Editing Proxy server (section)

====Issues====
The diversion or interception of a TCP connection creates several issues. First, the original destination IP and port must somehow be communicated to the proxy. This is not always possible (e.g., where the gateway and proxy reside on different hosts). There is a class of [[Cross-site scripting|cross-site attacks]] that depend on certain behaviors of intercepting proxies that do not check or have access to information about the original (intercepted) destination. This problem may be resolved by using an integrated packet-level and application level appliance or software which is then able to communicate this information between the packet handler and the proxy.

Intercepting also creates problems for [[HTTP]] authentication, especially connection-oriented authentication such as [[NTLM]], as the client browser believes it is talking to a server rather than a proxy. This can cause problems where an intercepting proxy requires authentication, and then the user connects to a site that also requires authentication.

Finally, intercepting connections can cause problems for HTTP caches, as some requests and responses become uncacheable by a shared cache.