Date: Thu, 3 Apr 2008 18:44:00 +0000 (UTC) From: "Bjoern A. Zeeb" <bzeeb-lists@lists.zabbadoz.net> To: Doug Hardie <bc979@lafn.org> Cc: FreeBSD Stable <freebsd-stable@freebsd.org> Subject: Re: Access Problems with 7.0 Message-ID: <20080403183952.G66744@maildrop.int.zabbadoz.net> In-Reply-To: <C9F5484A-534B-4218-9993-F9C73999FF84@lafn.org> References: <C9F5484A-534B-4218-9993-F9C73999FF84@lafn.org>
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On Mon, 31 Mar 2008, Doug Hardie wrote: Hi, >> I recently upgraded 3 of my 5 servers to 7.0. Two of them are on new >> hardware and one is on hardware that used to run 6.2. Since then, 2 of my >> thousands of users are unable to access the servers running 7.0. They can >> access the server running 6.2 just fine. What happens is the server >> receives the SYN packet from the client properly and then responds with the >> SYN packet. Nothing more is heard from the client. The server sends a few >> duplicates of the SYN and then drops the connection. >> >> At this point I am not able to verify that the client receives the SYN. >> Neither of them has a clue about tcpdump. The packets look fine on this >> end (included later). Both are using Windows, including XP and Vista. I >> suspect they are receiving it and not accepting it for some reason. >> However, I don't really see anything that would cause that behavior in the >> packets. I can't reproduce the problem here. Every computer I can try >> works just fine. >> >> Here is one of the packet traces: >> >> 11:59:00.630414 00:00:0c:38:6f:e1 (oui Cisco) > 00:a0:cc:3e:87:9e (oui >> Unknown), ethertype IPv4 (0x0800), length 66: >> cpe-76-169-78-119.socal.res.rr.com.59025 > zool.lafn.org.8000: S >> 2779920420:2779920420(0) win 8192 <mss 1460,nop,wscale 2,nop,nop,sackOK> >> >> 11:59:00.630634 00:a0:cc:3e:87:9e (oui Unknown) > 00:00:0c:38:6f:e1 (oui >> Cisco), ethertype IPv4 (0x0800), length 66: zool.lafn.org.8000 > >> cpe-76-169-78-119.socal.res.rr.com.59025: S >> 2480373222:2480373222(0) ack 2779920421 win 65535 <mss 1460,nop,wscale >> 3,sackOK,eol> >> >> 11:59:03.613011 00:00:0c:38:6f:e1 (oui Cisco) > 00:a0:cc:3e:87:9e (oui >> Unknown), ethertype IPv4 (0x0800), length 66: >> cpe-76-169-78-119.socal.res.rr.com.59025 > zool.lafn.org.8000: S >> 2779920420:2779920420(0) win 8192 <mss 1460,nop,wscale 2,nop,nop,sackOK> >> >> 11:59:03.613194 00:a0:cc:3e:87:9e (oui Unknown) > 00:00:0c:38:6f:e1 (oui >> Cisco), ethertype IPv4 (0x0800), length 66: zool.lafn.org.8000 > >> cpe-76-169-78-119.socal.res.rr.com.59025: S 2480373222:2480373222(0) ack >> 2779920421 win 65535 <mss 1460,nop,wscale 3,sackOK,eol> >> > > Checking with the 6.2 server I see there are some differences in the TCP > options. 7.0 includes wscale 3 where 6.2 does not. Is there a way to > disable that feature using sysctl to see if thats the issue? You want to update to 7-STABLE which has the TCP fixes or you want to apply the following changes: 1.141.2.4 +10 -2 src/sys/netinet/tcp_output.c 1.157.2.2 +5 -2 src/sys/netinet/tcp_var.h In case you are not using MD5 that should be enough. Else see freebsd-net from the last 3 days for another patch. /bz -- Bjoern A. Zeeb bzeeb at Zabbadoz dot NeT Software is harder than hardware so better get it right the first time.
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