Source : Free On-Line Dictionary of Computing

wardialer
     
         Almost certainly a shortened version of "WarGames
        dialer", from the film {WarGames}.
     
        1. {carrier scanner}
     
        2. A program which attempts to break a {password} of known
        length by iterating thru all possible combinations of
        characters that could make up that password.
     
        This approach is not feasable for cracking most passwords
        these days.  However, as late as the mid-1980s, some
        long-distance companies required only very short numeric
        access codes (e.g. five digits) to verify the identity of
        their customers.  Wardialers were created which would, running
        unattended, call up long-distance providers' local connect
        numbers and iteratively try possible access codes.  Codes
        which worked were logged for later illicit use.
     
        These wardialers had a high success rate because of the small
        range of possibilities to iterate through, e.g. 10000 for a
        five digit access code, compared to hundreds of trillions of
        combinations for an eight-character alphanumeric code.
     
        Long-distance providers soon required longer passwords and
        took advantage of technology for rapidly tracing the phone
        numbers that wardialers were being run from, such that running
        wardialers became pointless and dangerous.
     
        (1997-03-16)