How do I enable debug logging for SSHD (SSH)?

Question

How do I enable debug logging for SSHD (SSH)?

Answer

Note: The management and maintenance of configurations for services that cPanel does not create or provide, such as SSHD, are best handled by a systems administrator with the skills, training, and expertise required to do so for you. 

1. Log in to the server as the root user via SSH or the WHM Terminal.

2. Make a backup of the existing configuration with the following command:

   # cp -v /etc/ssh/sshd_config{,$(date +.%Y-%b-%d-%H-%M-%S)}

3. Open the configuration with a text editor of your choice:

   CONFIG_TEXT: /etc/ssh/sshd_config

4. Add the following configuration to the file:

   CONFIG_TEXT: LogLevel DEBUG3

5. Carefully inspect the configuration to see if any duplicate LogLevel directives existed before your addition. If there is another configuration already present, comment it out by placing a hash symbol (#) at the start of the line:

   CONFIG_TEXT: #LogLevel INFO

6. Restart the SSH Daemon (SSHD) with the following command to load the new configuration:

   # /scripts/restartsrv_sshd --restart

7. The logs for SSHD can be reviewed with one of the following commands:

   # less /var/log/secure

   # journalctl -u sshd