Authentification
From Blue-IT.org Wiki
Yubikey
SSH
Generally: only use key based authentification with webserver logins!
vim /etc/ssh/sshd_config
# Authentication: [...] PermitRootLogin without-password StrictModes yes RSAAuthentication yes PubkeyAuthentication yes IgnoreRhosts yes RhostsRSAAuthentication no HostbasedAuthentication no
PermitEmptyPasswords no ChallengeResponseAuthentication no PasswordAuthentication no # <<<< !!!! X11Forwarding no UseLogin no
UsePAM no <<<< !!!!