Date: Mon, 31 Mar 2008 14:13:57 -0700 From: Doug Hardie <bc979@lafn.org> To: FreeBSD Stable <freebsd-stable@freebsd.org> Subject: Access Problems with 7.0 Message-ID: <C9F5484A-534B-4218-9993-F9C73999FF84@lafn.org>
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> 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?
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