Proxy-Based Filtering Software

Who Uses Proxy Based Filtering?

Proxy based filtering is commonly used by large organisations to introduce filtering policies for users and offers a high level of flexibility and granularity.  It does require that the organisation has a server with enough capacity to run effectively as this software can add additional loading on the system.

Disadvantages

Because a proxy server has to terminate web site requests and then regenerate them there is an amount of latency introduced in the data stream and thus performance is limited by available capacity.   The servers also change the source IP address of the web request from the user to their own IP which can cause problems with some traffic types.

Should ISPs Use Proxy Based Filtering?

For these reasons this sort of solution is not suitable for ISPs and carriers. 

An example of this type of filtering software is Websense. 

Bluecoat is an example of a company that offer an appliance with proxy filtering.  Using an appliance removes the requirement for a server but it still has the limitations of proxying in regards to performance, scalability and the changing of IP addresses on the web requests.