By caching content, a proxy server acts as a go-between for clients and resources to improve security and speed up performance. For example, a client may connect to the proxy server, requesting a service (such as a file, connection, web page, or other resource) available from a different server. The proxy server evaluates the request according to its filtering rules. It may philtre traffic by IP address or protocol. If the philtre validates the request, the proxy provides the resource by connecting to the relevant server and requesting the service on behalf of the client.