A B C D E F G H I J K L M N O P Q R S T U V W X Y Z ACK Acknowledgement - A response from a receiving computer to a sending computer to indicate successful receipt of information. TCP requires that packets be acknowledged before it considers the transmission complete. Access Control - Techniques for limiting access to resources based on authentication information and access rules. Address Masquerading - Configuring a network interface with an IP address intended for another system. This undermines access control mechanisms based on network addresses. Address Spoofing - Counterfeiting IP datagrams in a way that causes the receiving system to believe they originated from a host other than the actual sender. Agent - The Software routing in an SNMP-managed device that responds to get and set requests and sends trap messages. AH Authentication - A planned security enhancement to IP that provides sending system authentication and datagram integrity, but not confidentiality. See also ESP. Anonymous Remailer - A program that removes all traces of an e-mail messages' actual sender and location before forwarding the message to its intended recipient. API Application Programming Interface - A high-level language binding that enables a programmer to easily use functions in another program. Application Gateway - A system used to restrict access to services, or specific functions within services, across a firewall boundary. Application Layer - The protocol layer used by applications (like Telnet, FTP, and so on) that rides atop the services provided by the transport and network layers. ARP Address Resolution Protocol - A protocol in the TCP/IP suite used to resolve a network (IP) address to its link-layer address. Attack - An electronic assault (typically unprovoked) that attempts to somehow break the targets systems, networks and security mechanisms. Authentication - A systematic method for establishing proof of identity between two or more entities, usually users and hosts. Authorization - The predetermined right to access an objective or service based on authentication information. BSD Trust - A trust mechanism whereby one host trusts the identity of users of another system without requiring them to authenticate with passwords. Camping Out - Creating a safe undetected spot for hacking, storing or retrieving information, and/or creating another way to get in at a later time upon admission into a network. Certificate Authority (CA) - A trusted entity that digitally signs certificates in order to validate ownership of public keys. Chroot - A Unix system call used to intentionally restrict a server's view of the host's file system away from sensitive files. Ciphertext - Plaintext converted into a secretive format through the use of an encryption algorithm. An encryption key can unlock the original plaintext from ciphertext. Confidentiality - Assurance of privacy, often achieved on the internet through the use of encryption. Connection - A logical path between two protocol modules that provides a reliable delivery service. Connection-Oriented Services - A delivery service that provides a well-ordered data stream, including provisions that guarantee against lost, out-of-sequence, and duplicate packets. Connectionless Service - A delivery service that treats each packet independently from all others before and after it. Can result in lost, duplicate, or out-of-sequence packets. Cookie - A secret password or key. Covering Tracks - An intruder who exists without getting caught by removing, replacing or disabling log files that would otherwise indicate a security breach. Cracker - A hacker who does not respect the computers she/he hacks on. From CRiminal hACKER. Cryptanalysis - The Science of analyzing and breaking secure communication. Cryptography - The science of enabling secure communication through encryption and decryption. Cryptology - The study of secretive communication, including both cryptography and cryptanalysis. Datagram - A packet of data and its delivery information usually associated with connectionless service. Decryption - The inverse of encryption; the process of converting ciphertext into plaintext. Denial of Service - Internet or IP services disrupted by a flood of phony traffic that clogs the provider's network. SYN Flood, Ping o' Death and Ping Flooding are some examples of Denial of Service attacks. DES Data Encryption Standard - Adopted by the U.S. government in 1977 as the federal standard for the encryption of commercial and sensitive yet unclassified government computer data. Diffie Helmann or Exponential Key Exchange - A concept related to public-key cryptography, it provides a mechanism for setting up a secret but unauthenticated connection between two parties. Digital Signature - An unforgeable electronic signature that authenticates a message sender and simultaneously guarantees the integrity of the message. DNS Domain Name System - A distributed database system used to map IP addressees to host names. The DNS also provides mail exchange information. Encryption - The process of converting data from an easily understandable format (plaintext) into what appears to be random, useless gibberish (ciphertext) until it is later decrypted. ESP Encapsulating Security Payload - A planned security enhancement to IP. Extranet - A collaborative network that uses Internet technology to link businesses with their suppliers, customers, or other businesses. The shared information can be accessible only to the collaborating parties or can be publicly accessible. finger - A Unix command that provides potentially useful information about a user and sometimes a server. It should always be disabled. Firewall - One or more packet filters and gateways that shield "internal" trusted networks from "external" untrusted networks such as the Internet. FQDN Fully Qualified Domain Name - The combination of a system's