What is a Proxy Server
A proxy server is a server that makes requests on behalf of a third party. Proxy servers are commonly used for web proxies. With a web proxy server, a client machine browses to a web page and passes the request to the proxy server. The proxy server then retrieves the web page on behalf of the client machine, and passes the content back to the client.
Web proxy servers are commonly used to separate machines on a private network from the internet, while still allowing web access.
Proxy servers can provide many benefits from a security point of view. This includes virus scanning all files that are downloaded. Logging all web browsing activity, blocking certain websites and providing user level access control.
Some proxy servers allow web responses to be cached. This is when the proxy server stores a local copy of a web page or image for a specific length of time. All further requests for the same page will result in the local cached file being returned, until the cached file is deemed to have expired. This can greatly reduce the internet bandwidth used by the machines behind the proxy server. It also increases the web browsing performance.
Reverse Proxy Servers
Instead of sitting between client machines and the internet, a reverse proxy server is a proxy that sits between a web server and the internet. In this configuration, the proxy server accepts requests from web clients and passes the request onto the web server.
Reverse proxy servers can be used to cache pages and images to reduce the load on web servers. They can also be used to separate web content and pass requests to different web servers.