When does the ProxySG establish an Schannel connection?

The ProxySG establishes an Schannel connection specifically when the client sends an NTLM type 3 message to the ProxySG. The NTLM type 3 message is part of the NTLM authentication process, indicating that the client has successfully authenticated itself and is ready to establish a secure connection with the server. This message includes the necessary credentials and confirms that the client is authenticated, allowing the ProxySG to proceed with creating the secure channel for subsequent communications.

In an NTLM authentication sequence, the type 3 message is critical as it signals the last step in the authentication process. Once this message is received by the ProxySG, it can validate the user's credentials and set up a secure Schannel connection, which is a protocol for securing communications through SSL/TLS.

Establishing an Schannel connection at this point is crucial for maintaining the confidentiality and integrity of the data transmitted between the client and the server, as it ensures that all subsequent data transfers are secured against eavesdropping and tampering.