check_multi advice to check "Internet available"

[Marc Haber]

Hi,

On Mon, May 24, 2010 at 04:58:21PM -0700, Gordon Messmer wrote:
> On 05/24/2010 02:51 PM, Marc Haber wrote:
> > On Mon, May 24, 2010 at 03:37:13PM -0400, Matt Simmons wrote:
> >> Have you considered adding your upstream router as a host, and making
> >> it the parent of your remote hosts?
> >
> > Yes, but that's a workaround which will misfire in the case where it's
> > the own ISP that's faulty at its uplik.
> 
> If that's something you're concerned about, your check_multi will also 
> "misfire" when the problem is at the uplink for the machines that you're 
> monitoring.
> 
> Monitoring a gateway and making it the parent is in no way a "workaround".
> 
> An ideal installation for monitoring WAN-connected hosts would monitor 
> your default gateway and make that the parent of all hosts.  You'd also 
> monitor the router at each remote site and make that the parent of all 
> hosts at that site.

I know all this. My first Nagios experiences date back to when it was
still called Netsaint. Of course, the default gateway, the CPE and the
COE of the "local" ISP are monitored. But that's all that can be
comfortably monitored since the Internet uses dynamic routing and the
paths are subject to change without further notice. Furthermore, a lot
of housing providers configure their backbone and access routers to
not respond to pings, so it's a challenge to monitor these sites.

http://blog.zugschlus.de/archives/770-Nagios,-Parent-Hosts,-and-traceroute-on-the-Internet.html
has my thoughts on that matter (thankfully written in English). Be
aware that this article is more than a year old, so things have
changed since then.

Greetings
Marc

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Marc Haber         | "I don't trust Computers. They | Mailadresse im Header
Mannheim, Germany  |  lose things."    Winona Ryder | Fon: *49 621 72739834
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