===========================WEB_TERMS================================
ABI/Inform A database of articles in more than 800 business-related
periodicals and specialty publications since 1986.
Abuse of Privilege user performs an action that they should not
have, according to organizational policy or law.
Access Control Lists Rules for packet filters (typically routers) that
define which packets to pass and which to block.
Access Router A router that connects your network to external Internet.
Typically, this is your first line of defense against
attackers from outside Internet.By enabling access control
lists on this router,able to provide protection for
all of the hosts``behind'' that router,
effectively making that network a DMZ instead
of an unprotected external LAN.
Access Provider The company that provides you with Internet access and,
in some cases, an online account on their computer
system.
Acoustic Coupler A type of modem which converts digital signals into sound
for transmission through telephone lines, and performs
reverse operation when receiving such signals.
Acoustic couplers generally have cups for telephone
handset.
Active Window The top or front window in a multiple window environment.
A/D Converter A device used to convert analog data to digital data.
Analog data is continuously variable, while digital data
contains discrete steps.
Additive Primaries
Red, green, and blue are primary colors of light from
which all other colors can be made.
Address Resolution Conversion of an IP Address to corresponding low-level
physical address.
AIX Advanced Interactive Executive - IBM's version of Unix.
Aliasing Visibly jagged steps along angled or object edges, due to
sharp tonal contrasts between pixels.
Analog Continuously variable signals or data.
Anonymous Login Convention (FTP)
Standard username (anonymous) and password (guest) which
allows login within FTP for purpose of retrieving an
unprotected file.
ANSI American National Standards Institute. This organization
is responsible for approving U.S. standards in many
areas, including computers and communications.
Standards approved by this organization are often called
ANSI standards (e.g., ANSI C is version of C language
approved by ANSI).
Application Software that lets users do relatively complex tasks, as
well as create and modify documents. Common application
types include word processors, spreadsheets,
database managers, and presentation graphics programs.
Application backdoors Some programs have special
features that allow for remote access. Others contain
bugs that provide a backdoor, or hidden access, that
provides some level of control of the program.
Application-Layer Firewall
A firewall system in which service is provided by
processes maintain complete TCP connection state and
sequencing. Application layer firewalls
often re-address traffic so that outgoing traffic
appears to have originated from the firewall, rather
than the internal host.
ARA AppleTalk Remote Access. A protocol (and product) that
provides system-level support for dial-in (modem)
connections to an AppleTalk network. With ARA, you
can call your desktop Mac from a PowerBook and remotely
access all available services - files, printers, servers,
e-mail, etc.
Archie An information system offering an electronic directory
service for locating information in Internet that is
automatically updated. The best known use of archie is
for
scanning a database of contents of more than 1000
Anonymous FTP sites around world with more than 2,100,000
file names.
ARP Address Resolution Protocol. Used to dynamically discover
low-level physical network hardware address that
corresponds to high level IP Address for a given
host, for instance. ARP is limited to physical network
systems that support broadcast packets that can be heard
by all hosts on network. See also Proxy ARP.
ARPANET Advanced Research Projects Agency NETwork. A pioneering
long-haul network funded by ARPA, an agency of U.S.
Department of Defense responsible for
development of new technology for military. It served as
basis for early networking research as well as a central
backbone during development of
Internet. The ARPANET consisted of individual packet
switching computers interconnected by leased lines.
ASCII American (National) Standard Code for Information
Interchange. A standard character-to-number encoding
widely used in computer industry.
Associate
Linking a document with program that created it so that
both can be opened with a single command.
AV Audio-Visual. AV Macintosh models have video-capture
hardware and have sophisticated sound (and video)
recording capabilities.
AU sounds A type of audio format used in World Wide Web.
B or Return to Quick Index
B
Authentication determining the identity of a user that is attempting to
access a system.
Authentication Token A portable device used for authenticating a user.
Authentication tokens operate by challenge/response,
time-based code sequences, or other
techniques. This may include paper-based lists of
one-time passwords.
Authorization determining what types of activities are permitted.
once authenticated a user, they may be authorized
different types ofaccess or activity.
Backbone Network used to interconnect several networks together.
Backup file In Windows 95, a compressed version of original file and
its locations created by Backup.
Bandwidth The capacity of transmission medium stated in bits per
second or as a frequency. The bandwidth of optical fiber
is in gigabit or billion bits per second range, while
ethernet coaxial cable is in megabit or million bits per
second range.
Baseband System A baseband system transmits signals without converting
them to another frequency and is characterized by its
support of one frequency of signals. Ethernet-based
networks inside campus buildings are transmitted via
baseband coaxial cable, with ethernet being only service
supported by coaxial cable.
Bastion Host A system that has been hardened to resist attack, and
which is installed on a network in such a way that it is
expected to potentially come under attack.
Bastion hosts are often components of firewalls, or
may be ``outside'' web servers or public access
systems. Generally, a
bastion host is running some form of general purpose
operating system
(e.g., Unix, VMS, NT, etc.) rather than a ROM-based
or firmware operating system.
BAT Filename extension for a batch file.
Batch Scanning
Sequential scanning of multiple originals using
previously defined, unique settings for each.
Baud A unit of measurement that denotes number of bits that
can be transmitted per second. For example, if a modem is
rated at 9600 baud it is capable of transmitting
data at a rate of 9600 bits per second. The term was
derived from name of J.M.E. Baudot, a French pioneer in
field of printing telegraphy.
Batch Scanning Sequential scanning of multiple originals using
previously defined, unique settings for each.
BBS Bulletin Board Service. A non commercial dial-up service
usually run by a user group or software company. By
dialing up a BBS with your modem, you can exchange
messages with other users, and upload or download
software.
BGI Binary Gateway Interface. Provides a method of running a
program from a Web server. Similar to a Common Gateway
Interface (CGI). The BGI uses a binary DLL
which is loaded into memory when server starts. While
more efficient han a CGI, BGI must be compiled and is not
easily portable to other environments.
Bilevel A type of image containing only black and white pixels.
Binary A numbering system with only two values: 0 (zero) and 1
(one).
Binary File A file that contains more than plain text (i.e., photos,
sounds, spreadsheet, etc.) In contrast to an ASCII file
which only contains plain text.
Binary Number System
A counting system used in computers consisting of only
1's and 0's (zeros).
BinHex A file conversion format that converts binary files to
ASCII test files.
BIOS Basic Input-Output System. Part of computer's operating
system that is built into machine, rather than read from
a disk drive at startup.
bit A unit of measurement that represents one figure or
character of data. A bit is smallest unit of storage in a
computer. Since computers actually read 0s and 1s, each
is measured as a bit. The letter A consists of 8 bits
which amounts to one byte. Bits are often used to measure
capability of a microprocessor to process data, such as
16-bit or 32-bit.
Bit Depth The number of bits used to represent each pixel in an
image, determining its color or tonal range.
