• Choose a category
• All
• Classic-Fiction

duplexed hard drives Two hard drives to which identical information is written simultaneously. A dedicated controller card controls each drive. Used for fault tolerance.

duplicate servers Two servers that are identical, for use in clustering.

Dynamic Host Configuration Protocol (DHCP) A protocol used on a TCP/IP network to send client configuration data, including IP address, default gateway, subnet mask, and DNS configuration, to clients. DHCP uses a four-step process: Discover, Offer, Request, and Acknowledgement. See also default gateway, Domain Name Service (DNS), Transmission Control Protocol/Internet Protocol (TCP/IP).

dynamic packet filtering A type of firewall used to accept or reject packets based on their contents.

dynamic routing The use of route-discovery protocols to talk to other routers and find out what networks they are attached to. Routers that use dynamic routing send out special packets to request updates from the other routers on the network as well as to send their own updates.

dynamically allocated port A TCP/IP port that is not constantly used but accessed by an application when needed.

E

EAL See Evaluation Assurance Level (EAL).

eavesdropping Any type of passive attack that intercepts data in an unauthorized manner—usually in order to find passwords. Cable sniffing, wiretapping, and man-in-the-middle attacks are eavesdropping attacks.

ECC See Elliptic Curve Cryptosystem (ECC).

EF See exposure factor (EF).

electromagnetic interference (EMI) The interference that can occur during transmissions over copper cable because of electromagnetic energy outside the cable. The result is degradation of the signal.

Elliptic Curve Cryptosystem (ECC) A type of public key cryptosystem that requires a shorter key length than many other cryptosystems (including the de facto industry standard, RSA).

EMI See electromagnetic interference (EMI).

Encapsulating Security Payload (ESP) A header used to provide a mix of security services in IPv4 and IPv6. ESP can be used alone or in combination with the IP Authentication Header (AH).

encoding The process of translating data into signals that can be transmitted on a transmission medium.

encryption The process of converting data into a form that makes it less likely to be usable to anyone intercepting it if they can’t decrypt it.

encryption key A string of alphanumeric characters used to decrypt encrypted data.

enticement The process of luring someone.

entrapment The process of encouraging an attacker to perform an act, even if they don’t want to do it.

enumeration An attempt to gain information about a network by specifically targeting network resources, users and groups, and applications running on the system.

escalation The act of moving something up in priority. Often, when an incident is escalated, it’s brought to the attention of the next highest supervisor. See also privilege escalation.

Ethernet A shared-media network architecture. It operates at the Physical and Data Link layers of the Open Systems Interconnection (OSI) model. As the media access method, it uses baseband signaling over either a bus or a star topology. The cabling used in Ethernet networks can be coax, twisted-pair, wireless, or fiber-optic.

Ethernet address See MAC address.

Evaluation Assurance Level (EAL) A level of assurance, expressed as a numeric value, based on standards set by the Common Criteria Recognition Agreement (CCRA).

event Any noticeable action or occurrence.

exposure factor (EF) A calculation of how much data (or other assets) could be lost from a single occurrence. If all the data on the network could be jeopardized by a single attack, the exposure factor is 100 percent.

external threat A threat that originates from outside the company.

extranet Web (or similar) services set up in a private network to be accessed internally and by select external entities, such as vendors and suppliers.

extrusion Examining data leaving a network for signs