Hi Jeroen probably meant this FAQ item: https://www.sixxs.net/faq/connectivity/?faq=conntracking Also radvd is only needed on a router. It advertises the legit prefix that the clients are supposed to be using for creating their addresses. Plus it of course tells them which route to set so that their traffic is actually being routed. If your Mac is the system that created the tunnel connection it is not really a client in this context. Hence there's no need for radvd. Only if you wanted additional systems to connect to the internet via the sixxs tunnel you'd have to set up a radvd so that those additional systems could auto-configure their addresses properly. Regards M. Reinhold