Bit-map Generally used to describe an illustration or font file
as being created by a predefined number of pixels. Also
see Object-oriented.
BITNET An academic computer network that provides interactive
electronic mail and file transfer services, using a
store-and-forward protocol, based on IBM Network Job
Entry protocols. BITNET-II encapsulates BITNET protocol
within IP packets and depends on Internet to route them.
There are three main constituents of
network: BITNET in United States and Mexico, NETNORTH in
Canada, and EARN in Europe. There are also AsiaNet, in
Japan, and connections in South
America. See CREN.
Black Point A movable reference point that defines darkest area in
an image, causing all other areas to be adjusted
accordingly.
Booting Starting up a computer via power switch, which loads
system software into memory. Restarting computer via a
keystroke combination is called rebooting or a
warm boot.
Bridge A dedicated computer used to connect two different
networks. It uses data link layer address (i.e., ethernet
physical addresses) to determine if packets should be
passed between networks.
Broadband System
A broadband system is capable of transmitting many
different signals at same time without interfering with
one another. For local area networks, a broadband
system is one that handles multiple channels of local
area network signals distributed over Cable Television
(CATV) hardware.
Broadcast A packet whose special address results in its being heard
by all hosts on a computer network.
Broadband System A broadband system is capable of transmitting many
different signals at same time without interfering with
one another. For local area networks, a broadband
system is one that handles multiple channels of local
area network signals distributed over Cable Television
(CATV) hardware.
Browser A program that enables you to access information on
Internet through World Wide Web.
bps Bits Per Second is unit used for measuring line speed,
number of information units transmitted per second.
BSD Berkeley Software Distribution. Implementation of UNIX
operating system and its utilities developed and
distributed by University of California at Berkeley. BSD
is usually preceded by version number of distribution,
e.g., 4.3 BSD is version 4.3 of Berkeley UNIX
distribution. Many Internet hosts run BSD software, and
it is ancestor of many commercial UNIX implementations.
Bug A mistake, or unexpected occurrence, in a piece of
software or in a piece of hardware.
Byte The amount of memory needed to store one character such
as a letter or a number. Equal to 8 bits of digital
information. The standard measurement unit of a file
size.
Cache An area of RAM reserved for data recently read from disk,
which allows processor to quickly retrieve it if it's
needed again.
Caching A process in which frequently accessed data is kept on
hand, rather than constantly being from place where it is
stored.
Case-dependent Software differentiation between upper and lower case
characters. Also referred to as case sensitive.
CCD Charge-coupled device. An integrated, micro-electrical
light sensing device built into some image capturing
devices.
CD-ROM Compact Disk, Read-Only Memory. A type of storage device
that looks just like an audio CD and stores as much data
as a large hard disk (600MB), making it a popular
means of distributing fonts, photos, electronic
encyclopedias, games, and multimedia offerings. As name
indicates, however, you can't save or change files on a
CD-ROM, only read them. Pronounced see-dee rom.
CGI Common Gateway Interface. A method of running an
executable script or program from a Web server. When a
client requests a URL pointing to a CGI, program is
run and results are returned to client. This enables
dynamic web pages and ability to do database queries and
other complex operations across web
Challenge/Response An authentication technique whereby a server sends an
unpredictable challenge to the user,
who computes a response using some form of authentication
token.
Chroot A technique under Unix whereby a process is
permanently restricted to
an isolated subset of the filesystem.
CIE The "Commission Internationale de l'Eclairage". An
organization that has established a number of widely-used
color definitions.
Circuit-switched A type of network connection which establishes a
continuous electrical connection between calling and
called users for their exclusive use until connection is
released. Ericsson PBX is a circuit-switched network.
Clickable Image Any image that has instructions embedded in it so that
clicking on it initiates some kind of action or result.
On a web page, a clickable image is any image that has a
URL
embedded in it.
Client/server relationship
A client application is one that resides on a user's
computer, but sends requests to a remote system to
execute a designated procedure using arguments supplied
by
user. The computer that initiates request is client and
computer responding to request is server. Many network
services follow a client and server
protocol.
Clipboard An area used to temporarily store cut or copied
information. The Clipboard can store text, graphics,
objects, and other data. The Clipboard contents are
erased when
new information is placed on Clipboard or when computer
is shut down.
Clipping The conversion of all tones lighter than a specified grey
level to white, or darker than a specified grey level to
black, causing loss of detail. This also applies to
individual
channels in a color image.
CMS Color management system. This ensures color uniformity
across input and output devices so that final printed
results match originals. The characteristics or profiles
of
devices are normally established by reference to standard
color targets.
CMYK Cyan, magenta, yellow, and black are base colors used in
printing processes. CMY are primary colorants of
subtractive color model.
Colorimeter A light-sensitive device for measuring colors by
filtering their red, green, and blue components, as in
human eye. See also spectrophoto-meter.
Color Cast An overall color imbalance in an image, as if viewed
through a colored filter.
COM1, COM2, etc. Most serial ports and internal modems on DOS/WIN PCs can
be configured to either COM1 or COM2 in order to
accommodate situation where both may exist. The
DOS MODE command is used to change output direction to
such serial devices as modems.
Compression The reduction in size of an image file. See also lossy
and non-lossy.
Computer Search Service
Computer Search Service (CSS), a fee-based service,
offers access to more than 500 databases, primarily in
sciences and social sciences, from which Library
can create customized bibliographies.
Configuration 1. The components that make up a computer system (which
model and what peripherals). 2. The physical arrangement
of those components (what's placed and where).
3. The software settings that enable two computer
components to talk to each other (as in configuring
communications software to work with a modem).
Contone (CT) An abbreviation for continuous tone. A color or greyscale
image format capable of illustrating continuously varying
tonal ranges, as opposed to line art.
Cookies
A file sent to a web browser by a web server that is used
to record once's activities.
Cookies A file sent to a web browser by a web server that is used
to record once's activities.
Coprocessor A chip designed specifically to handle a particular task,
such as math calculations or displaying graphics
on-screen. A coprocessor is faster at its specialized
function
than main processor is, and it relieves processor of
some work. A coprocessor can reside on motherboard or be
part of an expansion card, as with an
accelerator.
Coaxial Cable A type of cable that contains two conductors. The center
conductor is surrounded by a layer of insulation, which
is then wrapped by a braided-metal conductor and an
outer layer of insulation.
CPU Central Processing Unit; brains of computer. The CPU
interprets and executes actual computing tasks.
Crash A problem (often caused by a bug) that causes a program,
or entire operating system, to unexpectedly stop working.
CREN Corporation for Research and Educational Networking. This
organization was formed in October 1989, when BITNET and
CSNET (Computer + Science NETwork)
were combined under one administrative authority. CSNET
is no longer operational, but CREN still runs BITNET. See
BITNET.
Cross-platform Refers to software (or anything else) that will work on
more that one platform (type of computer).
Cryptographic Checksum
A one-way function applied to a file to produce a
unique ``fingerprint'' of the file for later reference.
