Fine-tuning this level of security is important. That approach is risky indeed in today's cyberworld. On an almost weekly basis the press reports newly discovered security holes in the most modern network and operating systems. The World Wide Web is filled with sites that specialize in sharing information on how to hack into computer systems. The instantaneous ease of access to information that the Net provides is a mixed blessing.
Harmful knowledge is just as readily shared as good news.
In its simplest implementation a firewall is a dedicated-purpose computer that serves as a traffic cop between the Internet and your company. It allows your company to be very selective about what communication takes place between your employees and the Internet. As with other security tools, firewalls are a mixed blessing. A tightly configured firewall can easily prevent employees from engaging in perfectly proper Internet communications. While the default configuration options of most firewalls recognize this fact and avoid excessive restrictions, there is enough variation in cyberspace that precise configuration of a corporate firewall is an ongoing process, not a one-time installation.