Have you guys ever wondered how PIX or ASA firewall TCP 3 way handshake works? Well, its absolutely similiar to how the normal TCP/IP handshake works. Just a little different in terms of the syntax. For instance SYN flag in PIX is known as saA. For torubleshooting purposes, you would however need to know these flags in PIX/ASA. I had summarised a table of the flags and how it works.