On Sat, Aug 27, 2016 at 11:41:12PM +0000, Håvard Rabbe wrote:

> Im using tinc to bridge networks together. And im using ebtables to block 
> dhcp traffic for ipv4 on each node in tinc. One of my nodes have recently 
> began using ipv6. The isp is using auto configuration to give out ipv6 
> addresses. The problem is that every computer in my bridged network is 
> getting ipv6 addresses from that node.
> The other computers behind the other nodes have no use for ipv6 addresses it 
> gets through the tinc tunnel.
> 
> Is there a way to block ipv6 auto configuration traffic entering the tinc 
> tunnel on each node?

You should be able to block those packets in the FORWARD chain. IPv6
autoconfiguration is done using ICMPv6 packets with types 133 and 134,
see: https://en.wikipedia.org/wiki/Neighbor_Discovery_Protocol. So do
something like:

ip6tables -A FORWARD -i <vpn interface> -p icmpv6 --icmpv6-type 133 -j DROP
ip6tables -A FORWARD -o <vpn interface> -p icmpv6 --icmpv6-type 134 -j DROP

-- 
Met vriendelijke groet / with kind regards,
     Guus Sliepen <[email protected]>

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