You don't see the attacks, because you're not running a server, and the attacks aren't logged unless you're running a firewall that logs its attacks. Also, many forms of security are illusory at best. Take user and server passwords. Network administrators are often either too lax or too overworked to purge terminated employees off the system, force people to change passwords often, or lock users out after a number of failed log-on attempts. Lockout, even for 15 minutes, can be a big deterrent, and the log files indicate that a security violation is in progress.
Many network administrators have no idea how vulnerable they are to cracking attacks.
I've tried some, and they work. But cracking tools are also invaluable for security audits, because they quickly expose users whose passwords are too easy or don't conform to your company's security policy. My tests show that long, mixed-case passwords with special characters can add days or weeks to a cracker's task. One of the most notorious and, by contrast, most helpful crackers is L0phtCrack, which cracks Windows NT passwords from a workstation. One reader, a Windows NT system administrator, tried it from a no-privileges Windows 95 machine and was astounded to find that it uncovered 85 percent of his office's passwords in a mere 20 minutes and that it unlocked all but two in 24 hours.