Remotely Log into a MacOS X Machine

While it is a rare event, sooner or later MacOS X will lock up on you. It may even be one of those hard freezes where nothing works, not even Force-Quit (Command-Control-Escape).

If you were clever enough to enable remote login, you can go to any terminal on the network and gracefully restart the frozen computer rather than give it the Three-Finger-Salute (Command-Control-Power).

Open the System Preferences application and select the Sharing Tab. Under Application activate the "Allow remote login" checkbox. This is all you need to do on the MacOS X computer. If it crash/freezes you can now securely log in from another computer on the network.

Remote login under MacOS X is through ssh. If you wish to log into the frozen machine from another MacOS X or Linux computer, open a terminal and type:

ssh -l user_name IP_ADDRESS

or in my specific example:

ssh -l coyle 10.201.35.7

By the way, that's the letter "L" as in Larry, not the number one. The first time you do this on each remote computer you will receive a minor warning:

The authenticity of host '10.201.35.7' can't be established. Are you sure you want to continue connecting (yes/no)?

Feel free to type 'yes' and at the prompt enter your password to start your encrypted login session. Now that you have access to the frozen machine, to restart it type:

sudo reboot

After entering your password, the machine will quit all processes, unmount the partitions, and safely reboot.

If you are on a remote machine running Classic MacOS, you will need to download a Terminal program that supports ssh. I recommend Nifty-Telnet SSH. It's free and works great. To setup a secure telnet session open a new connection.

Give the Shortcut a name and IP number to access, then use the Popup menu to select SSH-3DES.

Hit to connect and enter your user name and password in to the window shown below.

This will give the familiar terminal prompt from MacOS X. From here, follow the instructions above to restart the computer.

Setting up SSH-Telnet is something you always wish you had done BEFORE you found yourself staring at a frozen computer screen. With time, you may even become experienced enough to shutdown just the runaway process eliminating the need to reboot the computer altogether! This is UNIX after all.

Source
Michael Coyle
www.resexcellence.com