Network+™: Study Guide, Fourth Edition

8.3. Using Firewalls

It is popular these days to connect a corporate network to the Internet. By connecting your private network (only authorized users have access to the data) to a public network (everyone connected has access to the data), you introduce the possibility for security break-ins. For this reason, firewalls are implemented. A firewall protects a private network from unauthorized users on a public network.

Firewalls are usually a combination of hardware and software. The hardware is typically a computer or a dedicated piece of hardware (often called a black box) that contains two network cards. One connects to the public side; the other, to the private side. The software controls how the firewall operates and protects your network. ...