Date: Thu, 18 Jul 2002 17:46:43 -0500 From: Dan Nelson <dnelson@allantgroup.com> To: Benjamin Franks <benjamin@dzhan.com> Cc: freebsd-questions@FreeBSD.ORG Subject: Re: tcp SYN retries? Message-ID: <20020718224643.GA74352@dan.emsphone.com> In-Reply-To: <20020718145818.M46100-100000@crimea.dzhan.com> References: <20020718145818.M46100-100000@crimea.dzhan.com>
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In the last episode (Jul 18), Benjamin Franks said: > When I attempt to make a sock_stream connection to an IP, and DON'T > receive an ACK or RST response, it seems that the system retries a finite > number of times by sending additional SYN packets. There also looks to be > a 3 or 6 second delay between SYN retries. After four or five, the > connection fails. The delays are stored in /sys/netinet/tcp_timer.c, tcp_syn_backoff[]. Those numbers are multiplied by 3 ( TCPTV_RTOBASE - the default retransmit timeout) to get the 3, 3, 3, 3, 3, 6, 12, 24 delays you are seeing. > Is there a way I can change the interval time for SYN retries, or > decrease the number of times it retries? I would imagine this would > be dependent on the particular tcp/ip stack implementation of my OS. > I'm using FreeBSD and would imaging some kernel sysctl variable would > control this... Any ideas? Or perhaps it's a socket option? You'll have to twiddle those numbers and rebuild the kernel. -- Dan Nelson dnelson@allantgroup.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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