Red Hat ENTERPRISE LINUX 4.5.0 Reference Manual page 326

Chapter 16. Pluggable Authent...
password required pam_unix.so shadow nullok use_authtok
This line specifies that if the program changes the user's password, it should use the
component of the
pam_unix.so
module has determined that the password needs to be changed.
pam_unix.so
The argument
shadow
password.
The argument
nullok
blank password, otherwise a null password is treated as an account lock.
The final argument on this line,
order when stacking PAM modules. This argument tells the module not to prompt the user for a
new password. Instead, it accepts any password that was recorded by a previous password
module. In this way, all new passwords must pass the
passwords before being accepted.
session required pam_unix.so
The final line specifies that the session component of the
session. This module logs the username and the service type to
beginning and end of each session. It can be supplemented by stacking it with other session
modules for more functionality.
The next sample configuration file illustrates
#%PAM-1.0 auth required pam_nologin.so auth required pam_securetty.so auth
required pam_env.so auth sufficient pam_rhosts_auth.so auth required
pam_stack.so service=system-auth
First,
pam_nologin.so
except for root.
auth required pam_securetty.so
The
pam_securetty.so
This effectively disallows all root
safeguards.
Tip
To log in remotely as the root user, use OpenSSH instead. For more information,
302
module to do so. This only happens if the
tells the module to create shadow passwords when updating a user's
instructs the module to allow the user to change their password from a
use_authtok
checks to see if
/etc/nologin
module prevents the root user from logging in on insecure terminals.
attempts due to the application's limited security
rlogin
, provides a good example of the importance of
pam_cracklib.so
pam_unix.so
/var/log/messages
module stacking for the
auth
exists. If it does, no one can log in
password
portion of the
auth
test for secure
module manages the
at the
program.
rlogin