Paul Watson was inspired by last year’s Black Hat 2003 Las Vegas talk “BGP Vulnerability Testing” by Matthew Franz & Sean Convery. He found that Matt and Sean’s estimates for the time needed to guess the right TCP sequence number to reset a connection were overstated. This means a reset with a sequence number within the window would be accepted by the target. A well-written advisory by the UK’s NISCC states “an established connection will abort by sending a RST if it receives a duplicate SYN packet with initial sequence number in the TCP window””]
Source: https://taosecurity.blogspot.com/2004/04/comments-on-tcp-reset-worries-i.html