CHECK_NRPE: Socket timeout after 10 seconds.

[J. Bakshi]

Mark Young wrote:
> On Sep 2, 2008, at 9:44 AM, J. Bakshi wrote:
>
>   
>> J. Bakshi wrote:
>>     
>>> Alex Dehaini wrote:
>>>
>>>       
>>>> Dude,
>>>>
>>>> I am assisting with nagios not your firewall. Read your firewall  
>>>> docs
>>>> very well. Remember to always read the documentation carefully  
>>>> before
>>>> requesting for assistance that are already in the docs.
>>>>
>>>>         
>>> The nrpe docs mentions abt the firewall rules which I have already  
>>> used,
>>> but no luck :-(
>>>
>>>       
>> Not firewall; I have solved the problem by incresing time with -t
>>     
>
>  From what you are describing I believe that this is a problem with  
> your xinetd nrpe configuration.  I run into this problem a lot.  By  
> default Xinet will only allow so many instances per second that if  
> exceeded xinet will refuse connects for certain amount of time.   
> Basically your remote server thinks that it is being DDoS.  Increasing  
> the time is only covering a symptom.
>   

Hi Mark,

Thanks for your hints and configuration.
I'm not using xinetd. I'm using nrpe daemon instead.
May be my firewall is responsible for the problem but I'm not sure
Even after increasing the time with  -t 20 the commands still report
socket time out :-(

Here is the rule set I have in my firewall. May be this create the problem

## SYN-FLOODING PROTECTION
# This rule maximises the rate of incoming connections. In order to do
this we divert tcp
# packets with the SYN bit set off to a user-defined chain. Up to
limit-burst connections
# can arrive in 1/limit seconds ..... in this case 4 connections in one
second. After this, one
# of the burst is regained every second and connections are allowed
again. The default limit
# is 3/hour. The default limit burst is 5.
#
iptables -N syn-flood
iptables -A INPUT -i $IFACE -p tcp --syn -j syn-flood
iptables -A syn-flood -m limit --limit 1/s --limit-burst 4 -j RETURN
iptables -A syn-flood -j DROP


with regards
 
> You can change this globally or per service by adding these lines in  
> ether /etc/xinetd.conf or /etc/xinetd.d/nrpe.  You can play with the  
> exact numbers you need.  I believe the default is 50 connections a  
> second.
>
> # CPS where 100 connection per second with a timepout of 10 seconds if  
> exceded.
>
> # Max number of instances running
>
> [myoung at vserve xinetd.d]# more nrpe
> # default: on
> # description: NRPE (Nagios Remote Plugin Executor)
> service nrpe
> {
>         	flags           = REUSE
>          socket_type     = stream
> 	port		= 5666
>         	wait            = no
>          user            = nagios
> 	group		= nagios
>         	server          = /usr/local/nagios/bin/nrpe
>          server_args     = -c /usr/local/nagios/etc/nrpe.cfg --inetd
>         	log_on_failure  += USERID
>          disable         = no
> 	only_from       = 127.0.0.1,IP.ADDRESS.OF.NAGIOS
> 	cps		= 100 10
> 	instances	= 300
> }
>
>
> Good luck!
>
> Mark Young
> ___
> Nagios Enterprises, LLC
> Web:    www.nagios.com
>
>
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>   


-- 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Joydeep Bakshi, Linux System Admin
Kolkatainfoservices Pvt Ltd,
23A Royd Street, Kolkata 700016, India
Work Phone 91 033 40014784
http://infoservices.in/
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


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