Access Problems with 7.0

[Doug Hardie]

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>