1. Network Firewalls
Network firewalls are a vital component for maintaining a secure environment and are
often the first line of defense against attack. Simply stated, a firewall is responsible for
controlling access between devices, such as computers, networks, and servers. Therefore, the
most common deployment is between a secure and an insecure network (for example,
between the computers you control and the Internet), as shown in Figure 8.1. This chapter
refers to the secure network as the internal network; the insecure network is the external
network