[vikarti]

This looks related to some other problem: - There is Alice's server which provide service X - There are clients like Bob who needs this service. - There is Mallory who thinks clients doesn't need such service. Mallory have significant resources (more than Alice or Bob). - Mallory thinks it's ok to block access to Alice' server IF it's known that it's Alice's server and not some random site. Mallory sometimes also thinks it's ok to block if protocol is unknown.

This problem solved by XRay in all of it's versions. It could be possible (if overkill) to use mostly same methods to authenticate correct user and provide eir access.