How does a Proxy Server manage different Protocols?

You can find a proxy server in many forms on the internet,but they all face similar challenges in how to handle the different protocols that are being used on the internet.

A proxy server typically operates at the Application layer of the OSI model and typically has two ways of handling protocols - either be proxied or tunneled.

A proxy operating at the Application we basically means that the proxy server actually understands what is happening. At this point we can do neat things like filter the protocol, perform logging and operate access control.

If a proxy doesn't understand a protocol however it will generally just tunnel this information between the client and the server. This relaying happens generally with any protocol that the proxy doesn't have specific support for it, examples are things like SSL protocols which are normally just tunneled by most proxies (but many don't support SSL at all) including many of the web based proxies you'll find on the internet.

Examples of protocols that do operate at the application level and which are truly proxied are things like HTTP and FTP, also Gopher

From http://www.codeghost.com/gopher_history.html

"Gopher is a protocol system, which in advance of the World Wide Web, allowed server based text files to be hierarchically organised and easily viewed by end users who accessed the server using Gopher applications on remote computers. Initially Gopher browsers could only display text-based files before developments such as HyperGopher, which were able to handle simple graphic formats though they were never used on a widespread basis as by this time the World Wide Web and its Hypertext Transfer Protocol (HTTP) were gaining in popularity, and had similar and more extensive functions"

So, the important thing to remember for privacy is that ever piece of data you send through the web browser while using a proxy, goes through that proxy server. Please ensure that it is secure and managed properly