Checksum systems are a primary means
of detecting filesystem tampering on Unix.
CSUNET California State University Network. A packet-switched
network that connects 22 campuses of CSU system.
Cursor The representation of mouse on screen. It may take many
different shapes. Example: I-beam, arrow pointer, and
hand.
Cyberspace A term used to refer to electronic universe of
information available through Internet.
D or Return to Quick Index
Data Driven Attack A form of attack in which the attack is encoded in
innocuous-seeming data which is executed
by a user or other software to implement an attack.
In the case of firewalls, a data driven attack
is a concern since it may get through the firewall
in data form and launch an attack against a system
behind the firewall.
DAT Digital Audio Tape. The most common type of tape backup.
Daughterboard A board that attaches to (rides piggyback on) another
board, such as motherboard or an expansion card. For
example, you can often add a daughtercard containing
additional memory to an accelerator card.
Database A file created by a database manager that contains a
collection of information organized into records, each of
which contains labeled categories (called fields).
DCS Desktop color separation. An image format consisting of
four separate CMYK PostScript files at full resolution,
together with a fifth EPS master for placement in
documents.
DDN Defense Data Network. A global communications network
serving US Department of Defense composed of MILNET,
other portions of Internet, and classified
networks which are not part of Internet. The DDN is used
to connect military installations and is managed by
Defense Information Systems Agency (DISA).
DEC Digital Equipment Corporation.
Decompression The expansion of compressed image files. See also lossy
and non-lossy.
Dedicated line A telephone or data line that is always available. For
example, a leased telephone line can be dedicated for
computer data communications. This line is not used by
other
computers or individuals, is available 24 hours a day,
and is never disconnected.
Default Route A routing table entry which is used to direct packets
addressed to networks not explicitly listed in routing
table.
Defense in Depth The security approach whereby each system on the
network is secured tothe greatest possible degree.
May be used in conjunction with firewalls.
denial of service someone make your network or firewall
crashing it, jamming it, or flooding it.
TCP/IP's UDP echo service is trivially
abused to get two servers to flood a
network segment with echo packets.
You should consider commenting out unused
entries in /etc/inetd.conf of Unix hosts,
adding no ip small-servers to
Cisco routers, or the equivalent for your components.
Denial of service - nearly impossible
to counter. hacker sends a
request to server to connect to it. When the
server responds with an acknowledgement and tries to
establish a session, it cannot find the system that
made the request. By inundating a server with these
unanswerable session requests, a hacker causes the
server to slow to a crawl or eventually crash
Densitometer A measuring instrument that registers density of
transparent or reflective materials. Colors are read as
tonal information. See also colorimeter and
spectrophotometer.
Density Density is a brightness control to lighten or darken a
printout to more closely reflect its screen appearance
and to compensate for deficiencies in toner or paper
quality.
Descreening Removal of halftone dot patterns during or after scanning
printed matter by defocusing image. This avoids moire
patterning and color shifts during subsequent
halftone reprinting.
Dialog box A window that displays additional options or questions
when a command is chosen.
Dial-up line A communication connection from your computer to a host
computer over standard phone lines. Unlike a dedicated
line, you must dial host computer in order to
establish a connection. Dial-up line is currently most
popular form of Net connection for home user.
Dichroic Mirror A special type of interference filter, which reflects a
specific part of spectrum, whilst transmitting rest. Used
in scanners to split a beam of light into RGB
components.
Digital Data or voltages consisting of discrete steps or levels,
as opposed to continuously variable analog data.
Digitizers
A machine which converts analog data into digital data on
a computer (such as a scanner digitizing pictures or
text).
Digitizers A machine which converts analog data into digital data on
a computer (such as a scanner digitizing pictures or
text).
DIP switches Dual Interface Poll switches allow for either an ON or
OFF setting with any number of circuits. DIP switches
commonly allow you to change configuration of a
circuit board to suit your particular computer.
Direct connection A permanent communication connection between your
computer system (either a single CPU or a LAN) and
Internet. This is also called a leased line connection
because you are leasing telephone connection from phone
company. A direct connection is in contrast to a SLIP/PPP
or dial-up connection.
Direct-To-Plate Direct exposure of image data onto printing plates,
without intermediate use of film.
Direct-To-Press Elimination of intermediate film and printing plates by
direct transfer of image data to printing cylinders in
press.
Directory A system that your computer uses to organize files on
basis of specific information.
Disk Defragmenter
Arranges blocks of information for a file into adjacent
blocks on your hard drive, which may significantly
improve file access times.
Disk Defragmenter Arranges blocks of information for a file into adjacent
blocks on your hard drive, which may significantly
improve file access times.
Dmax The point of maximum density in an image or an original.
Dmin The point of minimum density in an image or an original.
DNS Domain Name System. A general purpose distributed,
replicated, data query service. Its principal use is
lookup of host IP addresses based on host names. The host
names are also known as domain names. Some important
domains are: .COM (commercial), .EDU (educational), .NET
(network operations), .GOV (U.S. government),
and .MIL (U.S. military). Most countries also have a
domain. For example, .US (United States), .UK (United
Kingdom), .AU (Australia).
Dmax The point of maximum density in an image or an original.
Dmin
The point of minimum density in an image or an original.
DNS Domain Name System. A general purpose distributed,
replicated, data query service. Its principal use is
lookup of host IP addresses based on host names. The host
names are also known as domain names. Some important
domains are: .COM (commercial), .EDU (educational), .NET
(network operations), .GOV (U.S. government),
and .MIL (U.S. military). Most countries also have a
domain. For example, .US (United States), .UK (United
Kingdom), .AU (Australia).
DNS spoofing Assuming the DNS name of another system by either
corrupting the name
service cache of a victim system, or by compromising
a domain name server for a valid domain.
Domain names Because it is hard to remember the
string of numbers that make up an IP address, and
because IP addresses sometimes need to change, all
servers on the Internet also have human-readable
names, called domain names. For example, it is easier
for most of us to remember www.howstuffworks.com than
it is to remember 216.27.61.137. A company might
block all access to certain domain names, or allow
access only to specific domain names.
Domain Name Servers, DNS, are an incredibly important but
completely hidden part of the Internet,
http://www.howstuffworks.com
Contains domain name howstuffworks.com.
So does this email address:
brain@howstuffworks.com
Domain name servers translate domain names
to IP addresses.
There are billions of IP addresses currently in use,
and most machines have a human readable name as well.
There are many billions of requests made from domain
name servers every day.
