The serial to ethernet app. note / module are nice but what about the reverse:

Using 2 modules to connect 2 lan networks together by bridging them over rs232.

Detect all packets and keep a MAC list of received packets, and forward the packets over rs232 for the MAC's that are not in the list.(destination's not heard on that ethernet side will be forwarded over rs232 to the other side )

I guess this should work.


The rs232 side can then be replaced by 2 wireless data 1Watt modules in the 900Mhz range to create a long range wireless PC connection (several miles). (eg http://www.aerocomm.com/docs/User_Manual_AC4790.pdf )