The following was done to allow Ubuntu 10.10 access to repositories through firewall, confirmed to work for Ubuntu 12.04
1. Update proxy configurations
1.1. System, Preferences, "Network Proxy", "Manual Proxy Configurations", "Use the same...", "Apply System Wide..."
1.2. System, Administration, "Synaptic Package Manager", "Settings", "Preferences", "Network", "HTTP Proxy:"
2. edit the following file: /etc/apt/apt.conf as sudo su
You should already see the proxy settings from previous steps; however, it is missing your credentials, these need added and the appliance needs restarted.
Format is as follows:
Acquire::http::proxy "http://user:pass@proxy.xxxx.xxxx:port";
3. You will need to restart before these changes start working
Note: Do not bother editing /etc/bash.bashrc it does not help anymore