host and domain name. FTP File Transfer Protocol - An application-layer protocol used mostly to copy files between systems. Also refers to the client program that implements the protocol. FTPD FTP daemon - The server program that implements the FTP protocol. Hacker - A person who illegally gains access to your computer system. HASH - See One-Way Hash Header - Data carried at the beginning of a packet or other type of message that contains information vital to delivery. HTTP Hypertext Transfer Protocol - An application-layer protocol used to deliver text, graphics, sound, movies, and other data over the WWW via the friendly hypertext interface of a Web browser. HTTPD HTTP daemon (server) - Generically refers to any WWW server. ICMP Internet Control Message Protocol - An IP maintenance protocol that monitors and communicates control information, including notification of unreachable destinations, between network participants. IDEA International Data Encryption Algorithm - IDEA is a block cipher operating on a 64-bit plaintext blocks. The key is 128 bits long. Integrity - The current condition of data compared to its original, pristine state. Integrity Check - A mechanism for ensuring that data has not been tampered with by adding, to removing from, or otherwise modifying its contents. Often achieved through digital signatures and one-way hash functions. Internet - The world's largest collection of networks that reaches universities, government research labs, commercial enterprises, and military installations in many countries. IP Internet Protocol - Along with TCP, one of the most fundamental protocols in TCP/IP networking. IP is responsible for addressing and delivering datagrams across the Internet. IP Address - The 32-bit address that uniquely identifies a node on an IP network. ISO International Standards Organization - An international body founded to draft standards for network protocols. Java - A object-oriented language based on C++ that allows developers to develop platform independent applications. Joyriding - Commandeering a phone service or ISP connection, allowing the intruder to exploit these services without paying for them. Kerberos - A distributed authentication system, developed at MIT as part of Project Athena, which identifies users, client, and server applications to each other. KEY - One of all possible values that can be applied to plaintext with an encryption algorithm to produce ciphertext, or vice versa. LAN - A communications network that spans small geographical areas. Layered Protocols - Protocols that are "stacked" one atop another, whereby "lower" protocols transparently provide services to "higher" ones. MIB Management Information Base - A database of objects that represent various types of information about a device. Used by SNMP for device management purposes. MIT-MAGIC-COOKIE-1 - The universally available but infrequently used mechanism for the X Windows System that can help to prevent unauthorized access to the user's graphical display, keyboard, and pointing device. MTA Message Transfer Agent - An entity that shoulders responsibility for transferring e-mail messages to their destination, or at least one step closer to it. Name Resolution - The process of mapping a host name to an IP address. DNS is the Internet's primary system for resolving host names. Network Layer - On the Internet, the layer that implements IP, and provides services to the transport layer. NFS Network File System - A weakly authenticated distributed file system built on RPC that was developed by Sun Microsystems. NFS clients mount remote server directories and then access them as if they were local. See also Secure NGS. NIS Network Information Service - A naming service developed by Sun that provides a directory service for network and host information. NNTP Network News Transfer Protocol - Used for the distribution, inquiry, retrieval, and posting of articles on the Usenet news system. One-Time Passwords - User passwords that are used only one time to establish authentication, and are therefore not subject to snooping and replay attacks. One-Way Hash - A function that takes plaintext of arbitrary length as input and outputs a small fixed-length value that is a unique "fingerprint" of the message. OSI Open Systems Interconnection - A set of ISO standards that define the framework for implementing network protocols in seven layers. Packet - A unit of protocol data; often used as a synonym for segment and datagram. Packet Filter - A networked device that scans packet header information to determine whether packets should be blocked or allowed to pass through the filter. PEM Privacy Enhanced Mail - A standard for message encryption and the authentication of message senders. PGP Pretty Good Privacy - A collection of programs for various operating systems mainly used to exchange encrypted and authenticated e-mail messages. Phreaker - A phone hacker. From PHone fREAKER. Ping Sweep - A network reconnaissance technique that uses ICMP echo (pings) to map a network. Ping o' Death - A denial of service attack, the Ping o' Death can crash or reboot a large number of systems by sending a "ping" message of greater than 65,536 bytes (the default size is 64 bytes). Plaintext - Message text that is freely readable and understandable by anyone; the opposite of ciphertext. POP3 Post Office Protocol version 3 - An e-mail protocol primarily used to transfer new messages from a central mail server to users' workstations. Port - 16-bit identifiers used by TCP and UDP that serve to specify which process or application is sending or receiving data. Port Sweep - A network reconnaissance technique that determines services available on a host computer. Protocol - A set of rules used to govern the transmission and receipt of data. Public-Key Cryptosystem - A cryptosystem in which one-half a single keypair is used for