Cisco® Secure Internet Security Solutions

Basic Management Security

Before delving into specifics regarding how routers should be configured to help avoid attacks, the differences between internal and external devices must be explored. For purposes of this chapter, the authors use the word external as in external interface, meaning that the interface is directly connected to an untrusted entity. This can be the Internet, another company, or even a subsidiary of your own company. An internal interface is one that connects directly to a fully trusted network.

Many factors determine whether an entity is trusted. If there is doubt that the connected entity can be trusted, the authors recommend that the administrator not trust that entity. The initial reaction of many administrators will ...