Date: Fri, 21 Feb 2003 14:32:06 -0500 From: Steve Shorter <steve@nomad.lets.net> To: freebsd-net@freebsd.org Subject: TCP stuck in LAST_ACK in 4.5 and 4.6?? Message-ID: <20030221143206.A9343@nomad.lets.net>
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Howdy! I have an ftp server that became sporadically inaccessable over the network. I did some poking around and found that there were about 8k TCP connections that were in the state "LAST_ACK". The limit for maxsockets is about 8k for this machine so the reason that new connections were failing was because the boundary for sockets had been reached. I graph the number of open files and sockets using MRTG and saw that for the last few weeks the number of open sockets had been gradually rising due to connections "stuck" in LAST_ACK, a clearly unstable condition. This is a 4.5p24 machine. I also checked another ftp server that is 4.6.2 and it exhibits the same behavour though the limit on maxsockets is not reached yet. I checked a mail server running 4.5p24 and it too has about 4k connections "stuck" in LAST_ACK. I have verified their presence for at least 1 day. The archives indicate that this has been a problem but was fixed in 4.5. So I was wondering if this problem is still in post 4.5 systems and upgrading to 4.8 will fix it or whether there is further investigation needed to solve this issue. Or what can I do to determine the problem or help someone if it is a kernel problem. # netstat -an|grep LAST|tail tcp4 0 0 66.xx.xx.xx.20 128.175.154.185.2676 LAST_ACK tcp4 0 0 66.xx.xx.xx.20 67.35.48.182.2886 LAST_ACK tcp4 0 0 66.xx.xx.xx.20 128.175.154.185.1758 LAST_ACK tcp4 0 0 66.xx.xx.xx.20 128.175.154.185.1757 LAST_ACK tcp4 0 0 66.xx.xx.xx.20 128.175.154.185.1690 LAST_ACK tcp4 0 0 66.xx.xx.xx.20 128.175.154.185.1322 LAST_ACK tcp4 0 0 66.xx.xx.xx.20 128.175.154.185.1065 LAST_ACK tcp4 0 0 66.xx.xx.xx.20 209.37.184.2.37067 LAST_ACK tcp4 0 0 66.xx.xx.xx.20 209.37.184.2.30984 LAST_ACK tcp4 0 0 66.xx.xx.xx.20 209.37.184.2.30865 LAST_ACK thanx - steve To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message
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