questions about routing via tun(4) interfaces

[Chuck Musser <cmusser%sonic.net@localhost>]

I'm trying out NetBSD as a router where one of the interfaces is a tun(4). This
works when I bring the tunnel up, give it an address and add a route to the
remote through it like so:

route add -net 192.168.1.0/24 -link -interface tun0

My questions are:

1. What does the -link keyword do here? Without it, the route command fails
   with "tun0: bad data". The route(8) man page mentions -link briefly, but
   it says that subsequent addresses are expected to link-level addresses
   in numeric format. I don't that applies to this particular case.

2. When the route is created, "netstat -rn -f inet" displays it like this:

   192.168.1/24       74.75.6e.30.0.e.0.0.0.0.0.0 US          -        -      -  tun0

   What is that long address in the second column? I think the idea is that
   the route is through a link, but that is not the MAC of any interface on
   this system.

3. Routing didn't work until t gave the tun a local address. I picked an arbitrary
    one, 10.0.0.1, which is not on either the local nor remote networks. Why is it
   needed?

Thanks for any insight,

Chuck