In order to connect a ubuntu linux vm to a microsoft proxy server, several steps are involved to produce a working connection.
Several ubuntu versions (maybe a new version can do this automatically) are not able to connect to such a proxy without further tweaking.
The software which is needed to perform the NTLM authentication is named Cntlm.
It can be found here:
Download the latest version, untar and compile it using the default settings:
make && make install
You will be asked for the password and if the command performs successfully, a authentication mechanism und a password hash will be displayed.
Edit the file /etc/cntlm.conf and change the following values:
The Password and second Proxy entry should be commented out.
Change/add the following values in the file below:
Save the file and start the cntlm command as root. The program will listen to port 3128 by default.
Change the Ubuntu Settings:
to use a manual proxy configuration and use 127.0.0.1 with port 3128 as proxy for all connections. The user/password should be empty, since the cntlm does the authentication. Apply the settings system-wide and you can now use apt, wget and other programs requiring internet connection.