Re: IPv6 tunneling not routing packets

[Andy Ruhl <acruhl%gmail.com@localhost>]

On Sun, Dec 14, 2025 at 10:55 AM Jonathan A. Kollasch
<jakllsch%kollasch.net@localhost> wrote:
>
> On Sun, Dec 14, 2025 at 10:30:12AM -0700, Brook Milligan wrote:
> > I am trying to set up an IPv6 tunnel via Hurricane Electric’s tunnelbroker service, but packets are not routed through the tunnel.
> >
> > After registering the tunnel, their instructions for NetBSD are to configure the network as follows:
> >
> > ifconfig gif0 create
> > ifconfig gif0 tunnel x.x.x.x y.y.y.y
>
> Is the local address here in a public IPv4 prefix that is already
> assigned to another interface on the host?  RFC1918 prefixes or RFC6598
> CGNAT address space (100.64.0.0/10) will (almost certainly) not work for
> protocol 41 tunnels.

Just as a data point: Before my ISP was using IPv6 I set up a tunnel
with HE on my router, then advertised the prefix downward into my
network. My NetBSD systems "just worked" with autoconfig.

If the NetBSD system isn't on the bare internet, I don't think it will
work. You might be able to set up some 1:1 forwarding scheme on your
router to make it work, I don't know.

MTU can become an issue.

Andy