You can define special dial-in passwords on selected tty lines, requiring selected classes of users to enter dial-in passwords. Logging information, including the last time of connection, is stored just as with normal logins.
Specific dial-in lines that require passwords are defined in the file /etc/dialups. The format is one tty device name per line, for example:
/dev/tty1A /dev/tty5CThe actual dialup passwords are kept in the file /etc/d_passwd. The password format is the same one used in /etc/passwd. The first field (``user name'') in /etc/d_passwd is not a user name, but the name of a shell program (for example, /bin/sh) used in /etc/passwd. If the login shell of the user attempting to log in (on a tty line listed in /etc/dialups) is listed in /etc/d_passwd, then the user is prompted for the dial-in password stored in /etc/d_passwd.
Use this command line for creating a dial-in password:
passwd -m dialname
Change the password for dialup shell dialname (listed in /etc/d_passwd). If dialname begins with a slash (/) the entire shell name must match. Otherwise the password for every shell whose basename is dialname is changed. Only the superuser can change a dialup shell password.