On Thu, Mar 14, 2019 at 09:06:12PM +0100, Sebastian Benoit wrote:
> Claudio Jeker(cje...@diehard.n-r-g.com) on 2019.03.14 11:53:29 +0100:
> > On Thu, Mar 14, 2019 at 11:46:10AM +0100, Otto Moerbeek wrote:
> > > On Thu, Mar 14, 2019 at 10:43:03AM +0100, Claudio Jeker wrote:
> > > 
> > > > On Thu, Mar 14, 2019 at 10:36:58AM +0100, Otto Moerbeek wrote:
> > > > > Hi,
> > > > > 
> > > > > So i have a little IPv6 problem. 
> > > > > 
> > > > > I have a machine in colocation that has IPv6. I have my home cable
> > > > > modem connection that does not have it.
> > > > > 
> > > > > So I thought: I make my own tunnel. First I tried gif(4), that worked,
> > > > > but only after some fighting with mtu settings on all hosts on my home
> > > > > net via rad.  Performance was kinda bad. So I'm looking for an
> > > > > alternative. I thougt: IPSEC should be able to do this.
> > > > > 
> > > > > I have a flow from my locally created IPv6 net to any and vice versa.
> > > > > THe flow itself works. 
> > > > > 
> > > > > There I ran into the trouble that you cannot specify a default
> > > > > gateway, since my remote gw (the host in colo) it is not reachable
> > > > > according to route(8).
> > > > > 
> > > > > How does one solve the default route problem?  I never really
> > > > > understood how routing works in the presense of IPSEC flows.
> > > > > 
> > > > 
> > > > IPSec flows steal the traffic away before it is being sent out. You 
> > > > still
> > > > need routes in place to get to this point though. In your case adding a
> > > > dummy default route should work. Never tried but I think you should be
> > > > able to use the loopback for this and add a route like 'route add -inet6
> > > > default ::1' also don't forget to enable net.inet6.ip6.forwarding
> > > > 
> > > > -- 
> > > > :wq Claudio
> > > > 
> > > 
> > > Indeed, that seems to work. Thanks,
> > > 
> > 
> > You may need to use pf to block the routed IPv6 traffic on the loopback
> > or you may end up with a routing loop when the IPsec flow is not present.
> > You can use a 2nd loopback or maybe even a vether(4) and use the link
> > local address as the default gateway then dropping this traffic should be
> > trivial.
> 
> Why not "route add -inet6 default ::1 -blackhole" ?
> 

Because that would drop the packets in the forwarding path before hitting
the ipsec code. At least I thought this was the case. If that works even
better :)

-- 
:wq Claudio

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