Yubikey-4 Concepts, Configuration and Use
Logging in to internet sites (and private servers) with just a password is really not acceptable these days, at least for someone (like me) claiming to be interested in IT security. I therefore recently bought a Yubikey-4 authentication token.
Sadly, the documentation available from the manufacturer, and the internet in general, was not very helpful. I have therefore created some extensive notes on the Yubikey-4 which may be useful if you are also considering buying one (or have already done so).