Before installing the SunScreen 3.1 Lite software, you should first determine your network security policy. For a more thorough discussion of this topic, read Computer Security Policies and SunScreen Firewalls by Kathryn M. Walker and Linda Croswhite Cavanaugh. Additional resources are listed in the Preface.
In brief, considerations when creating a security policy are:
what services do employees need to access?
what services do customers need to access?
will you allow Internet access, and if so, what services do users need to access?
what type of threat are you trying to protect your company from?
Do you need to use network address translation (NAT)?