Disable remote root logon to sshd: a protocol error occurred. Change of username or service not allowed

When studying Linux security, I encountered a problem. I originally planned to modify Linux to directly log on to the root user, and then modify it to the sshd configuration file.

Nano/etc/ssh/sshd_config

After modifying # permitrootlogin yes to permitrootlogin no, save and restart sshdservice sshd restart.

Create a common user

Useradd unixbar passwd unixbar

In the securecrt remote tool

The server has disconnected with an error. server Message reads: a protocol error occurred. change of username or service not allowed: (shang1, ssh-connection)-> (Shang, ssh-connection)

Such a similar error.

This is caused by securecrt settings. Change your username to unixbar. After doing so, you can disable remote root login:

Disable remote root logon to sshd: a protocol error occurred. Change of username or service not allowed