Using Nginx as a Reverse Proxy to Get the Most Out of Your VPS

According to Ubuntu Geek:

Using Nginx as a reverse proxy is great for a few reasons. Firstly it handles static content very well. It is able to handle the requests and serve static content much faster in our tests and this has cut our page load time in about half (using YSlow with a clear cache). The memory footprint of Nginx is very small so this extra speed increase is worth every megabyte, in this case .6 megabytes of our total ram on a 540 megabyte server. Secondly, it allows for quick and easy migration of your Apache services to another server. Through the config files you are able to specify an IP of your server and a port. If your apache server is taking a pounding it wouldn’t be difficult to move it to another server and just change the proxy IP to your now remote server.

According to Wikipedia:

A reverse proxy or surrogate is a proxy server that is installed in a server network. Typically, reverse proxies are used in front of Web servers. All connections coming from the Internet addressed to one of the Web servers are routed through the proxy server, which may either deal with the request itself or pass the request wholly or partially to the main web servers.

A reverse proxy dispatches in-bound network traffic to a set of servers, presenting a single interface to the caller. For example, a reverse proxy could be used for load balancing a cluster of web servers. In contrast, a forward proxy acts as a proxy for out-bound traffic. For example, an ISP may use a proxy to forward HTTP traffic from its clients to external web servers on the internet; it may also cache the results to improve performance.

There are several reasons for installing reverse proxy servers:

• Security: the proxy server may provide an additional layer of defense by separating or masquerading the type of server that is behind the reverse proxy. This configuration may protect the servers further up the chain - mainly through obfuscation.
• Encryption / SSL acceleration: when secure websites are created, the SSL encryption is sometimes not done by the Web server itself, but by a reverse proxy that is equipped with SSL acceleration hardware.
• Load distribution: the reverse proxy can distribute the load to several servers, each server serving its own application area. In the case of reverse proxying in the neighborhood of Web servers, the reverse proxy may have to rewrite the URLs in each webpage (translation from externally known URLs to the internal locations).
• Caching: A reverse proxy can offload the Web servers by caching static content, such as images, as well as dynamic content, such as a HTML-page rendered by a content management system. Proxy caches of this sort can often satisfy a considerable amount of website requests, greatly reducing the load on the central web server; another term is Web accelerator. This technique is also used for the Wikipedia servers.
• Compression: the proxy server can optimize and compress the content to speed up the load time.
• Spoon feeding: a dynamically generated page can be produced all at once and served to the reverse-proxy, which can then return it to the client a little bit at a time. The program that generates the page is not forced to remain open and tying up server resources during the possibly extended time the client requires to complete the transfer.