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