ipv6: difference between tracepath6 and scamper output

IPv6 Security

> I took a look at the tracepath information you sent for these nodes,
> which showed a bunch of unresponsive nodes but no information that
> might be useful for assigning blame.┬á It’d be cool to see these paths
> with scamper’s pmtud traceroute, which tries to find out the MTU for
> the hops that aren’t sending a PTB.
>
> with that list of IP addresses:
> scamper -c “trace -P udp-paris -M” -f <file>

though I used:

(for i in `cat f`; do echo “==================== $i”; tracepath6 -n $i; scamper -I “trace -P udp-paris -M $i”; done) >>f.out

This to show the difference between tracepath6 and scamper output, there are some to be seen, some quite scary (eg the 1455 change).
Could be that one just gets through the ICMP ratelimits in one run and not the other.

Those nodes are just blackholes it seems. Only the operators of that network will know what is going on.

I am always surprised to see networks filtering out packets, and especially wonder what they are trying to achieve with such a filter.

> http://www.caida.org/tools/measurement/scamper/
> http://www.caida.org/~mjl/pubs/debugging-pmtud.imc2005.pdf
>
> Happy to help anyway I can (I wrote scamper)

I am quite aware. Great tool, but not very verbose unfortunately. Hence, typically it just does/outputs nothing.

Greets,
Jeroen