On 2015/09/16 17:32, Denis Fondras wrote:
> On Wed, Sep 16, 2015 at 03:38:22PM +0100, Stuart Henderson wrote:
> > On 2015/09/16 09:39, David Hill wrote:
> > > So I need to attach an IP somewhere.  Both the FreeBSD and NetBSD in the
> > > u6rd manpage say I need an IPv6 address on tun0.
> > > 
> > >    NetBSD 5.1
> > >      # ifconfig tun0 create
> > >      # ifconfig tun0 inet6 2001:db8:cb00:7101::1/32
> > 
> > This works if you put it into tap mode (ifconfig tun0 link0) but that
> > is probably not what your application needs.
> > 
> > Same if you remove the /32 prefix.
> > 
> > Interestingly doing the same on gif or gre does work.
> > 
> 
> Setting link0 sets IFF_MULTICAST.
> 
> The main difference between Free and OpenBSD is that tun(4) interfaces are
> created with IFF_MULTICAST with FBSD :
> 
> if_tun.c from FreeBSD (line 380) :
> ifp->if_flags = IFF_POINTOPOINT | IFF_MULTICAST;
> 
> IPv6 requires multicast :)
> 
> Denis
> 

Ah yes: and in6_ifattach() has

484         if ((ifp->if_flags & IFF_MULTICAST) == 0)
485                 return (EINVAL);

Presumably this is more fallout from "no IPv6 by default".

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