Understanding SSH on the Raspberry Pis

By default, Raspberry Pis using Raspi-LTSP do not by default allow ssh access.
It though can be extremely useful for debugging to be able to access a Raspberry Pi over SSH.
There is though a few things you need to be aware of.

• The Raspi-LTSP users are not stored on the Raspberry Pis. They are stored on the server.
  
• The Raspberry Pi verifies the provided credentials when a user enters them by using an SSH connection to the server instead of storing the credentials locally.
  
• SSH is enabled by default, although there are no valid user accounts enabled. To SSH into a Raspberry Pi on Raspi-LTSP, you must enable the root account using sudo ltsp-chroot --arch armhf passwd. Don't forget to recompress the operating system after changing it (can be found in other/NBD-recompress in Raspi-LTSP). You can log in as root.
  

Troubleshooting

I don't know what the IP address of the Raspberry Pi is?

Open a terminal on the Raspberry Pi and enter hostname -I. It should print the current IP address of the Raspberry Pi.

I am getting key errors when trying to connect to the Raspberry Pi or getting other random errors.

Sometimes the ssh keys are not generated correctly on Raspi-LTSP clients.
To regenerate the keys, reconfigure the openssh-server using sudo ltsp-chroot --arch armhf dpkg-reconfigure openssh-server. Don't forget to recompress the operating system after changing it (can be found in other/NBD-recompress in Raspi-LTSP).