[ale] IPv6 routing issues

JK jknapka at kneuro.net
Fri Sep 4 12:02:30 EDT 2009


Michael H. Warfield wrote:
> On Thu, 2009-09-03 at 09:53 -0600, JK wrote:
>> Hi ALE,
> 
>> I installed the freenet6.net IPv6 tunnel client (tspc) on my Ubuntu box,
>> and it establishes a tunnel successfully using my account credentials.
>> However, I can't get a reply from ping6'ing any remote host -- "No
>> route to host".
> 
>> So, hmm, I guess it's a routing problem.  And in fact "ip route list"
>> reveals no IP6 routing info.  Google is rife with advice to set up a
>> default IP6 route via the tunnel device:
> 
>>    ip route add ::/0 dev sit1
> 
>> But this does not help at all.  Further, the route does not even seem
>> to be added (even though the "ip route" command succeeds): subsequently,
> 
>>    ip route list dev sit1
> 
>> returns no entries, and a plain "ip route list" shows nothing that
>> looks like the IP6 route I just added.
> 
> 	Try "ip -6 route ls".  Without the -6 it's only going to show you the
> v4 routes.
> 
> 	Sounds like IPv6 has been initialized properly OR you have IPv6
> forwarding enabled.  It's a peculiarity (a deliberate peculiarity) that
> the kernel will not honor the IPv6 default route if IPv6 forwarding is
> enabled.  This was, ostensibly, to prevent the accidental routing of
> link-local, site-local, and scoped multicast beyond their designed
> scopes.
> 
> 	Try this instead: "ip -6 route add 2000::/3 dev sit1"
> 
> 	See if that works any better for you.


Nope.  I also disabled IP6 forwarding, and no joy :-(  Plus I do
actually want this machine to be a router.

"ip -6 neigh list" returns nothing, even when my tunnel is up. Should
this worry me?

Also, the v6 address on the sit1 interface is 2001:blah:blah::blah/128,
which seems to indicate that maybe I didn't get the /64 I (thought I)
asked for?  Their info page makes a distinction between the prefix
assigned to the tunnel vs the "delegated" prefix, but I don't understand
the distinction.

Probably I need to read more :-/

Thx,

-- JK



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