[radvd-devel-l] Advertising interface is not "autoconfigured"

Vincent Jardin radvd-devel-l@litech.org
Tue, 22 Jan 2002 19:41:25 +0100

Le Mardi 22 Janvier 2002 06:36, Pekka Savola a =E9crit :
> On Mon, 21 Jan 2002, Venkata Jagana wrote:
> I'm not sure why one would want to autoconfigure eth0 in this case?

I am interested in this feature because I get a dynamic IPv4 global address,=
then my 6to4 prefix changes each time I am connected=2E I can announce this=
prefix to the hosts of my network that get the default route via R via the=
R's link-local=2E

Now, the R's IPv6 routing table is something like:
2002::/16 dev sit0  proto kernel
3ffe::/16 via ::192=2E88=2E99=2E1 dev sit0=20
2000::/3 via ::192=2E88=2E99=2E1 dev sit0=20
fe80::/10 dev eth0  proto kernel=20
fe80::/10 dev sit0  proto kernel=20
ff00::/8 dev eth0  proto kernel=20
ff00::/8 dev sit0  proto kernel=20

then when R gets a datagram from ppp0 for my local network that has the=20
it should be reached via sit0, then it cannot be forwarded to my hosts=2E

Now if eth0 is "autoconfigured" with the prefix:

The R's IPv6 routing table is like the previous one with one more entry:
2002:500d:e52d:beef::/64 dev eth0

Then according to the LPM, any datagram from ppp0 with=20
dest=3D2002:500d:e52d:beef::x can be forwarded via eth0 to my hosts that hav=
an address 2002:500d:e52d:beef::x

> > Before you run radvd on your 'R' box, turn off or disable the forwarding
> > temporarily through
> >
> >    echo 0 > /proc/sys/net/ipv6/conf/<all or ethX>/forwarding
> >
> > Run radvd and then enable forwarding through
> >
> >    echo 1 > /proc/sys/net/ipv6/conf/<all or ethX>/forwarding
> >
> > This is one way of enabling autoconfiguration for router interfaces=2E

Thanks it works=2E But it would be niced if it was a RADVD option=2E
I thought it was a kernel option:

> Changes in radvd 0=2E7=2E1 probably kill this approach (if "all") is used =
> radvd will not start unless "all" forwarding is enabled=2E

Why ?

> Having conf/eth0/forwarding=3D0 is effectively a DoS for the clients for t=
> period it's 0, but in simple scenarios this may not be a problem=2E

Which kind of DoS ?