network firewalls and host-based firewalls

There are two main types of firewalls: network firewalls and host-based firewalls. Network firewalls, such as the software-based Microsoft’s Internet Security and Acceleration (ISA) Server or the hardware-based Nortel Networks Alteon Switched Firewall System, protect the perimeter of a network by watching traffic that enters and leaves. Host-based firewalls, such as Internet Connection Firewall (ICF—included with Windows XP and Windows Server 2003), protect an individual computer regardless of the network it’s connected to. You might need one or the other—but most businesses require a combination of both to meet their security requirements.