+[The new plan]
+
+It appears that people want to be able to use secnet on mobile
+machines like laptops as well as to interconnect sites. In particular,
+they want to be able to use their laptop in three situations:
+
+1) connected to their internal LAN by a cable; no tunnel involved
+2) connected via wireless, using a tunnel to protect traffic
+3) connected to some other network, using a tunnel to access the
+internal LAN.
+
+They want the laptop to keep the same IP address all the time.
+
+Case (1) is simple.
+
+Case (2) requires that the laptop run a copy of secnet, and have a
+tunnel configured between it and the main internal LAN default
+gateway. secnet must support the concept of a 'soft' tunnel where it
+adds a route and causes the gateway to do proxy-ARP when the tunnel is
+up, and removes the route again when the tunnel is down.
+
+The usual prohibition of packets coming in from one tunnel and going
+out another must be relaxed in this case (in particular, the
+destination address of packets from these 'mobile station' tunnels may
+be another tunnel as well as the host).