we are using 3rd party ipsec in transport mode from client to server, but when i put ASA 5520 with dynamic NAT , client is not establishing ipsec communication with server even if everything is allowed. How can the client connect by NAT with ASA 5520 with the same 3rd party ipsec from client to server. tell me the reqd. confguration in ASA 5520.without NAT clent and server use UDP 500 in both, (also tcp 5999 at server end for diferent applcaton at server)