My problem: I have a bunch of Raspberry Pi computers, all connected via a network switch and USB ethernet port to a "gateway" Raspberry Pi. However, I don't particularly want them all to be internet-connected all of the time, because (1) it's possible there is a slight security risk and (2) my IT folk at work might not like it. OK, I should also mention (3) I tried and failed to get NAT and dnsmasq to work, and don't have time to finish debugging it.
My solution:
I SSH in to my "gateway" Pi (is it ok to call it a gateway even though it's resolutely failing to route any traffic? Never mind...), and from there I can connect to my hidden Pi(s), let's say for arguments sake it's called hiddenpi.local.
Now, I can SSH back again, setting up a SOCKS proxy:
