The first item to discuss when talking about router security is the router’s operating
system (OS). The OS on Cisco routers is called Internetworking Operating System,
or IOS. Most routers will be running an IOS version between 11.x and 12.x. By the
time this book is published,Cisco may have released 13.x. Every OS has vulnerabilities,
and IOS is no exception. These vulnerabilities generally allow an attacker to disable
a router (a denial of service attack),collect information from a router
(information leakage), or reconfigure a router (an actual compromise)....