IPv6 ingress filter


As we are trying to tighten the security for IPv6 traffic in our network, I was looking for a reference IPv6 ingress filter.

I came up with Job Snijders suggestion (thank you Job) that can be conveniently found at whois -h whois.ripe.net fltr-martian-v6

After applying the filter I noticed some traffic from 6to4 addresses (2002::/16) to our native IPv6 prefixes (residential users in this case).

The traffic is a mix of both UDP and TCP but all on high port numbers on both destination and source.

It seems to me like some P2P traffic, but I really can’t tell.

This got me thinking, why should we filter these addresses at all ?

I know 6to4 is mostly dead, but is it inherently bad ?

And if so, why is the prefix (2002::/16) still being routed ?

I would love to hear some thoughts on this, and understand if others are actually filtering this at both data plane and control plane.


Amos Rosenboim

Hi Amos,

Just responded in another mailing list on this:

6to4 is still a valid protocol. IT SHOULD NOT be filtered. 6to4 uses the same protocol as other tunnels such as 6in4 (protocol 41).



Hello Jordi,

Thank you for your feedback on both lists.
It’s important to note that the filter suggestion is not about the protocol, but about the 2002::/16 prefix.