Organizations of all sizes need to mitigate the risk of insider threats. Misconduct by authorized users represents a grave threat to an organization. According to the 2005 Computer Security Institute and Federal Bureau of Investigation Computer Crime and Security Survey, organizations reported that computer intrusions from inside sources accounted for nearly half of all incidents. You can secure your network perimeter with intrusion detection systems, firewalls, and virus scanners, but don't neglect to monitor authorized users. The Linux Audit daemon can help you detect violations of your security policies.