters correctly such as the Listening port (The port to use in the proxy) NT_HOSTNAME (Which is the Domain Controller’s computer name on the network) and NT_Domain.
After that configure the Network proxy to use your new proxy for example: 127.0.0.1:5865
Good luck 😉