ipv6/ppp: FreeBSD obtains linklocal on tun0 only

O. Hartmann o.hartmann at walstatt.org
Sun Dec 2 21:46:28 UTC 2018

Hash: SHA512

Am Fri, 30 Nov 2018 14:32:52 +0000
Gary Palmer <gpalmer at freebsd.org> schrieb:

> On Fri, Nov 30, 2018 at 01:12:32PM +0100, O. Hartmann wrote:
> > Hash: SHA512
> > 
> > My ISP is offering IPv6 only "as an experimental feature", so I had to ask to enable
> > the IPv6 stack on my connection. I'm using FreeBSD 12-STABLE as the basis for a
> > router/firewall/PBX system, FreeBSD's onboard ppp client is performing the uplink and
> > authetication and this works well with IPv4 for years for now.
> > 
> > I'm using IPFW as my filtering system, reading the standard /etc/rc.ipfirewall and add
> > some custom rules regarding my setup.
> > 
> > As far as I know, with the IPv4 stack a IPv4 address is obtained automatically, so I
> > would expect the same for IPv6.
> > 
> > I'm new to IPv6 and I've trouble with my provider for a long time now, so there is a
> > slight possibility that my ISP is not truthful on what they say. On the other hand,
> > there is still a high probability that I do something wrong. I need need to send this
> > ahead, before continueing.
> > 
> > When booting off, I see the classic tun0 uplink with
> > 
> > 
> > For IPv6, I only see my local linklocal address, fe80::... 
> > 
> > Checking the log of ppp (/var/log/ppp.log), there is also a fe80:: linklocal address
> > assigned to the variable HISADDR. Somehow, the tun0 never obtains a IPv6 aprefix so
> > far.
> > 
> > Can someone give a tip?  
> I have
> <provider>:
>         shell /sbin/ifconfig tun0 inet6 -ifdisabled -no_radr accept_rtadv
>         shell /sbin/rtsol tun0 &
> in a ppp.linkup file.  The alternative is to use dhcp6c, which also worked
> for my provider.
> (there are other lines in the linkup file also, but I think those are
>  the relevant ones)
> Regards,
> Gary

Thank you very much for this hint! Much appreciated.

With adding those lines to the ppp.linkup script, the outer interface, tun0, now obtains
two valid IPv6 addresses - on is always marked temporary, the other is comprised from
the MAC of the physical interface from which is tun0 is cloned.

But when the ISP is changing the IPs (both IPv4 and IPv6), without any further
actoin I have a bunch of IPv6 addresses over time associated with tun0. 

The documentation lacks in many aspects how to deal with IPv6, especially when it comes
to "well known things from the old IPv4 world". Since DDNS also is still something people
use with IPv6, MYADDR6 doesn't carry the IPV6 address obtained after rtsold has been
started and rtsol tun0 has been issued as described above (MYADDR6/HISADDR6 are assigned
with the linklocal addresses).

Thanks for the help! 

Kind regards,

- -- 
O. Hartmann

Ich widerspreche der Nutzung oder Übermittlung meiner Daten für
Werbezwecke oder für die Markt- oder Meinungsforschung (§ 28 Abs. 4 BDSG).


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