Connecting to a network opens up a whole new set of security considerations above and beyond those of protecting accounts and files. Various forms of network protocols, servers, clients, routers, and other network components complicate the picture. To be safely connected requires an understanding of how these components are configured and how they interact.
Connections to networks with potentially unfriendly users should be done with a firewall in place. Connections to a local area network that involves only your company or university may not require a firewall, but still requires proper configuration and monitoring.
In later chapters we will discuss some of these other considerations. We cannot provide truly comprehensive coverage of all the related issues, however, so we encourage you to peruse the references listed in Appendix C.