/* TCP connection tracking based on 'Real Stateful TCP Packet Filtering
in IP Filter' by Guido van Rooij.
- http://www.nluug.nl/events/sane2000/papers.html
- http://www.iae.nl/users/guido/papers/tcp_filtering.ps.gz
+ http://www.sane.nl/events/sane2000/papers.html
+ http://www.darkart.com/mirrors/www.obfuscation.org/ipf/
The boundaries and the conditions are changed according to RFC793:
the packet must intersect the window (i.e. segments may be