The document discusses basic network security. It identifies networking threats such as viruses, worms and Trojan horses. It describes different methods of attack like denial of service attacks and social engineering. The document also covers security procedures and applications to secure a network, such as defining security policies, installing anti-virus software, and using firewalls. Firewalls can control traffic between networks and help prevent unauthorized access. Effective security requires a combination of technology and a thorough security policy.