Access Problems with 7.0

[Erik Stian Tefre]

Doug Hardie wrote:
>> 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?

sysctl net.inet.tcp.rfc1323=0

This may disable more than you want, but maybe it's worth a try.

http://www.ietf.org/rfc/rfc1323.txt

--
Erik