Practical UNIX and Internet Security, 3rd Edition

Chapter 10. Modems and Dialup Security

In this age of the Internet, there are still many reasons to be concerned with the security of modems and dialup services. Because dialup services are easy to set up and cheap to maintain, there are many that are still in operation—some of which have been in operation for a decade or more. Likewise, even with the wide availability of local area networks and high-speed connections, there are many reasons that you might wish to set up your own modem-based network connections:

• You can have administrators do some remote maintenance and administration when they are “on call.” Hardwired modems frequently allow access to communications and infrastructure equipment even when network connections are down.

• If some people in your organization travel frequently, or if they travel to rural areas, they might want to use a modem to access the computer when they’re out of town, rather than incurring the expense and complication of dealing with nation-wide Internet service providers. A direct connection to your company’s modems may be more private as well.

• When properly configured, a dialup service can provide limited access to the system for remote users without incurring all of the risks of an open network connection.

• If people in your organization want to use the computer from their homes after hours or on weekends, a modem will allow them to do so. Some organizations believe that they can provide their own dialup service in a manner that is more cost-effective ...