Using Nagios to monitor "service-less" hosts

[Andy Shellam (Mailing Lists)]

Hi Fermin,

>> Is that right? Why don't fully decouple host-monitoring from service monitoring?

No.  Nagios does use the check-host-alive command to determine if the 
host is up - and, yes, hosts and services are separate in that a host 
doesn't have to have any services, but a service must have a host.

I have 2 hosts which are actually 2 gateway routers, which do not have 
any corresponding services.  Nagios issues a warning saying they don't 
have any services associated on every startup, but it monitors them 
perfectly.  Even if they drop off the network for a few seconds, Nagios 
knows about it.  This is through the use of check_ping as the 
check-host-alive command - however, on one of my previous servers, the 
gateway router blocked ICMP, so I used check_ssh as the check-host-alive 
command which also worked perfectly.

It sounds as if you don't have active checks enabled for the hosts.  The 
error "Not enough data..." means an active or passive check hasn't been 
submitted for the host yet.

Take a look at http://looking-glass.andyshellam.eu - this is my Nagios 
installation; the hosts SC_Gateway and FH_Gateway are the routers that 
do not have any services, whereas you'll notice the other 3 servers do.

Andy.

Fermín Galán Márquez wrote:
> Hello,
>
> I would like to use Nagios just to monitor the aliveness (i.e., UP/DOWN
> status) of a set of hosts. However, looking to the documentation and the
> sample that comes with the just installed software, I've seen that in order
> to do so two pieces of configuration are needed: a host declarartion (in the
> hosts.cfg file) using 'check-host-alive' command and a service declaration
> (in the services.cfg) file, expecifing a "PING" service using 'check_ping'
> as monitoring command (*).
>
> (*) However, from miscommands.cfg, it seems that check-host-alive command
> implementation is actually based on check_ping.
>
> Just defining the host (without the corresponding "PING" service
> declaration) doesn't seems to work: the host remains in "PENDING" state
> forever (with status information "Not enough data to determine host status
> yet"). It seems that Nagios deduces a host is UP if the services running in
> it are UP (so "Host *assumed* to be up"), but doesn't perform explicit
> monitoring of the host "itself".
>
> Is that right? Why don't fully decouple host-monitoring from service
> monitoring?
>
> Declaring the "PING" service is not an actual problem to me, but I'd just
> like to clarify this is the Nagios "phylosophy" :)
>
> Thanks in advance!
>
> Best regards,
>
> --------------------
> Fermín Galán Márquez
> CTTC - Centre Tecnològic de Telecomunicacions de Catalunya
> Parc Mediterrani de la Tecnologia, Av. del Canal Olímpic s/n, 08860
> Castelldefels, Spain
> Room 1.02
> Tel : +34 93 645 29 12 
> Fax : +34 93 645 29 01
> Email address: fermin.galan at cttc.es 
>
>
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-------------------------------------------------------------------------
Using Tomcat but need to do more? Need to support web services, security?
Get stuff done quickly with pre-integrated technology to make your job easier
Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo
http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642
_______________________________________________
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::: Please include Nagios version, plugin version (-v) and OS when reporting any issue. 
::: Messages without supporting info will risk being sent to /dev/null