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Re: Router appears in tracert but can't ping?

On Tue, 17 Jun 2003 at 10:15:49, Russell Coker wrote:

> On Tue, 17 Jun 2003 16:05, Stefan Neufeind wrote:
> > both tracert and ping use ICMP. So did they just block some kind of
> > ICMP-message (ping) for this router? How could I solve this problem?
> Your message was not clear, but it seems that you can see the router on a 
> traceroute but can't ping it.
> Ping sends ICMP-ECHO packets and solicits a direct response.  traceroute
> sends 
> an ICMP-ECHO or a UDP packet destined for some machine beyond the router and
> the router sends back an ICMP time-exceeded if it's hop count has expired.  
> Configuring a router to not respond to any packets addressed to itself is not
> uncommon, but having it send ICMP messages about packets addressed to other 
> machines that it can't deliver is expected.
> For this reason it's not uncommon to see traceroute show 10.x.x.x or 
> 192.168.x.x addresses (which are obviously not pingable).
> I'm not sure how the Windows program tracert compares in functionality to 
> traceroute.

What I'm looking for is a possibility to see if this router (that denies ping-
packets) is still available? I have Nagios running and normally it monitors 
hosts via ping. So I need a replacement that would tell me if this router on 
the way to a server is reachable. I want to test the whole path to see where an 
error occured. Well, is it possible to "simulate" traceroute-like packets? What 
would you do to achive this?


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