Re: IPv6 default routes / NM vs. kernel autoconfig

[Pavel Simerda <psimerda redhat com>]

> From: "Stuart Gathman" <stuart gathman org>
> The problem is, I don't want the auto IP, *or* the private IPs.

I'm sorry but you would have to express this idea better. DHCPv6
is one of the methods to serve automatic addresses and DNS information.

> I just
> want the DHCP6 IP.  But when I select "DHCP only" in NM, it then

DHCP only is a bad name and the method itself is broken and will most
probably be removed from NetworkManager.

> assigns
> only the DHCP IP, but no route!

If you don't have any route, you don't need the IP either as it will not
be used for any network communication.

> The behaviour I expect with DHCP only
> is to still assign the route from RA.

That'c correct. That's how it works.

> But perhaps the routes cannot
> be separated from the IPs in the kernel?

They mostly are.

> I don't see why not, since the RA routes are *link* scope IPs,
> and don't depend on what global scope IPs are assigned.  I.e.,
> shouldn't setting accept_ra = 0 and
> accept_ra_defrtr =1 work?

Nope. It is not possible to use default gateway from RA that is not
accepted.

> Here are my default routes:
> 
> default via fe80::21a:a0ff:fe3a:a6ff dev wlan0  proto static  metric
> 1
> default via fe80::21a:a0ff:fe3a:a6ff dev wlan0  proto kernel  metric
> 1024  expires 1781sec
> 
> The static one is created by NM - and seems to be what the OP is
> complaining about, as it takes priority over the automatic route,
> which

These are both the same.

> breaks things when the router changes (although nothing a
> disconnect-connect won't fix).

Known bug.

> In either case, they don't depend on any global IP.

Correct.

Cheers,

Pavel