Date: Thu, 4 Feb 1999 14:51:10 +0200 (SAT) From: Graham Wheeler <gram@cdsec.com> To: hackers@FreeBSD.ORG Subject: TCP keepinit time and connection timeouts Message-ID: <199902041251.OAA27910@cdsec.com>
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Hi folks We have noticed that the connect() timeout when the target host does not respond is much shorter than the value specified by the TCP keepinit time. With TCP keepinit set to 25, connect() timesout after about 10 seconds, while with TCP keepinit set to 75, connect() times out after about 37 seconds. So it appears the keepinit time is being divided by some value in the range 2.0 - 2.5 to obtain the actual timeout. We were wondering whether (i) the divisor is constant, and the variation we are seeing is as a result of additional processing and (ii) why the divisor is not 1 (my guess is that the keepinit time is for the entire connection attempt, and a TCP SYN, being a `half-open', is being subjected to approximately half the timeout, but that is pure speculation on my part). Can anyone shed any light on this? TIA Graham -- Dr Graham Wheeler E-mail: gram@cdsec.com Citadel Data Security Phone: +27(21)423-6065/6/7 Firewalls/Virtual Private Networks Fax: +27(21)24-3656 Internet/Intranet Network Specialists Data Security Products WWW: http://www.cdsec.com/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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