I am trying to use S4U2Proxy and S4U2Self introduced in Java 8. Unfortunately I was not successfull in finding those many examples. My requirement is the client would send its certificate. I should then delegate (using kerberos) his request, connect to KDC, get the TGT, get the service ticket to contact another server on user's behalf and then finally contact the actual service by providing the service ticket. If you have a working example for some dummy client and server, it would be great