Domain Names Work If we had to remember the IP addresses of all of the web
sites we visit every day, we would all go nuts. Human
beings just are not that good at remembering
strings of numbers. We are good at remembering words,
however, and that is where domain names come in. You
probably have hundreds of domain names
stored in your head. For example:
www.howstuffworks.com -- a typical name
www.yahoo.com -- the world's best-known name
www.mit.edu -- a popular EDU name
encarta.msn.com --web server that does not start with www
www.bbc.co.uk -- a name using 4 parts rather than 3
ftp.microsoft.com -- an ftp server rather than a web
server
The .COM, .EDU and .UK portions of these example domain
names are called the top-level domain or first-level
domain. There are several hundred
top-level domain names, including COM, EDU, GOV, MIL, NET,
ORG and INT, as well as unique two-letter combinations for
every country.
Distributing Domain Names
Because all of the names in a given domain need to be
unique, there needs to be a single entity that controls
the list and makes sure no duplicates arise. For example,
the COM domain cannot contain any duplicate names,
a company called Network Solutions in charge of this
list.When you register a domain name, goes through one of
several dozen registrars who work with Network Solutions
to add names to list. Network Solutions, in turn,
keeps a central database known as whois database that
contains information about owner and name servers for
each domain. If you go to the whois form you can find
information about any domain currently in existence.
Microsoft wants to maintain its own domain name
server for the microsoft.com domain. Similarly, Great
Britain probably wants to administrate the uk top-level
domain, Australia wants to administrate the au domain,
For this reason, DNS system is a distributed database.
Microsoft is completely responsible for dealing with the
name server for microsoft.com -- it maintains the machines
that implement its part of the DNS system, and Microsoft
can change the database for its domain whenever it wants
to because Microsoft owns its domain name servers.
Every domain has a domain name server somewhere that
handles its requests, and there is a person maintaining
the records in that DNS. This is one of the most amazing
parts of
the DNS system -- it is completely distributed throughout
the world on millions of machines administered by millions
of people, yet it behaves like a single, integrated
database!
Domain Name System is a distributed database,
are central name servers at core of system
Someone maintain these central name servers to
avoid conflicts and duplication.
In 1993, U.S. Department of Commerce, in conjunction
with several public and private entities,created InterNIC
to maintain a central database
that contains all the registered domain names and
associated IP addresses in U.S.
(other countries maintain their own NICs
(Network Information Centers)
Network Solutions, a member of InterNIC, was
chosen to administer and maintain growing number of
Internet domain names and IP addresses.
This central database is copied to Top Level
Domain (TLD) servers around the world
and creates primary routing tables
used by every computer that connects to the Internet.
Until recently, Network Solutions was only company
provided domain names.
However, to ensure that Network Solutions did not become
monopoly, U.S. government decided that other
companies should also be allowed to sell domain names.
While these other companies (known as registrars)
provide domain names and maintain DNS servers,
Network Solutions still maintains central database
to ensure that there are no duplicates.
In U.S., you pay Network Solutions an annual fee
to maintain your domain name in central name server.
Domain Name Server A computer that converts host names, such as
rohan.sdsu.edu to its corresponding IP Address, such as
191.130.1.10. An SDSU computer provides this service any
time
mail is sent or received and permits users to use TELNET
and FTP between SDSU and other sites.
DOS Disk Operating System. The operating system used on IBM
personal computers and compatible machines.
Dotted Decimal Notation
The convention for writing 32-bit IP Addresses as a set
of four 8-bit numbers written in base 10 with periods
separating them.
Down-Sampling The reduction in resolution of an image, necessitating a
loss in detail.
Download To retrieve a file from another computer using a modem.
dpi Dots Per Inch. A measure of resolution of a printer,
scanner, or monitor. It refers to number of dots in a
one-inch line. The more dots per inch, higher
resolution.
Driver A piece of software that tells computer how to operate
an external device, such as a printer, hard disk, CD-ROM
drive, or scanner. For instance, you can't print
unless you have a printer driver. Hard disk drivers are
invisible files that are loaded into memory when you
start computer, while scanner drivers are usually
plug-ins
accessed from within a particular application.
Drum Scanner Early drum scanners separated scans into CMYK data,
recording these directly onto film held on a second
rotating drum.
DTP Desktop Publishing.
Dual Homed Gateway a system that has two or more network
interfaces, eachconnected to a different network. In
firewall configurations, acts to block or
filter traffic trying to pass between networks.
Dump Back-up of data.
Duplex (Full, Half) Full duplex is data is flowing in both directions at
same time. When Remote echo is ON communication is
occurring in full duplex. Half Duplex has data moving in
only
one direction at a time (Local echo is ON).
DXF Drawing Interchange Format used for Macintosh graphic
files. The standard file-exchange format for 3-D and CAD
programs.
Dye Sublimation A printing process using small heating elements to
evaporate pigments from a carrier film, depositing these
smoothly onto a substrate.
EARN European Academic Research Network.
Echo (Local, Remote)
Local echo ON causes all transmitted data to be sent to
screen of sending computer. Remote echo ON causes
everything that remote computer (the one you
are communicating with) transmits to be duplicated on
your computer's screen. See Duplex.
Echo (Local, Remote) Local echo ON causes all transmitted data to be sent to
screen of sending computer. Remote echo ON causes
everything that remote computer (the one you
are communicating with) transmits to be duplicated on
your computer's screen. See Duplex.
EBCDIC Extended Binary-Coded Decimal Interchange Code. A
standard character-to-number encoding used primarily by
IBM computer systems. See ASCII.
E-mail Electronic Mail. Private messages sent between users on
different computers, either over a network or via a modem
connection to an on-line service or BBS.
E-mail bombs An e-mail bomb is usually a personal
attack. Someone sends you the same e-mail hundreds or
thousands of times until your e-mail system cannot
accept any more messages.
Encoding File transfer formatting that enables encrypted,
compressed or binary files to be transferred without
corruption or loss of data.
Encryption A way of coding information in a file or e-mail message
so that if it is intercepted by a third party as it
travels over a network it cannot be read.
Encrypting Router see Tunneling Router and Virtual Network Perimeter.
EPS Encapsulated PostScript. An EPS file usually has two
parts: a PostScript (text) description that tells a
PostScript printer how to output resolution-independent
image,
and (optionally) a bit-mapped PICT image for on-screen
previews. (EPS files without a PICT preview is usually
displayed as a gray rectangle.) EPS files generally
can't be edited, even by program that created them
(Illustrator files are exceptions).
EPS 5
Another term used for DCS.
ERIC An index to educational journal articles and documents
collected by national clearing houses for educational
information. It provides summaries of articles and
documents, and contains citations back to 1966.
Ethernet An IEEE 802.3 standard data link layer which can operate
over several different media including fiber optic,
coaxial cable and twisted-pair cable. This 10
million-bit-per-second networking scheme is widely used
on campus because it can network a wide variety of
computers; it is not proprietary; and components are
widely available from many commercial sources.
Executable File
Refers to a file that is a program. Executables in DOS
and Windows usually have an .exe or a .com extension. In
UNIX and Macintosh environments, executable files
can have any name.
Executable File Refers to a file that is a program. Executables in DOS
and Windows usually have an .exe or a .com extension. In
UNIX and Macintosh environments, executable files
can have any name.
