Apt-get on Ubuntu might not be working after fresh installation.
Linux system normally uses the http_proxy environment variable for the proxy setting.
Setting the http_proxy variable:
bash$ export http_proxy=http://<host>:<port>
If required login for your proxy server, specified it this way:
bash$ export http_proxy=http://<username>:<password>@<host>:<port>
you can add the above to your .bashrc file once it is working. (test using ping or apt-update)
