Something with filters

[Jeroen Massar]

I was doing some traceroutes to determine some weird claim of a transit
(not shown in the below trace) being "tier1" while another transit
actually popped up in their network and then noticed this beauty:

 9  2001:5a0:a00::2e (2001:5a0:a00::2e)  79.018 ms  79.910 ms  79.960 ms
10  :: (::)  101.893 ms  102.004 ms  103.574 ms
11  rar3.chicago-il.us.xo.net (::ffff:65.106.1.155)  104.732 ms

Yeah baby, we can use the unspecified address in ICMP replies!

Why oh why is that packet even allowed to come back to me, let alone
travel all those hops...

Oh, yeah, something with uRPF and other such awesome standards.

Greets,
 Jeroen