jha miku wrote:
In case of active open, the SYN segments always have timestamp enabled, since the RFC flg is set. But, Currently, I am seeing some SYN segments without timestamp option.
FreeBSD (and OS X, and other things using a BSD network stack) will generate initial TCP SYN packets containing the "MNWNNT" TCP options, at least by default in the absense of other information or settings.
The only condition that I am aware of when timestamp is disabled, is on sending the 3rd SYN in retransmit code when the timestamp gets disabled. looking at the tcpdump, it is unclear why the SYNs are sent during active open without timestamp option.
The TCP stack seems to remember some information about which TCP options a remote host is willing to accept. If the remote system didn't accept a timestamp the first time (perhaps it's talking to an old windows box which does "MNNS"), there is no point in sending that option out the next time you open a new connection to the same system.
-- -Chuck _______________________________________________ freebsd-net@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-net To unsubscribe, send any mail to "[EMAIL PROTECTED]"
