abstract:War dialing or wardialing is a technique of using a modem to automatically scan a list of telephone numbers, usually dialing every number in a local area code to search for computers, Bulletin board systems and fax machines. Hackers use the resulting lists for various purposes, hobbyists for exploration, and crackers - malicious hackers who specialize in computer security: for guessing user accounts (by capturing voicemail greetings); or locating modems that might provide an entry-point into computer or other electronic systems.