Re: Temporary IPv6 addresses vs. netgroups

[Ignatios Souvatzis <is%netbsd.org@localhost>]

On Thu, Jan 31, 2013 at 10:27:53PM +1100, Darren Reed wrote:
> is%netbsd.org@localhost wrote:
> >On Thu, Jan 31, 2013 at 09:57:17PM +1100, Darren Reed wrote:
> >
> >>I wonder if focusing on addresses is the correct thing to do.
> >>
> >>Should we in fact be focusing on network interfaces instead?
> >
> >No. At least that's a different problem.
> >
> >We started talking about multiple addresses on the same LAN, some being
> >randomized and only intended for pseudonymous access to untrusted peers.
> >
> >The desire is to have an application tell it doesn't want to use them;
> >think address-authorized lpr or nfs.
> 
> What about being able to give an address a "metric" that enabled
> a sorting order for address selection?
> 
> # ifconfig bge0 alias 192.168.1.1 netmask 255.255.255.0 weight 15
> # ifconfig bge0 alais 10.1.1.1 netmask 255.255.252.0 weight 50

Well, but we'd need that per-application or per-socket! Sometimes
we want one, sometimes the other.

The problem with temporary addresses is that they occupy exactly
the same subnet as the fixed/dhcp/autoconfigured addresses we want
to avoid or prefer, depending on application; so per-process routing
tables don't help, either.

The more proposals I read, the more I think that the original problem
can easiest be solved by allowing interested applications to bind, 
where this isn't yet possible.

To make this generic, we'd need a generic tag list per address, or
as the next-to-minimal solution a flag "temporary" and a method to
prefer permanent vs. temporary. A hack would be to have a socket option
that selects longest vs. shortest lifetime addresses.

        -is