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Re: weirdness with TCP timeouts?

From The Natural Philosopher <tnp@invalid.invalid>
Newsgroups comp.os.linux.misc
Subject Re: weirdness with TCP timeouts?
Date 2014-09-08 17:54 +0100
Organization albasani.net
Message-ID <lukmvp$bhu$1@news.albasani.net> (permalink)
References <luk078$pfl$1@news.albasani.net> <le21eb-5e8.ln1@squidward.local.dionic.net>

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On 08/09/14 17:35, Tim Watts wrote:
> On 08/09/14 11:25, The Natural Philosopher wrote:
>
>> The second issue was that ssh sessions to my remote server were timing
>> out. They never used to, but I pulled the ssh keepalive down to a couple
>> of minutes and now the session stays up.
>
> As that is possibly a reproducible and simple problem, could you put the
> timeout up and run a tcpdump against it until it dies and see if
> anything happens at the end?
>

Mmm tcpdump is a thought.

as is netstat..

netstat -a | grep ESTABLISHED
tcp        0      0 192.168.0.6:37903       my.private.server:ssh 
ESTABLISHED
tcp        0      0 192.168.0.6:55445       four.schnuerpel.eu:nntp 
ESTABLISHED
tcp        0      0 192.168.0.6:667         tempest:nfs 
ESTABLISHED
tcp        0      0 192.168.0.6:55463       four.schnuerpel.eu:nntp 
ESTABLISHED
tcp6       0      0 ip6-localhost:41281     ip6-localhost:ipp 
ESTABLISHED
tcp6       0      0 ip6-localhost:ipp       ip6-localhost:41281 
ESTABLISHED

That shows that t'bird IS keeping nntp alive.

My guess is that the far end or the local end is timing out...

MM. a few other other  connections have popped up there in later scans.

I wonder WTF is going on..


>> That is in some way sockets are being closed inside the kernel in ways
>> they shouldn't be. And applications are not being notified that they
>> have closed.
>>
>> IN short my fevered imagination is considering the possibility that TCP
>> timeouts in the kernel have changed in  unexpected ways, so that
>> connections that used to exist, have been silently dropped.
>
> Not aware of anyhing which means bugger all here -
>
> Just one observation - have you changed the device that provides your
> NAT (if any) to the internet recently? NAT clearing sessions could cause
> these symptoms

No, that's been the same throughout.



-- 
Everything you read in newspapers is absolutely true, except for the 
rare story of which you happen to have first-hand knowledge. – Erwin Knoll

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Thread

weirdness with TCP timeouts? The Natural Philosopher <tnp@invalid.invalid> - 2014-09-08 11:25 +0100
  Re: weirdness with TCP timeouts? Tim Watts <tw_usenet@dionic.net> - 2014-09-08 17:35 +0100
    Re: weirdness with TCP timeouts? The Natural Philosopher <tnp@invalid.invalid> - 2014-09-08 17:54 +0100
      Re: weirdness with TCP timeouts? The Natural Philosopher <tnp@invalid.invalid> - 2014-09-08 18:06 +0100
  Re: weirdness with TCP timeouts? Johnny <johnny@invalid.net> - 2014-09-08 13:25 -0500
    Re: weirdness with TCP timeouts? The Natural Philosopher <tnp@invalid.invalid> - 2014-09-08 19:27 +0100
  Re: weirdness with TCP timeouts? Chick Tower <c.tower@deadspam.com> - 2014-09-19 02:33 +0000
    Re: weirdness with TCP timeouts? The Natural Philosopher <tnp@invalid.invalid> - 2014-09-19 06:30 +0100

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