>>> My web server's response time for http requests skyrockets every >>> weekday between about 9am and 5pm. I've gone over my munin graphs and >>> the only one that really correlates well with the slowdown is "TCP >>> Queuing". It looks like I normally have about 400 packets per second >>> graphed as "direct copy from queue" in munin throughout the day, but 2 >>> to 3.5 times that many are periodically graphed during work hours. I >>> don't see the same pattern at all from the graph of all traffic on my >>> network interface which actually peaks over the weekend. TCP Queuing >>> doesn't rise above 400 packets per second all weekend. This is >>> consistent week after week. >>> >>> My two employees come into work during the hours in question, and they >>> certainly make frequent requests of the web server while at work, but >>> if their volume of requests were the cause of the problem then that >>> would be reflected in the graph of web server requests but it is not. >>> I do run a small MTU on the systems at work due to the config of the >>> modem/router we have there. >>> >>> Is this a recognizable problem to anyone? >> >> >> I'm in the midst of this. Are there certain attacks I should check for? > > > It looks like the TCP Queuing spike itself was due to imapproxy which > I've now disabled. I'll post more info as I gather it.
imapproxy was clearly affecting the TCP Queuing graph in munin but I still ended up with a massive TCP Queuing spike today and corresponding http response time issues long after I disabled imapproxy. Graph attached. I'm puzzled. - Grant
