Closing a Hung SSH Session

How does one close an SSH session that has hung or disconnected from the server?

Use the key sequence ~. (tilde followed by a dot, typed at the beginning of a new line). For more information, check the SSH manual:

man ssh

Background

I was happily working on my system, accessing my test box remotely. Suddenly, there was darkness—or what most people call a power outage. Since my UPS was in the repair shop, my machine shut down and left me with a frozen SSH session upon rebooting and reconnecting.