amd64/123603: tcp_do_segment and Received duplicate SYN
yes298 at gmail.com
Mon May 12 07:50:01 UTC 2008
>Synopsis: tcp_do_segment and Received duplicate SYN
>Arrival-Date: Mon May 12 07:50:01 UTC 2008
>Release: FB7.0 (x64)
FreeBSD mail.mydomain.com 7.0-RELEASE FreeBSD 7.0-RELEASE #0: Thu Mar 6 12:04:57 HKT 2008 root at mydomain.com:/usr/src/sys/amd64/compile/FB7NEW amd64
A FreeBSD 7.0 (x64) Lighttpd Web Server with most-updated ports and patchs.
when a client connect and view a static HTML file, At the first time (before web server idle time), it needs to wait a long time to establish a connection, OR when this server try to download file from Internet, there are lots of logs messages just like below:
May 12 11:57:54 mail kernel: TCP: [184.108.40.206]:41792 to [220.127.116.11]:80 tcpflags 0x2<SYN>; syncache_add: Received duplicate SYN,
resetting timer and retransmitting SYN|ACK
May 12 15:17:53 mail kernel: TCP: [18.104.22.168]:45979 to [22.214.171.124]:63372 tcpflags 0x10<ACK>; tcp_do_segment: FIN_WAIT_1: Received 1448 bytes of data after socket was closed, sending RST and removing tcpcb
May 12 15:17:53 mail kernel: TCP: [126.96.36.199]:21 to [188.8.131.52]:55007 tcpflags 0x18<PUSH,ACK>; tcp_do_segment: FIN_WAIT_2: Received 13 bytes of data after socket was closed, sending RST and removing tcpcb
any type of connection will generate above log messages.
no idea .
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