If a network interface offers IPv4 as well as IPv6, by default Ubuntu’s SSH server listens on both IP versions. In order to restrict access to protocol version 4 you have to comment in the line #ListenAddress 0.0.0.0 in your /etc/ssh/sshd_config. #ListenAddress :: ListenAddress 0.0.0.0 Restart SSH service for the changes to take effect. sudo service […]