Recently I want to add an account in the way that, it can only be login via SSH key.
Initially, I thought that NL means that even with SSH key setup, the login will still fail. But I am wrong.
So with testing with NL and NP status, I realize the following behaviour
1) login with passwd - failed ( of course)
2) login via su ( both works )
3) login via ssh ( both works )
The only difference is, with NL , the password in /etc/shadow for that account is set as NP
with NP, the password in /etc/shadow for that account is empty.
So what is the fundamental difference between NL and NP ? they seems to behave the same for me ?