External viewer Program used for presenting graphics, audio and movies
while browsing World Wide Web pages via a Web client
program. Helper applications is another term for these
external programs.
F or Return to Quick Index
FAQ Frequently Asked Questions. A document that covers a
topic of general concern to many users. FAQs are a good
way for new users to get information on various
aspects of Internet.
FDDI Fiber Distributed Data Interface. An emerging standard
for network technology based on fiber optics that has
been established by American National Standards
Institute (ANSI). FDDI specifies a 100-million bit per
second data rate.
File A collection of information on a disk, usually a document
or a program, that's lumped together and called by one
name.
File Permissions When you place files on a UNIX system you can assign
files various levels of permission, specifying who can
access them, and what type of access they can have.
File Server A computer that shares its resources, such as printers
and files, with other computers on network. An example of
this is a Novell NetWare Server which shares its
disk space with a workstation that does not have a disk
drive of its own.
Film Recorder Used in reference to color transparency recording
devices, and sometimes also to imagesetters.
Filter A piece of software that an application uses for
file-format conversion or special effects. PageMaker, for
example, has a filter that lets it import Microsoft Word
files,
while Photoshop has dozens of filters for special effects
(such as image blurring). Filters can be part of main
application or external programs called plug-ins.
Finger A program that displays information about someone on
internet.
firewall is simply a program or hardware device that
filters the information coming through the Internet
connection into your private network or computer system.
If an incoming packet of information is flagged by the
filters, it is not allowed through.
Firewalls use one or more of three methods to control
traffic flowing in and out of the network:
firewall will sniff (search through) each packet
of information for an exact match of the text listed
in the filter. For example, could instruct the
firewall to block any packet with the word "X-rated"
Firewall enforces a boundary between two or more networks.
Firewall A mechanism that isolates a network from rest of
Internet, permitting only specific traffic to pass in and
out.
Flaming/Flame War Reacting to someone's newsgroup posting or e-mail in a
hostile manner by publicly chastising person or
bombarding person with nasty e-mail.
Flatbed Scanner
Any scanning device that incorporates a flat transparent
plate, on which original images are placed for scanning.
The scanning process is linear rather than rotational.
Floating-point Processor
A special chip that handles sophisticated calculations,
such as those used in spreadsheets, CAD, and scientific
programs.
Flatbed Scanner Any scanning device that incorporates a flat transparent
plate, on which original images are placed for scanning.
The scanning process is linear rather than rotational.
Floating-point Processor
A special chip that handles sophisticated calculations,
such as those used in spreadsheets, CAD, and scientific
programs.
Folder An object that can hold other objects, such as other
folders and files.
Font The software that creates a typeface on a computer
screen.
Format To initialize a disk to prepare it for use. The disk is
checked for errors and organized so that data can be
recorded and retrieved. Formatting a used disk erases any
previously stored information.
FPO For Position Only. A low resolution image placed in a
document to indicate where final version is to be
positioned.
Fragmentation A condition where parts of a file are stored in different
locations on a disk. When a file is fragmented, drive's
read/write head has to jump from place to place to read
data; if many files are fragmented, it can slow drive's
performance.
Frame-grabbing System
A combination of hardware and software, designed to
capture individual frames from video clips for further
digital manipulation, or consecutive replay on computer
platforms.
FTP (File Transfer Protocol) - used to download
and upload files
FTP File Transfer Protocol. The Internet standard high-level
protocol for transferring files from one computer to
another across network.
FTP site A computer which stores files that can be retrieved using
FTP. FTP sites which allow anyone to retrieve files
(without having an account on that computer) are known
as Anonymous FTP sites.
G or Return to Quick Index
Gamma Correction The correction of tonal ranges in an image, normally by
adjustment of tone curves.
Gamut The limited range of colors provided by a specific input
device, output device or pigment set.
Gang Scanning Sequential scanning of multiple originals using same
previously defined exposure setting for each.
Gateway A special-purpose dedicated computer that attaches to two
or more disparate networks and converts data packets from
one form to another.
GB Gigabyte. A unit of data storage size which represents
10^9 (one billion) characters of information.
Gb Gigabit. 10^9 bits of information (usually used to
express a data transfer rate; as in, 1 Gigabit/second =
1Gbps).
GCG (Grey Component Replacement)
A technique for replacing all neutral tones of an image
with an appropriate amount of black.
GIF Graphic Interchange Format (pronounced jiff). A file
compression format developed by CompuServe for
transferring graphic files to and from on-line services.
Gigabyte 1,024 megabytes, or 1,048,576 kilobytes of digital data.
gopher A consistent user interface and gateway into many on-line
white pages and other address databases.
Graphical User Interface (GUI)
The graphical visual representation of working
environment that presents elements of your computer as
objects on a desktop.
Grey Balance The balance between CMY colorants required to produce
neutral greys without a color cast.
Grey Levels Discrete tonal steps in a continuous tone image, inherent
to digital data. Most CT images will contain 256 grey
levels per color.
Greyscale A continuous tone image comprising black, white, and grey
data only.
H or Return to Quick Index
Hacker Slang term for a technically sophisticated computer user
who enjoys exploring computer systems and programs,
sometimes to point of obsession.
Halftone A simulation of continuous tones by use of black or
overlapping process color dots of varying size or
position.
Halftoning Factor See quality factor.
Halo A light line around object edges in an image, produced by
USM (sharpening) technique.
Handle Unique character string identifier assigned to each entry
in NIC WHOIS database.
Handshaking The process computers and modems go through in order to
establish a connection and agree on speed and protocols
for data transmission.
Hayes Compatible A modem is considered Hayes Compatible if it supports
Hayes command set (a language used to communicate with
and control a modem).
Header The portion of a packet, preceding actual data,
containing source and destination addresses, error
checking and other fields. A header is also part of an
electronic
mail message that precedes body of a message and
contains, among other things, message originator, date
and time.
High Key A light image that is intentionally lacking in shadow
detail.
Highlight The lightest tones in an image. A spectral highlight is a
bright, reflected light source.
Histogram A chart displaying tonal ranges present in an image as a
series of vertical bars.
Home Page The document that is displayed when you first open a web
client program. Also, commonly used to refer to first
document you come to in a collection of documents
on a Web site.
Host The main computer system to which users are connected.
Hostname
Name which officially identifies each computer attached
to Internet.
Host-based Security technique of securing an individual system from attack.
is operating system and version dependent.
otlist A file containing lists of Internet Web pages, enabling
you to easily access your favorite Web pages.
HP Hewlett Packard.
HTML HyperText Markup Language. A system for tagging various
parts of a Web document that tells Web client programs
how to display document's text, links,
graphics and attached media.
HTTP (Hyper Text Transfer Protocol) - used for
Web pages
Hue The color of an object perceived by eye due to fact
that a single or pair of RGB primary colors predominates.