encryption and the other half for decryption. Punch - To create a hole in a device or network allowing legal or illegal entry. "r" Commands - Remote commands used in Unix between trusted servers. When used between trusted hosts, the trusted server does not need a password to be accessed from the trusted server. Rlogin, rsh and rcp have the most serious security implications. Reconnaissance - Scoping out potential targets in order to zero in on the most lucrative least protected target. Relay - A program that passes unstructured data to and from an application client and server, across an intervening firewall. Replay Attack - Playing back another party's packets or other messages recorded in a prior snooping attack in an effort to a accomplish the same or similar results achieved earlier. Resolver - Client software that enables access to the DNS database. RFC Request for Comment - Documents written for and by the Internet community that describe Internet protocols, surveys, measurements, ideas and observations. RIPEM Riordan's Internet Privacy Enhanced Mail - A specific and well-known implementation of the PEM standard. Route - The path that network traffic takes from its source to its destination. Router - Special-purpose computing devices dedicated to delivering packets between communicating endpoints. RPC Remote Procedure Call - A weakly authenticated mechanism that allows an application to call a procedure that executes on a remote machine. See also Secure RPC. RSA Rivest-Shamir-Adleman - The first (and today, still the most popular) public-key cryptosystem to offer both encryption and digital signature functionality. Screening Router - A router with packet filtering capabilities enabled. Secret-Key Cryptosystem - A cryptosystem in which the same key is used for encryption and decryption. Secure NFS - An enhanced version of NFS built on Secure RPC that allows for authenticated and encrypted access to files stored on a remote server. Secure RPC - A version of RPC enhanced to support DES encryption over the network connection. Segment - A protocol data unit consisting of part of a stream of bytes being sent between two machines. Also includes information about the current position of the stream and a checksum value. Server Filter - A host-based firewall that logs and filters client access to server applications. Shadow Passwords - User passwords stored in a database accessible only by privileged system administrators. Shoulder Surfing - Finding out what a user is typing by looking over their shoulder, and watching the keyboard or monitor. S-HTTP Secure HyperText Transfer Protocol - An extension of HTTP with security enhancements designed to enable WWW-based commerce. SKIP Simple Key management for Internet Protocols - An authentication/encryption system that secures the network at the IP packet level. SMTP Simple Mail Transfer Protocol - A protocol used to transfer electronic mail messages from one machine to another. SNMP Simple Network Management Protocol - A protocol used to manage local networks on the Internet. SNMP enables a management station to configure, monitor and control network devices such as routers. Snooping Attack - Passively eavesdropping network traffic in order to capture valuable data or secrets, such as user passwords. Social Engineering - To use lies, deceit, play acting and verbal cleverness to trick legitimate users into divulging the secrets of the system. Socket - A bidirectional pipe for incoming and outgoing data that enables an application program to access the TCP/IP protocols. Source Route - A route identifying the path a datagram must follow, determined by the source device. Squatting - See Camping Out. SSL Secure Sockets Layer - A security layer sandwiched between the application and transport layers. SSL transparently protects application-layer protocols (like HTTP, for which it was originally conceived) and data, with little effort on the part of the application developer. Static Passwords - In contrast to one-time passwords, user passwords that are reused many times for authentication purposes. Because they are reusable, static passwords are subject to snooping and replay attacks. TCP Transmission Control Protocol - A connection-oriented transport protocol that provides reliable, full-duplex data transmission between two entities, often a client and a server application. Telnet - Remote terminal protocol that enables a terminal attached to one host to log in to other hosts, as if directly connected to the remote machine. TFTP Trivial File Transfer Protocol - A no-frills, unauthenticated protocol used to transfer files. TFTP depends on UDP and often is used to boot diskless workstations. Transport Layer - On the Internet, the layer that implements TCP and UDP over the network layer. Trojan Horse - A piece of code, embedded in an otherwise benign program, that is used to attack a site. TTL Time-To-Live - The maximum number of router hops that a datagram can experience on a network before it should be discarded. Used to prevent packets from looping endlessly. UDP User Datagram Protocol - A connectionless transport protocol. Delivery is not guaranteed, nor is it guaranteed that datagrams will be delivered in the proper order. WAN Wide Area Network - A physical communications network that spans large geographical distances. WANs usually operate at slower speeds than LANs. Wrapper - The wrapper package performs two basic functions: it logs requests for internet services and provides an access control mechanism for Unix systems. WWW World Wide Web - A cohesive and user-friendly view of the Internet through many protocols, especially HTTP. X Window System - A graphical windowing system developed at MIT that enables a user to run applications on other computers and view the output. CyberCop Home · Product & Solutions · Resources Security Services · Events · Customer Center