nixCraft → Tutorials → Linux → OpenSSH Tip: Check Syntax Errors before Restarting SSHD Server OOpenSSH (OpenBSD Secure Shell) is a default secure shell for encrypted communication sessions over a computer network using the ssh protocol. Usually, you log in using ssh and makes changes to its configuration file /etc/ssh/sshd_conf over a remote session. If there is an error in configuration, the serv