Linux/YubiKey

1. https://www.yubico.com/works-with-yubikey/catalog/debian/
2. https://wiki.debian.org/Smartcards/YubiKey4
3. https://packages.debian.org/search?suite=default&section=all&arch=any&searchon=names&keywords=yubikey
4. https://www.linode.com/docs/security/authentication/two-factor-authentication/how-to-use-yubikey-for-two-factor-ssh-authentication/
5. https://wiki.archlinux.org/index.php/YubiKey
6. https://gist.github.com/tr3buchet/5105747