On September 20, 2016 2:38:03 AM GMT+02:00, Grant <emailgr...@gmail.com> wrote:
>>>> 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

Things to check for:
Torrent or other distributed downloads.
Download program with multiple download threads

Maybe another proxy running? Esp. as you saw this also with imapproxy.

--
Joost
-- 
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