stderr: Permission denied (publickey,gssapi-keyex,gssapi-with-mic) code example

Example: permission denied (publickey,gssapi-keyex,gssapi-with-mic,password).

I had the same issue while using vagrant. So from my Mac I was trying to ssh to a vagrant box (CentOS 7)

Solved it by amending the /etc/ssh/sshd_config PasswordAuthentication yes then re-started the service using sudo systemctl restart sshd

Hope this helps.