Nagios reports its own host as DOWN

[Valeri Galtsev]

On Thu, September 22, 2016 5:37 pm, Per olof Ljungmark wrote:
> Hi,
>
> On 2016-09-21 10:03, Alnis Morics wrote:
>> Hi,
>>
>> I installed nagios4-4.1.1_5,1 on a FreeBSD 10.3 jail. (It's my first
>> time with Nagios)
>>
>> I managed the core to show up as working, and the system now lists its
>> first host (the one it is installed on) -- as DOWN.
>>
>> Small wander, because the way it checks this is by pinging "localhost"
>> (/sbin/ping -n -c 5 127.0.0.1 ), although ping is disabled in my jail
>> (as per default), and its localhost address is changed to 127.0.0.3.
>
> Well, if ping is disabled I suppose your systems behaves as intended?
> Not sure one wants to ping localhost in this case bacause if the host is
> down then Nagios would be as well? Or you read jail(8) to figure out how
> to allow ping.
>
> If you want to check real iron on the Nagios host it would probably be a
> lot easier not running it jailed although I'm sure it can be done.

I run nagios in jail. As you said ping localhost doesn't make much sense,
yet I didn't disable that. I check also a bunch of other services on
localhost, so I didn't threw away localhost part from my nagios
configuration.

As you said, one needs to read jail(8) and allow ping. One more thing, it
is helpful to do similar ping test from that same jail just from command
line. Similarly, before adding checking of some port on some host to
nagios, it is good to attempt from command line to telnet that host that
port. This way one can rule out firewalls etc, and will know it is nagios
part one needs to look into.

Valeri

>
>> How can I correct this checking? I found there is a script for checking
>> FreeBSD jails
>> (https://exchange.nagios.org/components/com_mtree/attachment.php?link_id=1859&cf_id=24)
>> but, again, I can't find any hint of how to use it or whether it can
>> help me at all. Will I be able to check services on jails of other
>> machines?
>
> Yes you will, both through the "real" host or nrpe on the jailed.
>
> There may be other things that blocks of course like firewalls etc.
>
> Cheers,
>
> //per
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++++++++++++++++++++++++++++++++++++++++
Valeri Galtsev
Sr System Administrator
Department of Astronomy and Astrophysics
Kavli Institute for Cosmological Physics
University of Chicago
Phone: 773-702-4247
++++++++++++++++++++++++++++++++++++++++