> >> If "RFC 2923 section 2.1" doesn't do it, there probably isn't much
> >> that will, short of an interactive explanation in person.
> > It sounds like we need an www.rfc-ignorant.org category for this sort
> > of misconfiguration.
> 
> Perhaps. :-)  But it's not restricted to Webservers.  I know of at
> least one person who's had trouble sending me large emails because the
> relevant outgoing mailhost has the won't-frag disease, and my logs show
> identical symptoms from many other hosts that have't been important
> enough for me to verify that the problem is won't-frag.

I wonder if it possible to locate the 'black hole' by sending large
ICMP echo packets with 'dont fragment' and a small 'hop count',
comparing the result to the usual 'traceroute' sequence.

    David