A proxy server receives, from multiple visitors of multiple client devices, a plurality of requests for actions to be performed on identified network resources belonging to a plurality of origin servers. At least some of the origin servers belong to different domains and are owned by different entities. The proxy server and the origin servers are also owned by different entities. The proxy server analyzes each request it receives to determine whether that request poses a threat and whether the visitor belonging to the request poses a threat. The proxy server blocks those requests from visitors that pose a threat or in which the request itself poses a threat. The proxy server transmits the requests that are not a threat and is from a visitor that is not a threat to the appropriate origin server.