MySQL Madness
Joe Renwick
joe at gonetforward.com
Fri Apr 29 03:40:24 UTC 2011
So I am seeing some interesting behavior of TCP during a MySQL connect over
the network. The following packets capture shows the packet flow:
asa1# sh capture debug-in
8 packets captured
1: 21:49:13.461554 8.25.42.100.32929 > 74.81.76.195.3306: S
4107544000:4107544000(0) win 65535 <mss 1380,nop,wscale 3,sackOK,timestamp
2065216038 0>
2: 21:49:13.462073 74.81.76.195.3306 > 8.25.42.100.32929: S
2601320299:2601320299(0) ack 4107544001 win 5792 <mss 1460,sackOK,timestamp
2581054349 2065216038,nop,wscale 7>
3: 21:49:13.462210 74.81.76.195.3306 > 8.25.42.100.32929: P
2601320300:2601320363(63) ack 4107544001 win 46 <nop,nop,timestamp
2581054349 2065216038>
4: 21:49:13.519061 8.25.42.100.32929 > 74.81.76.195.3306: . ack 2601320300
win 8208 <nop,nop,timestamp 2065216096 2581054349>
5: 21:49:14.135384 8.25.42.100.32929 > 74.81.76.195.3306: P
4107544001:4107544003(2) ack 2601320300 win 8208 <nop,nop,timestamp
2065216712 2581054349>
6: 21:49:14.135521 74.81.76.195.3306 > 8.25.42.100.32929: . ack 4107544003
win 46 <nop,nop,timestamp 2581055023 2065216712>
7: 21:49:16.461981 74.81.76.195.3306 > 8.25.42.100.32929: P
2601320300:2601320363(63) ack 4107544003 win 46 <nop,nop,timestamp
2581057349 2065216712>
8: 21:49:16.618147 8.25.42.100.32929 > 74.81.76.195.3306: . ack 2601320363
win 8208 <nop,nop,timestamp 2065219195 2581057349>
8 packets shown
Packet "1" is Syn from MySQL client to Server
Packet "2" is Syn/Ack from Server
Packet "3" is a TCP Push! ??? HERE IS WHERE I AM CONFUSED
Packet "4" is the Ack from the client completing the 3-way hand shake.
My firewall is dropping packet "3" as it is not happy there is a push going
on before it sees the completed handshake. Anybody run across this? Is the
a MySQL option for a faster connection?
Finally the firewall is a Cisco ASA and the "TCP Normalization" feature is
dropping the packet. Specifically is the "tcp-3whs-failed" rule that is
being offended. I cannot seem to figure out a way to turn this off?
Thanks for the help.
Cheers,
--
Joe Renwick
IP Network Consultant, CCIE #16465
GO NETFORWARD!
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