Kill Apple Remote Desktop via ssh

http://www.alecjacobson.com/weblog/?p=2783

I tried to remote control my work machine from home using Apple Remote Desktop and got the following error:

Apple Remote Desktop or another administration application is currently running.

The problem was that I had left the same Apple Remote Desktop client running on my work machine. To solve this I sshed to that machine and issued:

killall "Remote Desktop"

Update: You can then use remote desktop to reopen the Apple Remote Desktop client and go to preferences > Security and check “Allow control of this computer when this application is running”