I know this question has been asked before but my scenario is slightly different.
I'm able to connect to the internet via Firefox and Skype. However all other applications are unable to.
I'm operating behind a school proxy, and I'm running Kubuntu 14.04 (installed last night). I have set up my proxy settings to manual and configured them correctly. I also tried exporting the environment variables but its not working.
sudo env http_proxy=example.myproxy:3128 apt-get install gimp
I get the error:
Failed to fetch http://archive.ubuntu.com/ubuntu/pool/universe/d/dvgrab/dvgrab_3.5-2_amd64.deb Cannot initiate the connection to 3128:80 (0.0.12.56). - connect (22: Invalid argument).
It's a laptop, and I connect to various networks, so setting the variables to be persistent is not a desirable option.
On WI-FI though all works well (no proxy)