How to Power On and Shutdown a Remote host with Android?

Question

The title can't be more specific. I'd like you to suggest the best way to send the poweroff instruction, to windows or Linux.

Answer 1

If your host supports wakeup on lan you can use some of these apps.

Answer 2

If your network card can use Wake-On-LAN and/or is supported, and is remotely accessible, then yes, it is quite possible to achieve it (wake-on-lan apps are in abundance on the play store), taking into account of security considerations which is outside of the scope of this site, double check and make sure no other service is on that public facing PC otherwise bad guys will get in and wreak havoc.

Answer 3

Power ON

1. WOL enabled BIOS: In order to power up the remote host, you first have to enable WOL in his bios. The way you have to do this will vary from motherboard to motherboard, sou you'll have to figure it out by your self, or ask Google for some help.
2. Remote Host cable connected to router
3. Application capable of Sending Magic Packets to Remote.host's MacAdress

At the moment I'm using WOLdroid WOL Wake On Lan On remote.host execute:

ifconfig

Detect your remote.host's ehternet board usualy eth0 and save the HW Adress value XX:XX:XX:XX:XX:XX:XX

Enter that number when WOLdroid asks you for a mac adress. And your done.

Now you're able to powerup remotely

Power OFF

1. Prepare the Remote Host:

Remote host with Ubuntu 12.04

Create your private and public key files

To follow these steps you'll have to access your remote host, physically, or using another computer. I'll describe this as if you have physical access to the remote.host

Open a command window and install the ssh protocol:

sudo apt-get install ssh

Create public and private keys using ssh-key-gen

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@remote-host

Now copy the id_rsa.pub to your ~/.ssh/authorized_keys file with this command:

ssh-copy-id -i ~/.ssh/id_rsa.pub remote.host

Now you have to be able to execute the sudo shutdown -P 0 with no password.

Modify /etc/sudoers on remote.host with visudo

That way user "yourusername" can execute the shutdown command with no password asked.
Run:

sudo visudo

By running visudo, it leads to edit /etc/sudoers.
Add the line below to that file.

yourusername ALL = NOPASSWD: /sbin/shutdown

Now we are able to access remotely, and shutdown without passwords asked.

2. Prepare your Android

1. Connect your android to the remote host and with your file explorer copy the id_rsa file located in ~/.ssh/ folder to the Android's SD card.
2. Disconnect your android from the remote host
3. Install a ssh client program. (ex. ConnectBot)
4. Open Connect Bot and go to Manage Pubkeys > Import and select the key you copied later.
5. Go back to Connect Bot's Main Scren and select the ssh protocol from the list and enter loginname@remote.host. Notice that it creates a line in the main screen with the data you input.
6. Push it for a couple of seconds and select edit host.
7. Select Use pubkey authentication and select id_rsa
8. On Post-login automation write sudo shutdown -P 0
9. Go back to you the Main Screen of Connect Bot and we're done!

Now you can Turn on and Shutdown a remote.host :)