How many people and companies use Cisco routers? You do not need to be a system integration engineer to know the specific figure. Baidu will tell you the answer. Do you panic when knowing that a backdoor targeting Cisco routers may affect most models? An experienced network administrator knows that the firmware of routers is not frequently upgraded. Once an attacker gets the knack of exploiting such backdoors, he or she can use them against those routers in a long time. Are you scared of that?