Hello. Can anyone shed any light as to what this error means?
sshd: error: PAM: authentication error for illegal user xxxxx from 66.xxx.xxx.xxx
Thanks for the help.
If means you have your SSH port open on WAN and someone tried to connect and login, but failed.
In general it is not a good idea to allow your SSH port to be exposed to the world. If you must allow access, at least move the port to something else (222, 34890, 41383, some other random port) and enable key-only auth. That will both reduce the likelihood that someone will find the service, and that nobody can just keep trying passwords to get in.