"Failed password" and "Invalid user" - Secure Shell Server

I installed ssh-server on Ubuntu 18.04.01.

When I try to access the server with PuTTY the error "access denied" is shown. The server log says "failed password" and "invalid user".

I also changed "PermitRootLogin yes" in sshd_config. But it still doesn't work. I am trying to figure out the problem since hours.

Does somebody know, what configuration has to he changed?

2 Answers

If you still have access to the server's terminal, use the command "cut -d: -f1 /etc/passwd" to see all users.

You must restart sshd after updating the config file.