check_command in Nagios 1.2

[Sergey Semenyuk]

This is what is confusing in the FAQ:
Once !!!Nagios checks the status of the host!!! (or of at least one of
the services associated with the host), the host's state and status
information will be changed.

It status status of the host OR service ...

I've seen this as well

Whenever a service check results in a non-OK status level, Nagios will
attempt to check and see if the host that the service is running on is
"alive".

but couldn't understand WHY nagios would make an assumption without
checking the host status (relevant to the hosts without services)given
that in some situation the host status is an important criteria too.

Thanks a lot for help!


Sergey Semenyuk
LAN Administrator
Strategic Vista International Inc.
300 Alden Road,
Markham, ON, L3R 4C1
Phone: (905) 946-8589 x 180
Fax: (905) 947-0138 


-----Original Message-----
From: Marc Powell [mailto:marc at ena.com] 
Sent: Monday, December 06, 2004 10:55 AM
To: Sergey Semenyuk
Cc: nagios-users at lists.sourceforge.net
Subject: RE: [Nagios-users] check_command in Nagios 1.2 

Yes, if your host provides no other services that are interesting to you
(i.e. a router or switch) you'll want to add a ping service check for
it.

Some relevant reading --

http://nagios.sourceforge.net/docs/1_0/networkreachability.html 
http://www.nagios.org/faqs/viewfaq.php?faq_id=85&expand=false&showdesc=t
rue 
http://www.nagios.org/faqs/viewfaq.php?faq_id=86

--
Marc 

> -----Original Message-----
> From: Sergey Semenyuk [mailto:sergey at strategicvista.com]
> Sent: Monday, December 06, 2004 9:35 AM
> To: Marc Powell
> Cc: nagios-users at lists.sourceforge.net
> Subject: RE: [Nagios-users] check_command in Nagios 1.2
> 
> Thanks for advice.
> I just have noticed going through the sources that check_host is
> actually called from verify_host_"path" (whatever) when service status
> changes. And everything you said sounds perfectly understandable. So,
> you to check if the host is alive I need to have some kind of ping
> service, and both service and host status will change (just confirming
> my findings), because that "Assuming ..." was rather confusing.
> 
> Thanks for clearing things out for me.
> 
> Sergey Semenyuk
> LAN Administrator
> Strategic Vista International Inc.
> 300 Alden Road,
> Markham, ON, L3R 4C1
> Phone: (905) 946-8589 x 180
> Fax: (905) 947-0138
> 
> 
> -----Original Message-----
> From: Marc Powell [mailto:marc at ena.com]
> Sent: Monday, December 06, 2004 10:28 AM
> To: Sergey Semenyuk
> Cc: nagios-users at lists.sourceforge.net
> Subject: RE: [Nagios-users] check_command in Nagios 1.2
> 
> Do you have any service definitions for this host? The host will never
> be checked and will remain in a PENDING state if you do not have any
> services defined (that actually get checked themselves). Additionally,
> the host won't actually be checked and will only be assumed to be OK
> until one or more services on the host fails. It sounds to me like you
> don't have any services being checked on the host at this point.
> 
> Additionally, a host check of 20 probably isn't a good idea. If the
host
> _were_ to be checked, nagios will stop all processing except for this
> host check until all 20 attempts have completed. No additional service
> checks, updates, event handlers, etc will run until this completes.
You
> should only perform the minimal number of pings/attempts to determine
> the state of the host. In many cases a single ping is sufficient or
just
> a handful if you have a lossy network.
> 
> --
> Marc
> 
> > -----Original Message-----
> > From: nagios-users-admin at lists.sourceforge.net [mailto:nagios-users-
> > admin at lists.sourceforge.net] On Behalf Of Sergey Semenyuk
> > Sent: Monday, December 06, 2004 9:15 AM
> > To: 'Stephan Janosch'
> > Cc: nagios-users at lists.sourceforge.net
> > Subject: RE: [Nagios-users] check_command in Nagios 1.2
> >
> > Absolutely:
> >
> > Host (they are all the same)
> > define host{
> >         use                     generic-host            ; Name of
host
> > template to use
> >
> >         host_name               sfw
> >         alias                   Main Router (Linux)
> >         address                 192.168.20.2
> >         check_command           check-host-alive (I tried
> > check-host-echo from the demo site as well)
> >         parents                 mainswitch
> >         checks_enabled          1
> >         max_check_attempts      20
> >         notification_period     24x7
> >         notification_options    d,u,r
> >         stalking_options        o,d,u
> >         }
> >
> >
> > commands:
> >
> > define command{
> >         command_name    check-host-alive
> >         command_line    $USER1$/check_ping -H $HOSTADDRESS$ -w
> > 3000.0,80% -c 5000.0,100% -p 1
> >         }
> >
> >
> > define command{
> > command_name check-host-echo
> > command_line $USER1$/check_tcp -H $HOSTADDRESS$ -p 7
> > }
> >
> > No firewalls on internal network at all.
> > Started looking sources, and debug0, no check_host calls at all.
> >
> > Thanks in advance.
> >
> >
> > -----Original Message-----
> > From: Stephan Janosch [mailto:Stephan.Janosch at interface-business.de]
> > Sent: Monday, December 06, 2004 10:03 AM
> > To: Sergey Semenyuk
> > Cc: nagios-users at lists.sourceforge.net
> > Subject: Re: [Nagios-users] check_command in Nagios 1.2
> >
> > Sergey Semenyuk wrote:
> > > Hi,
> > >
> > > I am having issues with check_command in hosts specifications. I
> have
> > > actually used sample configuration files and checked the configs
on
> > the
> > > demo site, but still no luck. I tried getting some help from the
IRC
> > > channel but RTFM was the answer. I figure that even if I read the
> > manual
> > > for ten times I will barely become smarter. All other plugins and
> > > commands specifications work fine, but hosts check_command doesn't
> > seem
> > > to work for me at all and I get PENDING status with not enough
> > > information. I tried various debug levels but don't seem to see
from
> > > them that Nagios actually tries running that check_command. Any
> other
> > > place except for the sources I have to look?
> > >
> > > Thanks in advance.
> > >
> > > Sergey
> >
> > Can you post at least one host definition here? And please post the
> > definition of the host check command too!
> 





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