3.8 Secure Tunnel Encapsulation of SSTP Protocol Server Details

From the server’s standpoint, the Secure Tunnel Proxy only exchanges SSTP messages with the server. The traffic between the proxy and the server is SSTP protocol traffic on a non-standard port for SSTP: 443/TCP. The server does not take part in the Secure Tunnel handshake. Secure Tunnel encapsulation occurs between the client and proxy server as part of the Secure Tunnel handshake. All messages that flow between the client and server are standard SSTP messages. See SSTP [MS-GRVSSTP] for server processing rules. All SSTP server processing rules apply except for those listed in sections 3.8.2 and 3.2.3.