Before you configure your new Squid server, set up the local web browser to use it for its web access. Doing so enables you to test your rules as you are working with the configuration file.
To configure Firefox, while Firefox is running in the foreground select Preferences from the Edit menu from the top panel of the Ubuntu desktop. From the dialog that appears, select the Advanced settings using the icon in the top row, and within Advanced, select the Network tab. Then click the Settings button next to Configure how Firefox connects to the Internet and select the Manual Proxy Configuration option. Check the box beneath it labeled Use the Same Proxy for All Protocols. Enter
127.0.0.1 in the HTTP Proxy box and
3128 as the ...