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Passwordless SSH is a method to login to remote computers by using SSH keypairs, thus avoiding the need to enter a password. It can be handy for remote-controlling LTSP clients, e.g. for rebooting or troubleshooting them.

There are many variations on how to setup passwordless SSH. In the method described here, the server's public SSH key is copied to the authorized keys of the chroot's root account. This way, anyone that has root access to the server, and is able to access the server's private SSH key, will also have root access to the clients.


To install openssh-server and copy the server's public SSH key to all of your chroots, issue the following commands:

for ROOT in /opt/ltsp/*/root; do
    sudo LTSP_HANDLE_DAEMONS=false chroot "${ROOT%/root}" apt-get --yes install openssh-server
    sudo mkdir -p "$ROOT/.ssh"
    sudo chmod 700 "$ROOT/.ssh"
    sudo cp /etc/ssh/ "$ROOT/.ssh/authorized_keys"
    sudo chmod 644 "$ROOT/.ssh/authorized_keys"
    sudo ltsp-update-image --arch $(echo "$ROOT" | cut -d'/' -f4)


After the clients are rebooted, you should be able to control the clients by using /etc/ssh/ssh_host_rsa_key as the identity file.

For example, to login as root on a client, run:

sudo ssh -i /etc/ssh/ssh_host_rsa_key

To shutdown a client, run:

sudo ssh -i /etc/ssh/ssh_host_rsa_key poweroff

See Also

  • UbuntuLTSP - Community Ubuntu LTSP Documentation.

External Links


UbuntuLTSP/PasswordlessSSH (last edited 2010-02-01 10:43:44 by alkisg)