In deciding how to protect information systems, the security manager must consider internal threats from disgruntled employees and threats from outside the system. Smart cards with PINS are a major access control device; the user can keystroke the number into the terminal or the terminal can read magnetic strips on the card. Managers may want additional protection offered by PPDs which perform an authentication function and are independent of the computer. PPDs can be used at both ends of the communications circuitry or as a one-end device. They have the added capability of restricting the number of sign-on attempts per dial-in connection to negate brute force attacks. Other advantages of PPDs include call-back features and the capability to hide the computer so the unauthorized caller cannot identify the kind of machine the PPD is protecting. Another innovation in dial-up protection is the security modem. The article discusses drawbacks to PINS and factors that determine whether a computer system requires security protection. A chart lists commercially available PPDs.