Firewalls

A firewall enforces a security policy, so without a policy, a firewall

is useless. This chapter will help the responsible manager and firewall

administrator create a useful policy for the firewall. Throughout this

chapter, the term firewall refers to the sum of the hardware, software,

policy, and procedures used to implement the firewall policy. A firewall

is not necessarily a single piece of software sitting on a single computer

system.

2.2 Firewall protection

The main function of a firewall is to centralize access control. A firewall

serves as the gatekeeper between the untrusted Internet and the more

trusted internal networks. If outsiders or remote ...