Securing Cisco Perimeter Routers Review

This chapter focused on the IOS features that could be used on the perimeter router as a first line of defense against security threats. The perimeter configuration of the network often includes both a perimeter router and a firewall as the second line of defense. The firewall separates the inside network from the DMZs. The dirty DMZ is protected only by the perimeter router, while the protected DMZ has the firewall and perimeter router between it and the outside.

Network security can be enhanced by disabling unused services, such as CDP, finger, and TCP and UDP small services.