Hypermedia Describes hypertext in which various types of data can be
stored - sound, images, video and so on - as regular
text.
Hypertext A text-linking strategy that lets you jump between
related information in a document by clicking on a button
or highlighted word. On-line help systems often use
hypertext links, as do some programs designed for
electronic distribution of documents.
I/O Input/Output.
I-beam The blinking vertical line that shows point at which
text or graphics will be inserted.
IBM International Business Machines Corporation.
ICMP (Internet Control Message Protocol) - used
by a router to exchange the information with
other routers
ICMP redirects and redirect bombs?
An ICMP Redirect tells recipient system
to over-ride something in its routing table.
legitimately used by routers to tell hosts that
host is sending it to wrong router.
wrong router sends host back
an ICMP Redirect packet that tells host
what correct route should be.
If forge ICMP Redirect packets,
and if target host pays attention to them,
can alter routing tables on host
possibly subvert security of host
causing traffic to flow a path
ICMP Redirects also may be employed
for denial of service attacks,
where a host is sent a route that loses it connectivity,
or sent ICMP Network Unreachable packet
telling it can no longer access a particular network.
Many firewall builders screen ICMP traffic
from their network, since it
limits ability of outsiders to ping hosts,
or modify their routingtables.
Before you decide to completely block ICMP,
should be aware of how TCP protocol does
``Path MTU Discovery'',
to make certain that you don't
break connectivity to other sites.
Icon A graphic symbol, usually representing a file, folder,
disk or tool.
Image Map A graphic divided into regions or "hotspots". When a
particular region is clicked, it calls up a web page that
has been associated with that particular region.
Imagesetter A device used to record digital data (images and text)
onto monochrome film or offset litho printing plates by
means of a single or multiple intermittent light beams.
Color
separated data is recorded as a series of slightly
overlapping spots to produce either solid areas of
line-art or halftone dots for printing continuous tones.
Import To bring data into a document from another document,
often generated by a different application.
Inactive Window A window that is open but is not top window.
Infopath Internet gopher for University of California at San
Diego.
Information Technology
Includes matters concerned with furtherance of computer
science and technology, design, development, installation
and implementation of information systems and
applications.
Initializing (formatting)
Setting up a disk (any kind) to receive information. When
a disk is initialized (formatted), its magnetic media is
divided into tracks and sectors, and structure files that
your
computer uses to keep track of data are created.
Inline images Graphics that are contained within a document's textual
information. In a Web document, these graphics can either
be loaded automatically when page is accessed
or loaded manually by clicking on image's icon.
Insider Attack An attack originating from inside a protected network.
Installer A utility that copies system software or an application
from floppy disks or a CD-ROM to your hard disk. An
Installer may also decompress new files, remove
obsolete files, place extensions and control panels in
their proper folders, and/or create new folders.
Interface The way a computer interacts with a user or a peripheral.
Internet
The Internet (note capital I) is largest internet in
world. It is a three level hierarchy composed of backbone
networks (e.g., NSFNET, MILNET), mid-level
networks, and stub networks. The Internet is a
multiprotocol internet.
Interpolation In image manipulation context, this is increase of
image resolution by addition of new pixels throughout
image, colors of which are based on
neighboring pixels
Internet domain names registered and maintained?
Since its beginning in 1969, the Internet has grown from
four host computer systems to tens of millions. ,
just because nobody owns the Internet, it doesn't mean it
is not monitored and maintained in different ways.
Internet Society, a non-profit
group established in 1992, oversees the formation of
policies and protocols that define
how we use and interact with Internet.
When Internet was in its infancy, only connections
by providing IP (Internet Protocol) address
typical IP address might be 216.27.22.162. T
first solution to was text file maintained by
Network Information Center
that mapped names to IP addresses. Soon
this text file became so large
it was too cumbersome to manage.
1983,University of Wisconsin created Domain Name System
DNS), which maps text names to IP addresses.
only need to remember www.howstuffworks.com,
instead of 216.27.22.162.
.
Interrupt A brief interruption of computer's activity so that an
urgent task can be performed.
Intrusion Detection Detection of break-ins or break-in attempts
either manually or via software expert systems
that operate on logs or other information
available on the network.
IP (Internet Protocol) - the main delivery
system for information over the Internet
IP Internet Protocol is standard that allows dissimilar
hosts to connect to each other through Internet. This
protocol defines IP datagram as basic unit of
information sent over Internet. The IP datagram consists
of an IP header followed by a message.
IP addresses Each machine on the Internet is
assigned a unique address called an IP address. IP
addresses are 32-bit numbers, normally expressed as
four "octets" in a "dotted decimal number." A typical
IP address looks like this: 216.27.61.137. For
example, if a certain IP address outside the company
is reading too many files from a server, the firewall
can block all traffic to or from that IP address.
IP Addresses Work each machine is assigned a unique address called
an IP Address.
IP stands for Internet protocol, and these addresses are
32-bit numbers normally expressed as 4 "octets" in a
"dotted decimal number". A typical IP address looks like
this:
216.27.61.137
The four numbers in an IP address are called octets
because they can have values between 0 and 255 (28
possibilities per octet).
Every machine on the Internet has a unique IP address.
A server has static IP address that does not change often.
A home machine that is dialing up through a modem often
has an IP address that is assigned by the ISP when you
dial in. That IP address is unique for your session but
may be different the next time you dial in.
can view your current IP address with command
WINIPCFG.EXE. On a
UNIX machine type nslookup along with a machine
name (like www.howstuffworks.com -- e.g. "nslookup
www.howstuffworks.com") to display the IP address of the
machine (use command hostname to learn name of your
machine). [For more information on IP addresses see IANA]
As far as the Internet's machines are concerned, an IP
address is all that you need to talk to a server. For
example, in your browser you can type the URL
http://216.27.61.137 and
you will arrive at the machine that contains the web
server for How Stuff Works. Domain names are strictly a
human convenience.
IP Address Network addresses are usually of two types: (1) physical
or hardware address of a network interface card; for
Ethernet this 48-bit address might be
0260.8C00.7666. The hardware address is used to forward
packets within a physical network. (2) The logical or IP
Address is used to facilitate moving data between
physical networks and is made up of a network number, a
subnetwork number, and a host number. All Internet
addresses at SDSU have a network number of 130.191, a
subnet number in range of 1-254, and a host number in
range of 1-254.
IP Datagram The basic unit of information passed across Internet. An
IP Datagram is to Internet as a hardware packet is to a
physical network. It contains a source and
destination address along with data. Large messages are
broken down into a sequence of IP Datagrams.
IP Spoofing An attack whereby a system attempts to illicitly
impersonate another system using its IP network address.
IPSplicing/Hijacking An attack whereby an active, established, session is
intercepted and co-opted by the attacker. IP Splicing
attacks may occur after an authentication has been made,
permitting the attacker to assume the
role of an already authorized user. Primary protections
against IP Splicing rely on encryption
at the session or network layer.
