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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 |
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>>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 |
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>>second |
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>>>>> graphed as "direct copy from queue" in munin throughout the day, |
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>>but 2 |
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>>>>> to 3.5 times that many are periodically graphed during work hours. |
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>>I |
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>>>>> don't see the same pattern at all from the graph of all traffic on |
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>>my |
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>>>>> network interface which actually peaks over the weekend. TCP |
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>>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 |
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>>they |
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>>>>> certainly make frequent requests of the web server while at work, |
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>>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 |
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>>not. |
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>>>>> I do run a small MTU on the systems at work due to the config of |
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>>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 |
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>>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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>> |
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>> |
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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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>> |
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>>- Grant |
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> |
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> Things to check for: |
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> Torrent or other distributed downloads. |
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> Download program with multiple download threads |
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|
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|
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There sure shouldn't be anything like that running either on the |
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server or in the office. Is there a good way to find out? Maybe |
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something that would clearly indicate it? |
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|
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|
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> Maybe another proxy running? Esp. as you saw this also with imapproxy. |
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|
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|
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nginx acts as a reverse proxy to apache2 but that's a pretty common |
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config. Nothing else that I know of. |
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|
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- Grant |
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