How could I shutdown a remote host, in my network thru ssh, with a local host?

The question is simple.
What would be the script I would have to use to shut down a computer in my network thru ssh.

Normaly i would go to command line and:

ssh desktop
delik@desktop's password:
delik@desktop:~$ sudo shutdown -P 0

To power on I created a file and wrote:

wakeonlan xx:xx:xx:xx:xx:xx

And gave it the executable bit

That way to power on it requires only a double click. Would i be capable of doing the same to shutdown?

3 Answers

For the following I am assuming that the user you are going to use in remote-host is the same you use in local-host.

In order to do what you want, you have to first authorize your local-host to connect to you remote-host with no password. To do that you have to (as described here):

1. Install ssh:

   sudo apt-get install ssh

2. Create public and private keys using ssh-key-gen on local-host by entering this command in your localhost:

   ssh-keygen

   You should save the generated key in:

   /home/yourusername/.ssh/id_rsa

   Press enter twice to leave the passphrase empty.

   Your identification has been saved in /home/yourusername/.ssh/id_rsa.
   Your public key has been saved in /home/yourusername/.ssh/id_rsa.pub.
   The key fingerprint is:
   XX:XX:XX:xX:XX:xX:XX:XX:XX:XX:XX:XX:XX:XX yourusername@local-host

3. Copy the public key to the remote-host using ssh-copy-id:

   yourusername@local-host$ ssh-copy-id -i ~/.ssh/id_rsa.pub remote-host
   yourusername@remote-host's password:
   Now try logging into the machine, with:
   ssh remote-host

   and check in .ssh/authorized_keys to make sure we haven't added extra keys that you weren't expecting.

   Note: ssh-copy-id appends the keys to the remote-host’s /home/yourusername/.ssh/authorized_key.

4. Login to remote-host without entering the password:

   ssh remote-host
   yourusername@remote-host:~$

   Access to remote-host with no password. Success!

Now you have to be able to execute sudo shutdown -P 0 with no password. You can do that by modifying /etc/sudoers on remote-host with visudo. That way, user yourusername can execute the shutdown command with no password asked.

1. Login to the remote-host:

   ssh remote.host

2. Run:

   sudo visudo

   By running visudo, you edit /etc/sudoers in a safe manner.

3. Add this line to the file:

   yourusername ALL = NOPASSWD: /sbin/shutdown

4. After doing that, get back to your local-host, create a new empty file and paste this line, modifying the remote-host's name:

   ssh remote.host sudo shutdown -P 0

5. Save and close the file, right-click on it to go to its Properties → Permissions, and tick Execute this file as a program.

Script done!

2

For me on my 18.04 server, the keygen and sudoers edits did not work on their own. Finally, after a big hassle, I managed to remote shutdown my server with the following command:

plink -batch -ssh -P 222 -t user@server -pw XXX "sudo -S shutdown"

I edited sudoers so that:

user ALL=(ALL) NOPASSWD:/sbin/shutdown

You can use an user-account with a keyfile instead of a password (so you don't have to type in the password to login). You can also give the user a "default shell" that is not bash or sh, but "shutmedown.sh" or something like this, which will exec your shutdown-code.

7

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