IRC Internet Relay Chat. A program that allows you to carry
on "live" conversations with people all over world by
typing messages back and forth across Internet.
ISAAC Information System for Advanced Academic Computing.
Serves as a clearinghouse for information about use of
IBM-compatible hardware and software as aids to
instruction and research in higher education. Membership
is free to all students, faculty, and staff at these
institutions.
ISO International Organization for Standardization, group
that developed OSI protocols.
ISP Internet Service Provider. A company that provides access
to Internet. A service provider can offer simple dial-up
access, SLIP/PPP access, or a dedicated line.
IT8 Industry standard color reference target used to
calibrate input and output devices.
ITV Interactive Television.
Java An object-oriented programming language to create
executable content (i.e. self-running applications) that
can be easily distributed through networks like Web.
JPEG Joint Photographic Experts Group is a graphic file format
that has a sophisticated technique for compressing
full-color bit mapped graphics, such as photographs.
K or Return to Quick Index
KB KiloByte. A unit of data storage size which represents
10^3 (one thousand) characters of information.
Kb Kilobit. 10^3 bits of information (usually used to
express a data transfer rate; as in, 1 Kilobit/second =
1Kbps = 1Kb).
Kermit An error-checking file-transfer protocol used to copy
files from one computer to another. Also name given to
public domain software distributed by Columbia
University, which supports this protocol.
Kernel Size The number of pixels sampled as a unit during image
manipulation and sharpening processes.
Keyword Specified words used in text search engines.
Kilobyte (Kb)
1,024 bytes of digital data.
L or Return to Quick Index
LAN Local Area Network. A network of directly-connected
machines (located in close proximity), providing high
speed communication over physical media such as fiber
optics, coaxial cable, or twisted pair wiring.
Laser Printer Although a number of devices employ laser technology to
print images, this normally refers to black-and-white
desktop printers, which use dry toner, xerographic
printing process.
Laserdisc A 12-inch disk that's similar to an audio CD but holds
visual images (such as high-quality movies) as well as
music. Also called a videodisc.
Links
Least Privilege Designing operational aspects of a system to operate with
a minimum
amount of system privilege. This reduces the authorization
level at
which various actions are performed and decreases the
chance that a
process or user with high privileges may be caused to
perform
unauthorized activity resulting in a security breach.
Synonymous with anchors, hotlinks and hyperlinks.
Line Art Images containing only black and white pixels. Also known
as bilevel images. The term line art is sometimes used to
describe drawings containing flat colors without
tonal variation.
LION Library Internet Online Network. A menued front-end
system at SDSU that allows access to a number of
databases such as library on-line catalogs, periodical
indexes, and Internet gophers.
LISTSERV A distribution list management package whose primary
function is to operate mailing lists. It allows groups of
computer users with a common interest to communicate
among themselves.
Local system The system you are using. Interactions between your
computer and another computer on Internet are sometimes
described using terms "local" and "remote"
systems. The local system is your computer and remote
system is other computer.
LOCIS Library of Congress catalog system. The Library of
Congress has an extensive and useful congressional
legislation system that you can use to look up bills that
are in
Congress, as well as having nearly any book ever
published in United States.
Login The account name used to access a computer system.
Logging The process of storing information about events that
occurred on the
firewall or network.
Log Retention How long audit logs are retained and maintained.
Log Processing How audit logs are processed, searched for key events, or
summarized.
Lossy Image compression that functions by removing minor tonal
and/or color variations, causing visible loss of detail
at high compression ratios.
Low Key A dark image that is intentionally lacking in highlight
detail.
LPI/LPCM Lines per inch or per centimeter. Units of measurement
for screen ruling.
Lurker Slang term for someone who regularly reads newsgroup,
BBS, or mailing list discussions, but rarely participates
in them.
Lynx A type of browser designed to work with text-only
Internet connections like dial-up UNIX shell accounts.
LZW The Lempel-Ziv-Welch image compression technique.
M or Return to Quick Index
Macros To simplify complicated procedures, many
applications allow you to create a script of commands
that the application can run. This script is known as
a macro. Hackers have taken advantage of this to
create their own macros that, depending on the
application, can destroy your data or crash your
computer.
Mail Merge The merging of database information (such as names and
addresses) with a letter template in a word processor, in
order to create personalized letters.
Mailing List A list of Email users who are members of a group. A
mailing list can be an informal group of people who share
Email with one another, or it can be a more formal
LISTSERV group which discusses a specific topic.
Mainframe A large, multi-tasking computer that is used by many
users.
Marvel Machine-Assisted Realization of Virtual Electronic
Library. The Library of Congress' gopher. It presents
information about Library of Congress such as
facilities and services, reading rooms, copyright,
services to libraries and publishers, etc., as well as
other Internet resources.
Math Coprocessor Another name for a floating-point processor.
Matrix
This often refers to a 2-dimensional array of CCD
elements.
Medium The material used to support transmission of data.
Examples include twisted-pair wire, coaxial cable,
optical fiber, or electromagnetic wave (microwave).
Megabit (Mb) Megabit. 10^6 bits of information (usually used to
express a data transfer rate; as in, 1 Megabit/second =
1Mbps).
Megabyte (MB) MegaByte. A unit of data storage size which represents
10^6 (one million) characters of information.
Megahertz (MHz) A million cycles (occurrences, alterations, pulses) per
second. Used to describe speed at which a computer's
processor (or CPU) operates.
Melvyl An on-line catalog system containing books, music scores
and recordings, audiovisual materials, maps, and computer
files from UC libraries and California State
Library. Also featured are periodicals from several
sources.
Memory In general, another word for dynamic RAM, chips where
computers store system software, programs, and data you
are currently using. Other kinds of computer
memory you may encounter are parameter RAM (PRAM), video
RAM (VRAM), and static RAM (SRAM). Most computer memory
is volatile, that is, its contents are
lost when computer shuts down.
Menu A list of commands.
Menu Bar
The horizontal bar that contains names of available
menus. The menu bar is located below title bar.
Message A collection of data that is ordered according to rules
of a given protocol suite, such that it is intelligible
to sending and receiving software.
MHz Megahertz. A million cycles (occurrences, alterations,
pulses) per second. Used to describe speed at which a
computer's processor (or CPU) operates. A 25-MHz
processor can handle 25 million operations per second.
MIDI Musical Instrument Digital Interface. A technology that
enables a computer to record and play musical
performance.
Midtone
The middle range of tones in an image.
MILNET Military Network. A network used for unclassified
military production applications. It is part of DDN and
Internet.
MIME Multi-purpose Internet Mail Extensions. A format
originally developed for attaching sounds, images and
other media files to electronic mail, but now also used
with
World Wide Web applications.
MIME mappings A list of file extensions and types of files they belong
to. When server sends an HTTP reply, it sends a
type/subtype header according to requested file's
extension.
