This is a test of NAT-traversal.

The network is configured as follows:

    ROAD
      |
      NIC---EAST--SUNRISE

A NAT is setup on NIC that does traditional NAPT on the
NORTH network. 

This more complicate test has ROAD extrude a single IP address
from EAST's network. 

East is configured with proxy_arp set, such that east will respond
to ARPs' for addresses that it has a route for, that are in east's
network.

There is also another conn with *subnetwithin=0.0.0.0/0 configured, so
this tests the overlap detection code that we suspect might not be perfect
yet.