Hi all A specific application can't connect its designated server through ISA. It connects the server with telnet through port 23 then tries to do authentication connection, but finally can't. It seems that it uses PPP in being authenticated because I can see PPP adaptor information from IPCONFIG result. There's nothing particular in ISA setting. I applied an enterprise policy and allowed all in both "Site and Content Rule" and "Protocol Rules" Any help on this will be very appreciated. Thanks all.