SSTP Stealth VPN
Secure Socket Tunneling Protocol (SSTP) is a form of VPN tunnel that provides a mechanism to transport PPP or L2TP traffic through an SSL 3.0 channel. SSL provides transport-level security with key-negotiation, encryption and traffic integrity checking. The use of SSL over TCP port 443 allows SSTP to pass through virtually all firewalls and routers and cannot be blocked.
SSTP servers must be authenticated during the SSL phase. SSTP clients are authenticated during the SSL phase, and must be authenticated in the PPP phase. The use of PPP allows support for common authentication methods, such as EAP-TLS and MS-CHAP.
SSTP is available in Windows Vista Service Pack 1 and Windows 7 operating systems only. It is fully integrated with the RRAS architecture in these operating systems.
With regards to the SSTP Super Stealth VPN Technology, here is what happens when you initialize this type of connection:
1.) TCP connection is established from client to server (by default on port 443).
2.) SSL validates server certificate. If certificate is valid connection is established otherwise connection is torn down.
3.) The client sends SSTP control packets within the HTTPS session which establishes the SSTP state machine on both sides.
4.) PPP negotiation over SSTP. Client authenticates to the server and binds IP addresses to SSTP interface
5.) SSTP tunnel is now established and packet encapsulation can begin.
