check_icmp v0.8

[Jamie Baddeley]

On Thu, 2004-12-30 at 00:51 +0100, Andreas Ericsson wrote:
> Jamie Baddeley wrote:
> > I've noticed that when check_icmp checks a host that results in ICMP
> > unreachables, the ICMP unreachable messages spill over* into other check
> > results (specifically status information) for other hosts...Which I am
> > fairly sure is not desirable.. I also notice from CLI that for the host
> > in question, for 5 pings, 5 ICMP unreachable messages are produced (over
> > and above the check result)
> > 
> 
> Do you mean the status string is shown for other hosts in the nagios 
> GUI, or that the status output from the check_icmp plugin is the same 
> whether you check one or multiple hosts?

Umm. Both.

For true down host, status info is 
ICMP Unreachable from 161.65.1.x for ICMP Echo sent to 161.65.7.x
in the gui.

For random other host foo in the gui, status info can be 
ICMP Unreachable from 161.65.1.x for ICMP Echo sent to foo
in the gui.

I couldn't count any more than 5 other random foo hosts showing the
symptoms at any one time....


> > testing with redirects seems to suggest the output is standard out, not
> > standard error.
> > 
> 
> This is by design. Nagios can't read stderr, so everything intended to 
> show up in the cgi's must be written to stdout.

Sure, what I was testing is whether you intentionally wanted the other
icmp unreachable info to appear, which it seems you do.

> 
> > Shouldn't check_icmp only result in one line of extra status info (i.e
> > icmp unreachable etc) *following* the actual result (i.e CRITICAL -
> > 161.65.7.x is down)?
> > 
> > Am I smoking crack or is this a bug?
> > 
> 
> It was originally a debug line which proved nifty to provide info when 
> improper routing was the cause of ICMP_UNREACH'es, so by general demand 
> I left it in there. An ICMP_UNREACH message indicates that one (or more) 
> routers along the way doesn't know what the next hop of the packet will 
> be, so all of the packets will fail (unless the router starts behaving 
> magically between two packets).

I agree that the info is useful, it's just that one line per check
rather than for each ping would be less troublesome. And appending the
extra info, rather than prepending it might fix things up??

> 
> Anyways. I'm about to undertake a rather massive rewrite of the 
> check_icmp plugin. It should fix most if not all of the issues users 
> have been having with it.
> 

Happy New Year! ;-)

> > 
> > noc:~# /usr/lib/nagios/plugins/check_icmp -H 161.65.7.x -w 10,10 -c
> > 20,20 -n 1 -r 1 2>/dev/null
> > 
> > ICMP Unreachable from 161.65.1.xxx for ICMP Echo sent to 161.65.7.x
> > ICMP Unreachable from 161.65.1.xxx for ICMP Echo sent to 161.65.7.x
> > CRITICAL - 161.65.7.x is down (lost 100%)|rta=;10;20;; pl=100%;10;20;;
> 
> That's a bit funny. It seems either the offending (offended?) router 
> sends duplicate ICMP's back, or check_icmp sends two packets when told 
> to send only 1.

Not really IMHO. It sends one, and then retries once. 1+1=2 :-)

> 
> Anyways. I'll add it to the testsuite to make sure it happens the right way.
> 
cool. thanks.




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