Cisco CCNA Security 640-553 IINS Tutorials Part-2

Asymmetric encryption Employs a two-key technology: a public key and a private key. Often this is simply called public key encryption. In this key pair, the public key may be distributed freely, whereas the private key must be closely guarded. If it is compromised, the system as a whole will fail. The way that public key encryption works is that the public key is used to encrypt the data. After it is encrypted, only the private key can decrypt the data. The opposite is also true.

Auditing The process of recording the actions of an authenticated user. An example is tracking how long a user is authenticated on the network and the resources he or she works with while on the network, as well as the length of usage. Auditing can produce a history of network usage on the part of a given user or users.

Authentication The confirmation that a user who is requesting a service is a valid user of the network services requested. Authentication is accomplished by presenting an identity and credentials. These might be such things as passwords, one-time tokens, or digital certificates.

Authentication, Authorization, and Accounting (AAA) These three primary services give a network security as well as a record of user activity. AAA identifies who the user is, what the user can access, and what services and resources the user is using when he or she makes a connection with a server.

Authentication server A RADIUS server (such as Cisco Secure ACS) that validates a client’s credentials against its user database.

Authenticator A device (such as a Cisco Catalyst switch) that provides access to a network. The authenticator typically does not authenticate the supplicant. Rather, the authenticator acts as agateway, relaying authentication messages between the supplicant and an external authentication server.

Authorization The granting of specific types of service to a user, based on his or her authentication, the services he or she is requesting, and the current system state.

AutoSecure An automated approach to applying security best practices to a router that is invoked from the CLI.

Auxiliary VLAN The VLAN used by a Cisco IP Phone to carry voice traffic is often called an auxiliary VLAN.

Availability The availability of data is a measure of its accessibility. For example, if a server were down only 5 minutes per year, it would have an availability of 99.999 percent (that is, “five nines” of availability).