Короче, запускаю sacat на двух концах null-модемного кабеля:
root@ne-vlezay80:/home/ne-vlezay80# socat -d -d /dev/ttyACM0 TUN:192.168.1.2/24,up
2017/04/21 02:07:05 socat[3699] N opening character device "/dev/ttyV3" for reading and writing
2017/04/21 02:07:05 socat[3699] N creating tunnel network interface
2017/04/21 02:07:05 socat[3699] N starting data transfer loop with FDs [5,5] and [6,6]
root@ne-vlezay80:/home/ne-vlezay80# socat -d -d /dev/ttyACM0 TUN:192.168.1.1/24,up
2017/04/21 02:07:05 socat[3699] N opening character device "/dev/ttyV3" for reading and writing
2017/04/21 02:07:05 socat[3699] N creating tunnel network interface
2017/04/21 02:07:05 socat[3699] N starting data transfer loop with FDs [5,5] and [6,6]
root@ne-vlezay80:/home/ne-vlezay80# socat -d /dev/ttyV2 TUN:192.168.1.1/24,up
2017/04/21 02:56:56 socat[4368] E write(6, 0x10045f0, 1): Invalid argument
