Re: easy way to scan for issues with path mtu discovery?

[Bill Owens <owens () nysernet org>]

On Tue, Jun 24, 2008 at 10:28:12AM -0400, Darden, Patrick S. wrote:
> Hi all,
>
> Does anyone know of an easy way to scan for issues with path mtu discovery along a hop path?  E.g. if you think 
> someone is ICMP black-holing along a route, or even on the endpoint host, could you use some obscure nmap flag to 
> find out for sure, and also to identify the offending hop/router/host?  What tool would you use to test for this, and 
> how would you do such a test?  Is there any probing tool that does checks like this automatically?
>
> Seems to me this happens often enough that someone has probably already figured it out, so I am trying not to 
> reinvent the wheel.  All I can think of would be to handcraft packets of steadily increasing sizes and look for 
> replies from each hop on the route (which would be laborious at best).  Google has not been kind to my researches so 
> far.

scamper is the best tool I've found:

http://www.wand.net.nz/scamper/

Bill.