Date: Fri, 18 Jul 2008 15:59:31 +0200 From: Bernd Walter <ticso@cicely7.cicely.de> To: freebsd-net@freebsd.org Cc: Bernd Walter <ticso@cicely7.cicely.de> Subject: TCP zombie connections with 7-RELEASE and STABLE from 15th june Message-ID: <20080718135931.GA48087@cicely7.cicely.de>
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14:45:58.109631 IP 213.83.6.106.3270 > 85.159.14.110.443: S 470580731:470580731(0) win 32768 <mss 1460,nop,wscale 0,nop,nop,timestamp 1097693791 0> 14:45:58.109753 IP 85.159.14.110.443 > 213.83.6.106.3270: S 1364510055:1364510055(0) ack 470580732 win 65535 <mss 1460,nop,wscale 3,nop,nop,timestamp 2811134076 1097693791> 14:45:58.114324 IP 213.83.6.106.3270 > 85.159.14.110.443: . ack 1 win 33304 <nop,nop,timestamp 1097693796 2811134076> 14:45:59.816810 IP 213.83.6.106.3270 > 85.159.14.110.443: F 1:1(0) ack 1 win 33304 <nop,nop,timestamp 1097695539 2811134076> 14:45:59.816900 IP 85.159.14.110.443 > 213.83.6.106.3270: . ack 2 win 8326 <nop,nop,timestamp 2811135743 1097695539> 14:45:59.818445 IP 85.159.14.110.443 > 213.83.6.106.3270: F 1:1(0) ack 2 win 8326 <nop,nop,timestamp 2811135744 1097695539> 14:45:59.822859 IP 213.83.6.106.3270 > 85.159.14.110.443: . ack 2 win 33303 <nop,nop,timestamp 1097695545 2811135744> 14:46:00.415401 IP 213.83.6.106.3270 > 85.159.14.110.443: . ack 1 win 0 14:46:00.420082 IP 213.83.6.106.3270 > 85.159.14.110.443: . ack 2 win 33303 <nop,nop,timestamp 1097696156 2811135744> 14:46:00.420139 IP 85.159.14.110.443 > 213.83.6.106.3270: . ack 1 win 65535 14:46:00.424772 IP 213.83.6.106.3270 > 85.159.14.110.443: . ack 2 win 33303 <nop,nop,timestamp 1097696162 2811135744> 14:46:00.424847 IP 85.159.14.110.443 > 213.83.6.106.3270: . ack 1 win 65535 14:46:00.429065 IP 213.83.6.106.3270 > 85.159.14.110.443: . ack 2 win 33303 <nop,nop,timestamp 1097696166 2811135744> 14:46:00.429089 IP 85.159.14.110.443 > 213.83.6.106.3270: . ack 1 win 65535 14:46:00.433247 IP 213.83.6.106.3270 > 85.159.14.110.443: . ack 2 win 33303 <nop,nop,timestamp 1097696170 2811135744> 14:46:00.433305 IP 85.159.14.110.443 > 213.83.6.106.3270: . ack 1 win 65535 14:46:00.437641 IP 213.83.6.106.3270 > 85.159.14.110.443: . ack 2 win 33303 <nop,nop,timestamp 1097696175 2811135744> 14:46:00.437700 IP 85.159.14.110.443 > 213.83.6.106.3270: . ack 1 win 65535 14:46:00.442408 IP 213.83.6.106.3270 > 85.159.14.110.443: . ack 2 win 33303 <nop,nop,timestamp 1097696180 2811135744> 14:46:00.442445 IP 85.159.14.110.443 > 213.83.6.106.3270: . ack 1 win 65535 14:46:00.447231 IP 213.83.6.106.3270 > 85.159.14.110.443: . ack 2 win 33303 <nop,nop,timestamp 1097696184 2811135744> 14:46:00.447291 IP 85.159.14.110.443 > 213.83.6.106.3270: . ack 1 win 65535 14:46:00.451525 IP 213.83.6.106.3270 > 85.159.14.110.443: . ack 2 win 33303 <nop,nop,timestamp 1097696189 2811135744> 14:46:00.451587 IP 85.159.14.110.443 > 213.83.6.106.3270: . ack 1 win 65535 14:46:00.455957 IP 213.83.6.106.3270 > 85.159.14.110.443: . ack 2 win 33303 <nop,nop,timestamp 1097696194 2811135744> 14:46:00.456024 IP 85.159.14.110.443 > 213.83.6.106.3270: . ack 1 win 65535 14:46:00.460666 IP 213.83.6.106.3270 > 85.159.14.110.443: . ack 2 win 33303 <nop,nop,timestamp 1097696198 2811135744> 14:46:00.460732 IP 85.159.14.110.443 > 213.83.6.106.3270: . ack 1 win 65535 14:46:00.465092 IP 213.83.6.106.3270 > 85.159.14.110.443: . ack 2 win 33303 <nop,nop,timestamp 1097696203 2811135744> 14:46:00.465150 IP 85.159.14.110.443 > 213.83.6.106.3270: . ack 1 win 65535 [...] 