Re: Preventing SSH timeouts . Some clarification needed

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Hi Guys ,

Finally got the clarification . We are not behind NAT . I checked
myself by injecting some packets and sniffing the packets on the dest
host as Michael suggested .
I tried the experiment both ways and the no changes in ip address can
be seen . I cross verified with our network-admin that those hosts are
not behind NAT .
So , most likely case for these connection drop-out are



2010/6/9 Michal Nazarewicz <mina86@xxxxxxx>:
>> 2010/6/8 Michal Nazarewicz <mina86@xxxxxxx>:
>>> If “ifconfig” on one host gives you different IP addresses then the
>>> other host see as incoming IP then you are behind NAT.
>
> query <query.cdac@xxxxxxxxx> writes:
>> Sorry , I failed to understand the above statement . But I have
>> something in mind , I will try it tomorrow .
>> From the source machine , I send a packet to remote host on a
>> different network   . Now If I  capture packet on the remote host and
>> it comes out to be different ip address than the source host , then
>> probably I am behind NAT.  These hosts are having private ip address.
>
> Yes, that's what I've written. ;)
>
> You run “ifconfig” an one machine at it will show you what's it's IP
> address (there may be several interfaces).  Then you connect from this
> machine to the other machine and check the source address on the other
> machine.  Repeat for the other direction even thou, if you actually can
> connect from one machine to the other then it is likely that the one you
> are connecting to is not behind NAT.
>
>> These hosts are not providing any Internet service and mainly
>> responsible for processing around Gigabits of data . The processing
>> continues for around 24 hours , During the processing , it utilizes
>> around 100% CPU for around 4 hours and the connection drop happened
>> during that time . Not sure what processig goes on during the time
>> which takes all the CPU . The user we are talking here is the user
>> under whom these processes runs .
>
> If the processing takes so much time and is so CPU consuming I'd try
> running it with nice, ie.: “nice -n 20 process-data” rather then plain
> “process-data” command.
>
> If the dropping in fact happens only while high CPU usage than maybe in
> fact it is a culprit.  By running the processing via nice it gets lower
> priority (so in effect everything else gets higher priority in
> comparison).  This could help SSH get its desired CPU interval in time.

Thanks for this suggestion . But probably , we will not be able to do
that  . Our application itself is doing ssh to the other host and
during high load
the ssh connection drops and our application fails.

>
> --
> Best regards,                                         _     _
>  .o. | Liege of Serenly Enlightened Majesty of      o' \,=./ `o
>  ..o | Computer Science,  Michal "mina86" Nazarewicz   (o o)
>  ooo +--<mina86-tlen.pl>--<jid:mina86-jabber.org>--ooO--(_)--Ooo--
>

Thanks
Zaman
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