This article http://www.ciscopress.com/articles/article.asp?p=345618&seqNum=3 describes TCP intercept mode:
One limitation of intercept mode is that any TCP options that are negotiated between the external user and the router (which normally are to the end-server device), such as RFC1323 window scaling, are not passed from the router to the internal TCP server. This is because the router does not know these options until the first three-way handshake completes with the external user and the router begins the second three-way handshake with the internal TCP server. Typically, this is not a problem because TCP allows for the dynamic negotiation of these parameters during the normal operation of the session.
What is dynamic negotiation TCP options? How can i use it? I have some TCP options that i want to work in tcp intercept mode and i don't want to use VPN softwares.