Question About /etc/shadow

[Tom H]

On Sat, Oct 1, 2016 at 8:07 PM, Jay Ridgley <jridgley2 at austin.rr.com> wrote:
>
> I noticed that he entry for root is slightly different on two of my systems.
> I am wondering which is the more secure.
>
> In the second field each has a single character:
>
> one has !
> the other *
>
> man shadow:
> If the password field contains some string that is not a valid
> result of crypt(3), for instance ! or *, the user will not be able
> to use a unix password to log in (but the user may log in the
> system by other means).
>
> What are those other means and when should ! or * the be used?
>
> In reading I find that ! normally precedes the prior hash. What if the prior
> hash was null (no login required)?

>From "man shadow":

If the password field contains some string that is not a valid result of
crypt(3), for instance ! or *, the user will not be able to use a unix
password to log in (but the user may log in the system by other means).