Here's how to configure ppp and dropbear in order to setup an ssh through serial port: First of all, ppp support needs to be enabled in kernel, so start kernel menuconfig and enable the following voice: Device Driver -- Network Device Support PPP Support for sync tty ports Then pppd and dropbear packages need to be added in buildroot, so using buildroot menuconfig find and enable: Target packages -- Networking applications dropbear pppd (just in case activate also filtering and radius) At this point when you start the system, dropbear won't be able to generate an rsa key beacause the filesystem is read only, so you need to generate a new rsa key and restart dropbear with the new key: Kill the running dropbear process, and create a new rsa key in the tmp folder: dropbearkey -t rsa -f /tmp/myrsakey then restart dropbear: dropbear -B -r /tmp/myrsakey Since by default buildroot has no root password, when you start dropbear you need to use the options -B, otherwise blank password on ssh login won't be allowed. If like me, you use Qt Creator, I recommend you to set a root password or you won't be able to use QtCreator's deploy and debug functionalities. Of course if you have a root password there's no need to use -B option. Now your ssh server is ready, you just need to start pppd to establish a TCP/IP connection through the serial port. Prepare 2 terminal windows, one with minicom running and connected to the board, the other empty. The following command messes up the serial connection, so when strange symbols appears on the terminal with minicom I know that pppd started and I just close the terminal. pppd /dev/ttySC2 115200 lock nodetach noauth debug /dev/ttySC2 is my serial port, yours might be different, details on the options can be found at this page: https://ppp.samba.org/pppd.html So the terminal is messed up, just close it and on the other terminal give the following as fast as you can (you better paste this line :D ): sudo pppd /dev/ttyACM0 115200 lock nodetach noauth debug localIp : targetIp I usually use 190.0.0.1 for the local Ip and 190.0.0.254 for the target Ip but this is up to you :) This is the end, now on a new terminal just type: ssh root@ targetIp and enjoy your ssh connection. You can also use scp to transfer files between host and target.
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