|
Introduction:
In small or large network environments there is usually a need to cache HTTP information to increase web site access times, reduce overall bandwidth usage and help decrease bandwidth costs. In order to attain these goals a network administrator would use a proxying/caching server software to store recently visited web pages in a cache on their own network.
How it works:
The way a proxy works is as follows. The client computers have settings in the web browser that are set to use the proxy server on their network. When the client requests a web page(For instance www.opensite.org), the caching server will check if it has that particular page. If it does it will serve the page to the client immediately from its own disk. If the page is not cached on the proxy server, the proxy server will request the page for the client, store the page information locally and then finally give the requested information to the client. This eliminates the need for this page to be accesses directly the next time a different client requests the same page.
Transparent Proxying
If a network administrator cannot get the settings out the all the client machines or wants to enforce the use of the proxy on the network then they can implement what is called a transparent proxy. In this instance the server that is running the proxy software is usually also the default gateway for the network. All HTTP traffic that is requested is redirected through the caching server via firewall rules.
Software Products:
On unix/linux based server systems the most popular product is Squid (http://www.squid-cache.org/). On Windows platforms Microsoft ISA server (http://www.microsoft.com/isaserver/) is fairly dominant.
|