State Mismatch and tcp.closed
Martin Turgeon
freebsd at optiksecurite.com
Thu May 28 17:02:17 UTC 2009
Hi list!
I had a problem with state mismatch on my DB server that I solved by
lowering the tcp.closed timeout. I setted it to 2 instead of 90.
I now have what looks like the same problem on the front-end web server.
However, when I tried to apply the same fix, I got connection problem
with the back-end DB, but the state mismatch disappearred.
On the front-end web server, the state mismatch occurs on the external
interface, only on port 80.
I enabled misc debugging and got this in /var/log/messages on the
front-end web server:
May 28 05:02:19 francis kernel: pf: BAD state: TCP 127.0.0.25:80
206.125.166.65:80 98.207.239.10:54737 [lo=820536733 high=820603340
win=65535 modulator=0 wscale=0] [lo=2871317100 high=2871375106 win=8326
modulator=0 wscale=3] 7:4 R seq=820536733 (820536732) ack=2871317100
len=0 ackskew=0 pkts=43:69 dir=in,fwd
May 28 05:02:19 francis kernel: pf: State failure on: |
May 28 05:02:19 francis kernel: pf: BAD state: TCP 127.0.0.25:80
206.125.166.65:80 98.207.239.10:54733 [lo=374985971 high=375052578
win=65535 modulator=0 wscale=0] [lo=2999164748 high=2999229169 win=8326
modulator=0 wscale=3] 7:4 R seq=374985971 (374985970) ack=2999164748
len=0 ackskew=0 pkts=40:54 dir=in,fwd
May 28 05:02:19 francis kernel: pf: State failure on: |
May 28 05:03:06 francis kernel: pf: BAD state: TCP 127.0.0.20:80
206.125.166.80:80 123.116.84.41:59776 [lo=3407758259 high=3407823796
win=4096 modulator=0 wscale=2] [lo=374200006 high=374216390 win=8192
modulator=0 wscale=3] 4:2 A seq=3407758259 (3407758260) ack=2320196160
len=0 ackskew=-1945996154 pkts=1:1 dir=in,fwd
May 28 05:03:06 francis kernel: pf: State failure on: 3 |
May 28 05:03:06 francis kernel: pf: BAD state: TCP 127.0.0.20:80
206.125.166.80:80 123.116.84.41:59776 [lo=3407758259 high=3407823796
win=4096 modulator=0 wscale=2] [lo=374200006 high=374216390 win=8192
modulator=0 wscale=3] 4:2 RA seq=3407758259 (3407758260) ack=2320196160
len=0 ackskew=-1945996154 pkts=1:1 dir=in,fwd
This server has been up for 12 days and already got almost 600000 state
mismatch!
I tried to lower tcp.finwait, no result. I tried to set optimization to
aggressive, no result. I tried to disable port randomization via sysctl,
no result either.
I tcpdumped and there is only a few RST so I don't understand why
tcp.closed would solve my problem. If it's a problem with source port
reuse, tcp.finwait should be the timeout that would help, not
tcp.closed, right?
How can a lower tcp.closed on the front-end cause mysql connection
problem with the back-end? I tcpdumped while there is a connection
problem with the DB and there is nothing that seems wrong, no RST at
all! The front-end web server tries to connect to the DB, wait 3 sec and
if it fails to establish a connection, it then tries to connect to a
read-only backup DB, on another server, which never fails to connect.
The only thing I'm sure is that it's the tcp.closed that cause the DB
connection problem. As soon as I remove it, the state mismatch comes
back on the external interface but there's no DB connection problem anymore.
What am I missing?
Martin
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