Date: Sat, 9 Feb 2002 16:19:57 +0100 (CET) From: "Simon 'corecode' Schubert" <corecode@corecode.ath.cx> To: FreeBSD-gnats-submit@freebsd.org Subject: kern/34756: bad tcp chksum on certain ips Message-ID: <200202091519.g19FJvS00513@elevation.zuhause.stoert.net>
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>Number: 34756 >Category: kern >Synopsis: bad tcp chksum on certain ips >Confidential: no >Severity: critical >Priority: high >Responsible: freebsd-bugs >State: open >Quarter: >Keywords: >Date-Required: >Class: sw-bug >Submitter-Id: current-users >Arrival-Date: Sat Feb 09 07:30:00 PST 2002 >Closed-Date: >Last-Modified: >Originator: Simon 'corecode' Schubert >Release: FreeBSD 4.5-STABLE i386 >Organization: >Environment: System: FreeBSD elevation.zuhause.stoert.net 4.5-STABLE FreeBSD 4.5-STABLE #2: Sat Feb 9 14:06:54 CET 2002 corecode@elevation.zuhause.stoert.net:/usr/obj/i386/k7/usr/src/sys/ELEVATION i386 cvsupped every day 02:00 CET. this world+kernel compiled right now. >Description: Trying to connect to www.farnell.com results timeouts. tcpdump reveils: Script started on Sat Feb 9 16:07:26 2002 # tcpdump -nelpvvvxXi ed0 host www.farnell.com & telnet www.farnell.com 80 Trying 194.152.77.229... tcpdump: listening on ed0 16:07:31.710610 0:60:52:0:23:3a 0:60:52:0:d5:31 0800 74: 192.168.66.46.1044 > 194.152.77.229.80: S [bad tcp cksum fffe!] 595220480:595220480(0) win 65535 <mss 1460,nop,wscale 1,nop,nop,timestamp 76276 0> (DF) [tos 0x10] (ttl 64, id 3108, len 60) 0x0000 4510 003c 0c24 4000 4006 1b34 c0a8 422e E..<.$@.@..4..B. 0x0010 c298 4de5 0414 0050 237a 5800 0000 0000 ..M....P#zX..... 0x0020 a002 ffff 8edf 0000 0204 05b4 0103 0301 ................ 0x0030 0101 080a 0001 29f4 0000 0000 ......)..... 16:07:34.710878 0:60:52:0:23:3a 0:60:52:0:d5:31 0800 74: 192.168.66.46.1044 > 194.152.77.229.80: S [bad tcp cksum fffe!] 595220480:595220480(0) win 65535 <mss 1460,nop,wscale 1,nop,nop,timestamp 76576 0> (DF) [tos 0x10] (ttl 64, id 3118, len 60) 0x0000 4510 003c 0c2e 4000 4006 1b2a c0a8 422e E..<..@.@..*..B. 0x0010 c298 4de5 0414 0050 237a 5800 0000 0000 ..M....P#zX..... 0x0020 a002 ffff 8db3 0000 0204 05b4 0103 0301 ................ 0x0030 0101 080a 0001 2b20 0000 0000 ......+..... 16:07:37.711112 0:60:52:0:23:3a 0:60:52:0:d5:31 0800 58: 192.168.66.46.1044 > 194.152.77.229.80: S [bad tcp cksum fffe!] 595220480:595220480(0) win 65535 <mss 1460> (DF) [tos 0x10] (ttl 64, id 3127, len 44) 0x0000 4510 002c 0c37 4000 4006 1b31 c0a8 422e E..,.7@.@..1..B. 0x0010 c298 4de5 0414 0050 237a 5800 0000 0000 ..M....P#zX..... 0x0020 6002 ffff 05f4 0000 0204 05b4 `........... 16:07:40.711373 0:60:52:0:23:3a 0:60:52:0:d5:31 0800 58: 192.168.66.46.1044 > 194.152.77.229.80: S [bad tcp cksum fffe!] 595220480:595220480(0) win 65535 <mss 1460> (DF) [tos 0x10] (ttl 64, id 3137, len 44) 0x0000 4510 002c 0c41 4000 4006 1b27 c0a8 422e E..,.A@.@..'..B. 0x0010 c298 4de5 0414 0050 237a 5800 0000 0000 ..M....P#zX..... 0x0020 6002 ffff 05f4 0000 0204 05b4 `........... 16:07:43.711623 0:60:52:0:23:3a 0:60:52:0:d5:31 0800 58: 192.168.66.46.1044 > 194.152.77.229.80: S [bad tcp cksum fffe!] 595220480:595220480(0) win 65535 <mss 1460> (DF) [tos 0x10] (ttl 64, id 3152, len 44) 0x0000 4510 002c 0c50 4000 4006 1b18 c0a8 422e E..,.P@.@.....B. 0x0010 c298 4de5 0414 0050 237a 5800 0000 0000 ..M....P#zX..... 0x0020 6002 ffff 05f4 0000 0204 05b4 `........... 16:07:49.712113 0:60:52:0:23:3a 0:60:52:0:d5:31 0800 58: 192.168.66.46.1044 > 194.152.77.229.80: S [bad tcp cksum fffe!] 595220480:595220480(0) win 65535 <mss 1460> (DF) [tos 0x10] (ttl 64, id 3183, len 44) 0x0000 4510 002c 0c6f 4000 4006 1af9 c0a8 422e E..,.o@.@.....B. 0x0010 c298 4de5 0414 0050 237a 5800 0000 0000 ..M....P#zX..... 0x0020 6002 ffff 05f4 0000 0204 05b4 `........... ^C# ^D Script done on Sat Feb 9 16:08:10 2002 this happened in my previous world+kernel (from mid-january), too. i can't reproduce this problem on another fbsd (4.4-STABLE) machine. a quick check showed, that not only this ip address is affected: it *appears* that 194.152.77.209 still works (tcp chksum ok), .210 to .255 not. somehow every ip address that got its last byte above 209 produces a chsum error. very strange. >How-To-Repeat: try to establish a tcp connection to a host where the last byte of its ip address is 210 or above. >Fix: if i knew. >Release-Note: >Audit-Trail: >Unformatted: To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-bugs" in the body of the message
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