I use this more then any other VPN to the office. First you will need to run the following:

ssh -C -D 3128 username@domain.com

Once you authenticate with the server you will be able to open Firefox and change your proxy setting. To do so open Firefox and click the "3 bar" icon for the Menu.

firefox-settings

Click on the gear for Preferences.

firefox-preferences

Click Advanced, then Network.

firefox-advanced firefox-network

Click on Settings. Once there change the setting from "No proxy" to "Manual proxy configuration". Then enter under SOCKS Host "localhost" and port "3128"

firefox-network-settings

Once done click "Ok" and navigate to your site within the network.