Check if you're behind a Proxy Server

By using a proxy server, your IP address will be hidden from websites and other web services that you use. Any web resource you access can gather personal information about you through your IP address. Anonymous proxy servers hide your IP address thereby saving you from vulnerabilities concerned with it.

Here are the variables sent by the server

Setting up Web Proxies in Mozilla Firefox

• Go to Preferences
  (in Windows, it is Tools | Options | Preferences and Linux, it is Edit | Preferences).
• Click on General tab on the left and the button labelled Connection Settings.
• Select Manual Proxy Connection and enter the HTTP proxy server address and port number.
• Check if you are behind the proxy by visiting this.

Setting up Web Proxies in Internet Explorer

• Click on Tools | Internet Options | Connection.
• Click on the button labelled LAN Settings.
• Under Proxy Server, check the box corresponding to "Use a proxy server for your LAN".
• Enter the address and port from the list below.
• Click on OK and then OK again and you should be back to your normal Internet Explorer browser window.