I'm looking for suggestions on the best mechanism to do the following.

  I want to run "rtsold" at boot time, and also leave it as a daemon. 
If, at any time, I don't have a v6 default route, then I'd like to configure
stf0 up with my an IP address that is known to be public (e.g. if I see that
I got 192.168.1.2, then forget it, there is likely a NAT).

  This way, i should always have IPv6 connectivity, it is can be available.

  (as a further abuse of the ESPUDP proposals, I wonder if we can convince
ngwg that prefix 2003: means to send it with SPI=3, ESP/over/UDP. That
would likely even work behind NATs, if one can find out what one's externally 
visible IP address is going to be)

] Train travel features AC outlets with no take-off restrictions|gigabit is no[
]   Michael Richardson, Solidum Systems   Oh where, oh where has|problem  with[
]     mcr@solidum.com   www.solidum.com   the little fishy gone?|PAX.port 1100[
] panic("Just another NetBSD/notebook using, kernel hacking, security guy");  [