The role of the CA in this process is to guarantee that the individual granted the unique certificate is, in fact, who he or she claims to be. Certificate authority A trusted third-party organization or company that issues digital certificates used to create digital signatures and public-private key pairs. A digital certificate is commonly used to verify that a user sending a message is who he or she claims to be, and to provide the receiver with the means to encode a reply. Certificate An attachment to an electronic message used for security purposes. Bug A computer program or hardware error that causes recurring malfunctions. Buffer overflow A popular bug-based attack that works by sending more data than the target system is intended to receive at one time.

Brute-force attack An attempt by a hacker to defeat authentication by obtaining a legitimate user's password.

Batch scripts A list of commands executed by a computer’s operating system. It can operate as any of the three types of firewalls. Bastion host Strongly secured devices that have a direct network connection to a public network such as the Internet. Back door An intentional hole in a firewall or security apparatus that allows access around security measures. Authorization The process of giving individuals access to system objects based on their identity. Authentication The process of identifying an individual, usually based on a username and password. Auditing Reading and interpreting log files to identify hacker activity. (Also, public-key encryption) Asymmetric key algorithm An algorithm used for asymmetric encryption. Asymmetric encryption A type of encryption that uses one key to encrypt a message and another to decrypt the message. Application gateways are sometimes known as proxy servers. They are typically implemented through software installed on a specialized server. Application-level gateway Application gateways function at all four layers of the TCP/IP suite. Algorithm A computable set of steps to achieve a desired result.

Address Resolution Protocol (ARP) A network protocol that is used to convert IP addresses to physical network addresses by sending an ARP broadcast to request the address. Access control list (ACL) A list of individual users and groups of users associated with an object, and the rights that the user or group has when accessing that object.

Network firewall security