Whenever I change IPs or networks or whatever, I usually forget an open ssh session somewhere, which then stalls and I can't disconnect it.
No big deal, right? Hit enter a few times, then ~., and I should disconnect. Except I don't. Just hangs there waiting around for some slow network timeout. Why? It seems the time when using ~. to disconnect would be most useful is when the network is down, and that's precisely when it doesn't work.
