Install the Advanced Server Access server agent on Ubuntu or Debian

To install and use the server agent, you’ll need to add the repository signing key, create a package resource list entry linked to the repository signing key, and update the available packages.

To install the agent:

  1. Some versions of Debian may require you to install GnuPG:

    sudo apt-get install gpg

  2. Add the Advanced Server Access repository key:

    curl -fsSL | gpg --dearmor | sudo tee /usr/share/keyrings/scaleft-archive-keyring.gpg > /dev/null

  3. Create a package resource list entry:

    echo "deb [arch=amd64 signed-by=/usr/share/keyrings/scaleft-archive-keyring.gpg] linux main" | sudo tee -a /etc/apt/sources.list.d/scaleft.list > /dev/null

  4. Update the list of available packages:

    sudo apt-get update

  5. Install the Advanced Server Access server tools:

    sudo apt-get install scaleft-server-tools

The sftd daemon starts automatically.

On systems that use the systemd system and service manager and the journald system service, you can enter the following command to verify that the daemon is running:

journalctl -u sftd

On systems that don't use journald for log management, you can check /var/log/sftd.log to verify that the daemon is running.


For servers running Ubuntu 20.04 or later, you have to allow certificate authorities (CAs) to use the ssh-rsa algorithm to sign certificates. To do this, add the following line to your OpenSSH daemon file (which is either /etc/ssh/sshd_config or a drop-in file under /etc/ssh/sshd_config.d/):

CASignatureAlgorithms ssh-rsa

Next steps

Verify server enrollment