Enabling Dial-Up Passwords

If you want to limit who can dial in and connect, dial-up passwords allow you to control who accesses the systems remotely. To enable the use of dial-up passwords, you must examine the file /etc/login.defs and see that DIALUPS_CHECK_ENAB is set to Yes.

Two files contain the dial-up information:

•  /etc/dialups contains the ttys (one per line, with the leading “/dev/” removed). If a tty is listed, dial-up checks are performed.

•  /etc/d_passwd contains the fully qualified path name of a shell, followed by an optional password.

If a user logs into a line that is listed in /etc/dialups and his shell is listed in the file /etc/d_passwd, he will be allowed access only by entering the correct dial-up password.

The command dpasswd assigns passwords to the shells in the /etc/d_passwd file.

From Here…

You can find more information about security issues in the following chapters:

•  Chapter 10, “Managing User Accounts,” discusses the issues relating to creating and maintaining user accounts on Linux.

•  Chapter 11, “Backing Up Data,” describes how to set up and maintain backups of your system.