Although web proxy servers are evolving all the time, there are some specific properties that all proxies should share.
Here’s a selection of the most important fundamentals that you should find in a proxy:
- Transparency; proxies should not affect the end result of any communication. A user or a server should get the same response whether the connection was direct or routed through a proxy server. The only exception to this situation is if the proxy is configured to do any filtering or rerouting, otherwise the server should be completely transparent.
- Control; the client should be in control of whether the proxy is used or not. Although the decision should be made on the client, this can be enforced either through browser configuration or group policy settings in a windows environment. This situation is common among corporate configuration of client PCs, ensuring that internet access is only accessible via the proxy ensures some control and protection against virus and malware.
- Destination unaffected; the destination server is not affected by any proxy which exists. The destination server should ideally be completely unaware of the existence of the proxy.
Probably the most important concept in these three properties of a proxy is that of transparency. There is really no need for either the client or server end of the connection to be aware of the proxy if it is configured correctly. If a proxy does not interfere with the communication at all, this should also ensure that speed and performance is optimized. Here’s an example of a proxy being. however this video which actually demonstrates a residential vpn service which relays the connection through an intermediate server depending on the destination.
In fact speed is often one of the primary reasons for using a proxy server, when it is enabled in a caching mode. This enables the server to store copies of often requested web pages and resources and serve them directly to client responses. This reduces network traffic and can reduce the time needed to service a client request.
The functions of access control and filtering will of course introduce an overhead to the connection but this is often considered a worthwhile impact. A proxy server can be an important barrier to protect an internal network from outside attacks and viruses. Most organisations will ensure that no direct access is allowed through the external firewall except via the proxy, this ensures that everything is funneled through a single point and allows logging and monitoring too.