PPP
Setup:
launch host with:
pppd -detach crtscts lock proxyarp <local IP>:<remote IP> /dev/ttyUSB0 115200
launch client with:
pppd -detach crtscts lock defaultroute <local IP>:<remote IP> /dev/ttyUSB0 115200
make sure IP forwarding is enabled on the host:
sysctl -w net.ipv4.ip_forward=1 cat /proc/sys/net/ipv4/ip_forward
useful websites:
http://www.ducea.com/2006/08/01/how-to-enable-ip-forwarding-in-linux/
http://www.tldp.org/HOWTO/PPP-HOWTO/direct.html