Mailbomb: The mail sent to urge others to send massive amounts of email to a single system or person, with the intent to crash the recipient’s system. Mail bombing is widely regarded as a serious offense.Mockingbird: A computer program or process which mimics the legitimate behavior of a normal system feature (or other apparently useful function) but performs malicious activities once invoked by the user.Nak Attack: Negative Acknowledgment – A penetration technique which capitalizes on a potential weakness in an operating system that does not handle asynchronous interrupts properly and thus, leaves the system in an unprotected state during such interrupts.Non-Repudiation: Method by which the sender of data is provided with proof of delivery and the recipient is assured of the sender’s identity, so that neither can later deny having processed the data.Open Security: Environment that does not provide environment sufficient assurance that applications and equipment are protected against the introduction of malicious logic prior to or during the operation of a system.OSI: Open Systems Interconnection. A set of internationally accepted and openly developed standards that meet the needs of network resource administration and integrated network utility.Packet: A block of data sent over the network transmitting the identities of the sending and receiving stations, error-control information, and message. Packet Filter: Inspects each packet for user defined content, such as an IP address but does not track the state of sessions. This is one of the least secure types of firewall.Packet Filtering: A feature incorporated into routers and bridges to limit the flow of information based on pre-determined communications such as source, destination, or type of service being provided by the network. Packet filters let the administrator limit protocol specific traffic to one network segment, isolate email domains, and perform many other traffic control functions.Packet Sniffer: A device or program that monitors the data traveling between computers on a network.Phreak(er): An individual fascinated by the telephone system. Commonly, an individual who uses his knowledge of the telephone system to make calls at the expense of another.Phreaking: The art and science of cracking the phone network.Rootkit: A hacker security tool that captures passwords and message traffic to and from a computer. A collection of tools that allows a hacker to provide a backdoor into a system, collect information on other systems on the network, mask the fact that the system is compromised, and much more. Rootkit is a classic example of Trojan Horse software. Rootkit is available for a wide range of operating systems.SATAN: Security Administrator Tool for Analyzing Networks – A tool for remotely probing and identifying the vulnerabilities of systems on IP networks. A powerful freeware program which helps to identify system security weaknesses.Smurfing: A denial of service attack in which an attacker spoofs the source address of an echo-request ICMP (ping) packet to the broadcast address for a network, causing the machines in the network to respond en masse to the victim thereby clogging its network.Tiger: A software tool which scans for system weaknesses.Tiger Team: Government and industry – sponsored teams of computer experts who attempt to break down the defenses of computer systems in an effort to uncover, and eventually patch, security holes.War Dialer: A program that dials a given list or range of numbers and records those which answer with handshake tones, which might be entry points to computer or telecommunications systems.Worm: Independent program that replicates from machine to machine across network connections often clogging networks and information systems as it spreads.