Date: Mon, 21 Mar 2005 19:52:09 +0100 From: Robert Gogolok <robertgogolok@web.de> To: Charles Swiger <cswiger@mac.com> Cc: freebsd-questions@freebsd.org Subject: Re: FIN_WAIT_2 Message-ID: <423F17D9.70802@web.de> In-Reply-To: <7c82a2d1780970b84810aefc59bdb295@mac.com> References: <423EFE41.6040805@web.de> <56b90b3668acea792519e1e70a7b837a@mac.com> <423F05F2.3010101@web.de> <7c82a2d1780970b84810aefc59bdb295@mac.com>
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Charles Swiger wrote: > FIN_WAIT_2 is a name describing the state of a TCP connection. It's > defined in a state diagram in RFC-793. But otherwise, your description > is pretty good: > [ ... ] > | CLOSE +---------+ > | ------- | ESTAB | > | snd FIN +---------+ > | CLOSE | | rcv FIN > V ------- | | ------- > +---------+ snd FIN / \ snd ACK +---------+ > | FIN |<----------------- ------------------>| CLOSE | > | WAIT-1 |------------------ | WAIT | > +---------+ rcv FIN \ +---------+ > | rcv ACK of FIN ------- | CLOSE | > | -------------- snd ACK | ------- | > V x V snd FIN V > +---------+ +---------+ +---------+ > |FINWAIT-2| | CLOSING | | LAST-ACK| > +---------+ +---------+ +---------+ > | rcv ACK of FIN | rcv ACK of FIN | > | rcv FIN -------------- | Timeout=2MSL -------------- | > | ------- x V ------------ x V > \ snd ACK +---------+delete TCB +---------+ > ------------------------>|TIME WAIT|------------------>| CLOSED | > +---------+ +---------+ > > TCP Connection State Diagram > Figure 6. I've looked at the "Closing a Connection" chapter from the RFC and tried to understand it. The state diagram above shows that from the FINWAIT-2 state there is only one possible way to reach TIME WAIT. So FreeBSD must be using another extension of the RFC-793, when it's sending ACK messages in the FINWAIT-2 state? Wow, I'm confused at this point, I have a linux box here which was the previous webserver, and I can't remember seeing ACK's hitting the firewall logs as it is now with the FreeBSD webserver. Greetings, Robert!
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