IPv6 ingress filtering

JORDI PALET MARTINEZ jordi.palet at consulintel.es
Tue May 14 17:50:52 CEST 2019

Hi Marc,


I don’t agree. There are many users with tunnel brokers that use 6in4. If you filter 6to4 as a protocol, you’re also filtering all those users’ traffic.


Not everybody is lucky enough to have native IPv6 support from its ISP.






El 14/5/19 17:46, "Marc Blanchet" <ipv6-ops-bounces+jordi.palet=consulintel.es at lists.cluenet.de en nombre de marc.blanchet at viagenie.ca> escribió:


6to4 has been a good transition technology to help deploy IPv6 in the early days. However, it has intrinsically bad latency issues as its routing is based on the underlying IPv4, which can be pretty bad for non 6to4 destinations (e.g. normal IPv6 addresses). Moreover, its IPv6 in IPv4 tunnelling technology is likely to be filtered by various intermediate devices in the path. My take is that we shall declare 6to4 over and dead, thank you very much for your service. So I would suggest to filter it. If not, users may get latency issues that will go into support calls unncessarily.


On 14 May 2019, at 11:24, Amos Rosenboim wrote:




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 ?




Amos Rosenboim



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