The *first* packet from the answering side *must* be an M_NUL "OPT TLS".
If this is the case, the originating size responds with an M_NUL "OPT TLS".
After this, the answering system performs a server TLS handshake, and the
originating system performs a client TLS handshake.

OPT CRYPT is not used in this case (ie: not crypt over TLS)