Disable Cisco Discovery Protocol (CDP) service at device level. Rationale: The Cisco Discovery Protocol is a proprietary protocol that Cisco devices use to identify each other on a LAN segment. It is useful only in network monitoring and troubleshooting situations but is considered a security risk because of the amount of information provided from queries. In addition, there have been published denial-of-service (DoS) attacks that use CDP. CDP should be completely disabled unless necessary. Impact: To reduce the risk of unauthorized access, organizations should implement a security policy restricting network protocols and explicitly require disabling all insecure or unnecessary protocols.
Solution
Disable Cisco Discovery Protocol (CDP) service globally. hostname(config)#no cdp run Default Value: Enabled on all platforms except the Cisco 10000 Series Edge Services Router