In Ubuntu or Debian, a default OpenSSH server will display OpenSSH version alongside with Ubuntu/Debian distribution banner: $ telnet repeater.my 172.16.91.20 22 Trying 172.16.91.20… Connected to 172.16.91.20. Escape character is ‘^]’. SSH-2.0-OpenSSH_6.6.1p1 Ubuntu-2ubuntu2 You can hide the identifying part of Ubuntu-2ubuntu2 from the server banner by editing /etc/ssh/sshd_config file, and adding “DebianBanner no” either at … Continue reading How to Hide OpenSSH Ubuntu version from Nmap and other scanners