Networking 5.2

Computer Virus

A small program that alters how a computer operates and may damage data, program files, or operating system components.

Computer Worm

A program that copies itself from one system to another over a network without human assistance.

Trojan Horse

A malicious piece of code hidden inside seemingly harmless code, such as an e-mail or application macro.

Denial of Service (DoS) Attack

An attack that bombards a computer site with so many messages that it cannot answer valid requests.

Distributed Denial of Service (DDoS) Attack

A distributed form of denial-of-service attack that bombards a computer site with excessive messages.

E-mail Bombing

Sending an excessive amount of unwanted e-mail to someone.

Botnet

Malicious programs that take over operations on a compromised computer.

Smurfing

A technique that attacks a network by exploiting IP broadcast addressing operations.

Ping Storm

A condition in which the Internet ping program is used to send a flood of packets to a server.

Spoofing

Creating a packet that appears to be something else or to come from someone else.

Phishing

Creating e-mails that appear to come from a legitimate source to trick users into giving up ID and password information.

Pharming

Redirecting an unsuspecting user to a bogus look-alike website.

Rootkit

A program installed deep within a user's operating system that defies detection and takes over the computer.

Keylogger

A software system that secretly captures and records keystrokes made at a user's keyboard.

Patch

A software update issued by a software company to address a known vulnerability.

Physical Protection

Measures that protect computers and systems from environmental damage, unauthorized physical access, power surges, and electromagnetic interference.

Surveillance

Monitoring activities to deter theft and vandalism and provide a record of activities.

Intrusion Detection

A field of study focused on preventing intrusion and determining whether a computer system has been violated.

Honeypot

An indirect form of surveillance in which network personnel create a trap to watch for unscrupulous activity.

Access Control

Deciding who has access to what, including restrictions based on time, day, or location.

Biometrics

Forms of identification that use characteristics such as fingerprints, face prints, retina scans, iris scans, and voice prints.

Access Rights

Permissions that determine who can access a resource and what actions they can perform, such as reading, writing, deleting, printing, copying, or executing.

Auditing

Creating a computer or paper audit to help detect wrongdoing and deter misconduct.

Cryptography

The study of creating and using encryption and decryption techniques.

Plaintext

Data before any encryption has been performed.

Ciphertext

Data after encryption has been performed.

Key

The unique piece of information used to create ciphertext and decrypt ciphertext back into plaintext.

Monoalphabetic Substitution-Based Cipher

A cipher that replaces characters with different characters based on a key.

Polyalphabetic Substitution-Based Cipher

A substitution cipher that uses multiple alphabetic strings to encode plaintext.

Transposition-Based Cipher

A cipher in which the order of the plaintext is not preserved.

Public-Key Cryptography

An encryption technique that uses two keys: a public key to encrypt a message and a private key to decrypt it.

Public Key

The key used to encrypt a message in the public-key cryptography method described in the material.

Private Key

The key used to decrypt a message in the public-key cryptography method described in the material.

Data Encryption Standard (DES)

An encryption standard created in 1977 that takes a 64-bit block of data through 16 levels of encryption using a 56-bit key.

Triple-DES

An encryption method that encrypts data using DES three times, typically using the first key, a second key, and then the first key again.

Advanced Encryption Standard (AES)

The standard selected by the U.S. government to replace DES; it uses 128-, 192-, or 256-bit keys and was designed for fast execution and efficient resource use.

Digital Signature

A method that generates a hash of a document, encodes the hash with the owner's private key, and later checks it against a current hash using the owner's public key.

Pretty Good Privacy (PGP)

Encryption software created by Philip Zimmermann that secures e-mail and other data files using public-key cryptography and digital signatures.

Kerberos

An authentication protocol designed for client/server networks that employs private-key cryptography, using one key for encryption and decryption.

Public Key Infrastructure (PKI)

A combination of encryption techniques, software, and services that supports digital certificates, certificate authorities, and public-key generation, storage, and management.

Digital Certificate

An electronic document, similar to a passport, that establishes credentials during transactions and contains information such as a name, serial number, expiration dates, public key, and issuing authority's digital signature.

Certificate Authority (CA)

A specialized software system on a company network or a trusted third party that issues digital certificates.

Certificate Revocation List

A list used to deactivate a user's certificate.

Steganography

The art and science of hiding information inside other, seemingly ordinary messages or documents.

Spread Spectrum Technology

A secure encoding technique that uses multiple frequencies or codes to transmit data.

Frequency Hopping Spread Spectrum

One of the two basic spread spectrum technologies identified in the material.

Direct Sequence Spread Spectrum

A technology that replaces each binary 0 and binary 1 with a unique pattern or sequence of 1s and 0s.

Signature-Based Scanner

A virus scanner that looks for particular virus patterns or signatures and alerts the user.

Terminate-and-Stay-Resident Program

A program that runs in the background and constantly watches for viruses and their actions.

Multi-Level Generic Scanning

A combination of antivirus techniques that includes intelligent checksum analysis and expert system analysis.

Firewall

A system or combination of systems that supports an access control policy between two networks and can limit transactions entering or leaving a system.

Packet Filter Firewall

A firewall that filters out or allows certain IP addresses or TCP port numbers, essentially functioning as a programmed router.

Proxy Server

A more advanced firewall that acts as a doorman into a corporate network; external transactions requesting access must pass through it.

Application-Layer Firewall

A firewall that inspects packets using the application layer of the TCP/IP protocol suite and identifies the application to which each packet belongs.

Wired Equivalency Protocol (WEP)

The first security protocol used with wireless LANs; it had weak 40-bit static keys and was too easy to break.

Wi-Fi Protected Access (WPA)

A wireless security protocol that replaced WEP and introduced dynamic key encryption and mutual authentication for wireless clients.

WPA2 (IEEE 802.11i)

A wireless security protocol that allows keys, encryption algorithms, and negotiation to be dynamically assigned and incorporates AES encryption.