====== Slattach ======
<code>
PC1:
 1, sudo slattach -s 19200 -p slip -dL /dev/ttyUSB0
 2, sudo ifconfig sl0 10.0.0.1/24 up
 3, sudo route add default gw 10.0.0.254 sl0

PC2:
 1, sudo slattach -s 19200 -p slip -dL /dev/ttyUSB0
 2, sudo ifconfig sl0 10.0.0.2/24 up
 3, sudo route add default gw 10.0.0.254 sl0
</code>

https://stackoverflow.com/questions/5890505/socat-tunnel-ip-through-tty