14:46:31.182624 IP 85.159.14.110.443 > 213.83.6.106.3270: . ack 1 win 65535 14:46:31.182978 IP 213.83.6.106.3270 > 85.159.14.110.443: . ack 2 win 33303 <nop,nop,timestamp 1097727660 2811135744> 14:46:31.183006 IP 85.159.14.110.443 > 213.83.6.106.3270: . ack 1 win 65535 14:46:31.183146 IP 85.159.14.110.443 > 213.83.6.106.3270: F 1:1(0) ack 1 win 65535 14:46:31.183173 IP 85.159.14.110.443 > 213.83.6.106.3270: F 1:1(0) ack 1 win 65535 14:46:31.184038 IP 213.83.6.106.3270 > 85.159.14.110.443: . ack 2 win 33303 <nop,nop,timestamp 1097727661 2811135744> 14:46:31.184124 IP 213.83.6.106.3270 > 85.159.14.110.443: . ack 2 win 33303 <nop,nop,timestamp 1097727661 2811135744> 14:46:31.184157 IP 213.83.6.106.3270 > 85.159.14.110.443: . ack 2 win 33303 <nop,nop,timestamp 1097727661 2811135744> 14:46:31.184740 IP 213.83.6.106.3270 > 85.159.14.110.443: . ack 2 win 33303 <nop,nop,timestamp 1097727662 2811135744> 14:46:31.185174 IP 213.83.6.106.3270 > 85.159.14.110.443: . ack 2 win 33303 <nop,nop,timestamp 1097727662 2811135744> 14:46:31.186762 IP 213.83.6.106.3270 > 85.159.14.110.443: . ack 2 win 33303 <nop,nop,timestamp 1097727664 2811135744> 14:46:31.187366 IP 213.83.6.106.3270 > 85.159.14.110.443: . ack 2 win 33303 <nop,nop,timestamp 1097727664 2811135744> 14:46:31.187380 IP 213.83.6.106.3270 > 85.159.14.110.443: . ack 2 win 33303 <nop,nop,timestamp 1097727664 2811135744> 14:46:31.187573 IP 213.83.6.106.3270 > 85.159.14.110.443: . ack 2 win 33303 <nop,nop,timestamp 1097727665 2811135744> 443 is a self written server, but it also happens with port 80 and sslproxy. The client is a telnet, which disconnects directly after connecting, so the disconnect is initiated from the client, which seems to be important for this problem to trigger. You can see that the FIN handshake completes and netstat on the client box shows the connection in TIME_WAIT. The server however has the connection still in ESTABLISHED state. What happens in the application code looks quite silly. I do a typical accept loop and then I process the data in a new thread. After my thread terminates and closes it's filedescriptor the select loop accepts the old connection again. This doesn't happen in every case but almost always. Finally after 30 seconds without data to read my newly created thread closes the zombie connection again. The question is why accept returns me a filedescriptor for a connection which was already returned and should have been closed? -- B.Walter <bernd@bwct.de> http://www.bwct.de Modbus/TCP Ethernet I/O Baugruppen, ARM basierte FreeBSD Rechner uvm.
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