A firewall is a security system that prevents outside users from accessing private network resources. There are two main types of firewalls: packet-level and application-level. Packet-level firewalls allow or deny access based on IP addresses but are susceptible to IP spoofing. Application-level firewalls use additional proxy software to filter data based on content but can cause speed decreases and be susceptible to inside attacks. Successful attacks like the Sasser worm and IP spoofing demonstrate the importance of firewalls for network security.

1. FIREWALLS Antonio Arthur

4. Diagram 1

7. VisNetic Firewall 2.2, Software

9. SonicWall Pro 2040, Hardware Price: $2,000 Data Transfer Rate: 200 Mbps Port Qty: 5

10. Common Network Layout