Preventing Sleep on Debian When Network Connections Are Active

When running remote servers or SSH-accessible systems, you don’t want your linux (Debian) machine to suspend while you’re connected or performing remote tasks. This approach blocks system suspend whenever an SSH session is open — without requiring root, sudo, or system-wide configuration.

It is designed for:

What This Does

When you log in via SSH:

  • A background process registers a sleep inhibitor with systemd-logind

  • The inhibitor remains active for the lifetime of the SSH session

  • While the inhibitor is active:

    • Idle suspend is prevented
    • Manual suspend requests are delayed/refused

  • When the SSH session ends:

    • The inhibitor exits automatically
    • Suspend behavior returns to normal

1. Set Polkit policy to skip authentication requirement

By default, using systemd-inhibit --mode=block requires authentication. This is a frustrating experience and can conflict with other on-login hooks (like neofetch/fastfetch) in interactive shells. We can set a policy to skip the authentication requirement specifically for specific actions associated with ssh-inhibit.

  1. Create policy

    sudo nano /etc/polkit-1/rules.d/49-ssh-inhibit.rules

  2. Paste the rule definition

    polkit.addRule(function(action, subject) {
    if (
        subject.active === true &&
        subject.isInGroup("ssh-inhibit") &&
        (
            action.id === "org.freedesktop.login1.inhibit-block-sleep" ||
            action.id === "org.freedesktop.login1.inhibit-delay-sleep" ||
            action.id === "org.freedesktop.login1.inhibit-block-idle"
        )
    ) {
        return polkit.Result.YES;
    }
});

  3. Apply the rule

    sudo chown root:root /etc/polkit-1/rules.d/49-ssh-inhibit.rules
sudo chmod 644 /etc/polkit-1/rules.d/49-ssh-inhibit.rules
sudo systemctl restart polkit

2. Add the SSH login hook to inhibit sleep

  1. Edit /etc/ssh/sshrc

    sudo nano /etc/ssh/sshrc

  2. Add this block near the end:

    # Prevent sleep while SSH session is active
systemd-inhibit \
  --what=sleep \
  --mode=block \
  --who="SSH session" \
  --why="Active SSH connection" \
  sleep infinity \
  </dev/null >/dev/null 2>&1 &

    This inhibits sleep during an SSH connection by blocking sleep:

    • sleep infinity Keeps the inhibitor alive for the duration of the session

    • </dev/null Prevents interactive authentication prompts

    • >/dev/null 2>&1 Keeps SSH login output clean (no banner interference)

    • & Runs in the background so login continues normally

3. Verify active inhibitors

  1. SSH into your Debian host (or log out & log in)

  2. Run:

    systemd-inhibit --list

Check for SSH session ... systemd-inhibit. Example output:

WHO            UID  USER   PID  COMM            WHAT         WHY           >
ModemManager   0    root   1365 ModemManager    sleep        ModemManager n>
NetworkManager 0    root   1251 NetworkManager  sleep        NetworkManager>
UPower         0    root   1642 upowerd         sleep        Pause device p>
GNOME Shell    1000 <USER> 2173 gnome-shell     sleep        GNOME needs to>
SSH session    1000 <USER> 5214 systemd-inhibit sleep        Active SSH con>
...

That confirms your SSH inhibitor is active.

4. Test the inhibitor

Try to suspend manually:

systemctl suspend

You should see something like:

Operation inhibited by "systemd-inhibit (SSH session)"