Chapter 1 Network Defense Fundamentals

virus

Computer code that copies itself from one place to another surreptitiously and performs actions that range from benign to harmful

packet filters

Devices or software that block or allow transmission of packets of information based on port, IP address, protocol, or other criteria

return on investment (ROI)

The total value gained after a solution has been deployed. A positive ROI means the solution has solved more problems than it creates

malware

Software, such as viruses, worms, and Trojans, designed to cause harm, allow theft, or otherwise compromise a computer system

integrity

The goal of ensuring the accuracy and consistency of information during all processing (storage, transmission, and so forth)

confidentiality

The goal of preventing intentional or unintentional disclosure of communication between a sender and recipient

authentication

The process of determining authorized users' identities through matching a username and password, a fingerprint or retinal scan, a smart card and PIN, and so on.

defense in depth (DiD)

A layering approach to security that protects a network at many different levels by using a variety of strategies and methods

nonrepudiation

A method for ensuring that the sender can't deny sending a message and the receiver can't deny receiving it

socket

A network connection that uses a TCP/IP port number combined with a computer's IP address

cracker

A person who attempts to gain access to unauthorized resources on a network, usually by finding a way to circumvent passwords, firewalls, or other protective measures

demilitarized zone (DMZ)

A subnetwork of publicly accessible Web, e-mail, and other servers that's outside the LAN but still protected by the firewall

worm

A type of malware that creates files that copy themselves repeatedly and consume disk space. They don't require user intervention to be launched; they are self-propagating.

spyware

A type of malware that includes adware, tracking cookies, dialers, and spam

macro virus

A type of malware that performs the same functions as a macro but tends to be harmful

Trojan programs

A type of program that appears harmless but introduces viruses or causes damage to a computer or system

backdoors

A way of gaining unauthorized access to a computer or other resource, usually through an opening in a program that's supposed to be known only to the program's author

packet monkey

An attacker who's primarily interested in blocking Web site activities through a distributed denial-of-service attack

script kiddies

Attackers (often young people) who spread viruses and other malicious scripts and use techniques to exploit weaknesses in computer systems

availability

Making sure those who are authorized to access resources can do so in a reliable and timely manner

physical security

Measures taken to physically protect a computer or other network device from theft or environmental disasters

password security

Measures to protect passwords, including selecting good passwords, keeping them secure, and changing them as needed. Using multiple passwords, including screensaver passwords and passwords for protecting critical applications, also helps guard against unauthorized access

signatures

combinations of flags, IP addresses, and other attack indicators that are detected by a firewall or IDS