MIME type/subtype
An HTTP header sent with a reply that determines how a
client will view or use message. The MIME type tells
general type of document, such as image or
application, and subtype tells specific type such as
GIF or ZIP.
MIPS Millions of Instructions Per Second.
Mirror site An FTP site that is created after contents of an
original FTP archive server are copied to it. Usually,
mirror sites use larger and faster systems than original,
so it's
easier to obtain material from mirror. Mirror sites are
usually updated daily, so everything on original is also
at mirrors. Tip - Always use mirror site that is
physically closest to you.
Modem A device which converts digital signals into analog
signals (and back) for transmission over telephone lines
(modulator and demodulator).
Moire A repetitive interference pattern caused by overlapping
symmetrical grids of dots or lines having differing pitch
or angle.
Monochrome Single-colored. An image or medium displaying only
black-and-white or greyscale information. Greyscale
information displayed in one color is also monochrome.
Motherboard
The heart, soul, and brains of a computer. This plastic
board resembles a miniature city, but its buildings are
actually chips for things like processing, RAM, and ROM,
and tiny roads connecting them are circuit traces. Also
called logic board. There are no fatherboards or
sonboards, but see daughterboard.
Mottling A texture similar to orange peel sometimes caused by
sharpening. It is particularly visible in flat areas such
as sky or skin.
MOV A file extension found on World Wide Web that denotes
that file is a movie or video in QuickTime format.
MPEG Moving Pictures Expert Group. MPEG is an international
standard for video compression and desktop movie
presentation. You need a special viewing application to
run
MPEG movies on your computer. MPEG II is a newer
standard for broadcast-quality video.
Multimedia Any presentation or software program that combines
several media, such as graphics, sound, video, animation,
and/or text.
Multiplex The division of a single transmission medium into
multiple logical channels supporting many apparently
simultaneous sessions.
Multitasking The capability of an operating system to handle multiple
processing tasks, apparently, at same time.
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This page last modified: November 24, 1998
Glossary of Academic Information
Technology Terms
N or Return to Quick Index
Native Software that's written specifically to run on a
particular processor. For example, a program optimized
for a 68K processor runs in native mode on a Quadra, but
it runs
in emulation mode (which is slower on a Power PC-based
Power Mac). Also, file format in which an application
normally saves it documents. The native format is
generally readable only by that application (other
programs can sometimes translate it using filters).
Navigation Tools Allows users to find their way around a website or
multimedia presentation. They can be hypertext links,
clickable buttons, icons, or image maps.
Netiquette A form of online etiquette. This term refers to an
informal code of conduct that governs what is generally
considered to be acceptable way for users to interact
with
one another online.
news A term often used to denote USENET news, a popular forum
for discussion on Internet.
newsgroup A discussion group, usually found on USENET news. Each
group devotes its discussions to a specific topic.
newsreader A software program that lets you subscribe to newsgroups
as well as read and post messages to them.
news server A machine that contains a number of USENET newsgroups.
Also referred to a NNTP server.
Netware The chief priest of network operating systems.
Network In general, a group of computers set up to communicate
with one another. Your network can be a small system
that's physically connected by cables (a LAN), or you
can connect separate networks together to form larger
networks (called WANs). The Internet, for example, is
made up of thousands of individual networks.
Network-LayerFirewall A firewall in which traffic is examined at the network
protocol packet
layer.
network firewall Generally, protect against unauthenticated
interactive logins
they can provide a single ``choke point''
where security and audit can be imposed.
NFS Network File System. A protocol developed by Sun
Microsystems which allows a computer system to access
files over a network as if they were on its local disks.
This
protocol has been incorporated in products by more than
two hundred companies, and is now a de facto Internet
standard.
NIC Network Information Center. A organization that provides
information, assistance and services to network users.
NOC Network Operations Center. A location from which
operation of a network or internet is monitored.
Additionally, this center usually serves as a
clearinghouse for
connectivity problems and efforts to resolve those
problems.
Node A computer that is attached to a network; sometimes
called a host.
Noise In scanning context, this refers to random, incorrectly
read pixel values, normally due to electrical
interference or device instability.
Non-lossy Image compression without loss of quality.
NSFNET National Science Foundation Network. The NSFNET is a high
speed network of networks which is hierarchical in
nature. At highest level is a backbone network
which spans continental United States. Attached to that
are mid-level networks and attached to mid-levels are
campus and local networks. NSFNET also has
connections out of U.S. to Canada, Mexico, Europe, and
Pacific Rim. The NSFNET is part of Internet.
O or Return to Quick Index
Object-oriented
Generally used to describe an illustration or font file
as being created by mathematical equations. Also see
Bit-map.
OCR Optical Character Recognition. A technology that lets you
scan a printed page (with a scanner) and convert it into
text document that you can edit in a word processor.
Offset lithography A high-volume, ink-based printing process, in which ink
adhering to image areas of a lithographic plate is
transferred (offset) to a blanket cylinder before being
applied
to paper or other substrate.
Network Operations Center. A location from which
On-line Actively connected to other computers or devices. You're
on-line when you've logged on to a network, BBS, or
on-line service. A device such as a printer is on-line
when it's turned on and accessible to a computer. If
you're not on-line then you're off-line.
On-line Service A commercial service that (for a price) provides goodies
such as e-mail, discussion forums, tech support, software
libraries, news, weather reports, stock prices, plane
reservations, even electronic shopping malls. To access
one, you need a modem. Popular on-line services include
America Online, CompuServe, and Prodigy.
Operating System Software that supervises and controls tasks on a
computer.
Operating system bugs Like applications, some
operating systems have backdoors. Others provide
remote access with insufficient security controls or
have bugs that an experienced hacker can take
advantage of
Optical Resolution In scanning context, this refers to number of truly
separate readings taken from an original within a given
distance, as opposed to subsequent increase in
resolution (but not detail) created by software
interpolation.
Optical Video Disc Compact discs which use lights to read information.
OSI Open Systems Interconnection, a set of standard protocol
grouped into seven layers: physical, data link, network,
transport, session, presentation, and application
layers.
P or Return to Quick Index
PAC Public Access Catalog. The SDSU University Library's
on-line catalog which lists books held here and journals
subscribed to (but not their contents. It also
provides information on circulation status, books and
journals ordered but not yet received, receipt of journal
issues, and more.
Packet The unit of data sent across a packet switching network.
While some Internet literature use term to refer
specifically to data sent across a physical network,
other
literature views Internet as a packet switching network
and describes IP Datagrams as packets.
Packet filtering Packets (small chunks of data) are
analyzed against a set of filters. Packets that make
it through the filters are sent to the requesting
system and all others are discarded.
Packet-switching Data transmission process, utilizing addressed packets,
whereby a channel is occupied only for duration of packet
transmission. SDSUnet is a are packet-switching network.
Paint The oldest and most limited Macintosh graphic file
format, holding only black-and-white bit maps at 72 dpi.
Paint files (file type PNTG) are limited to 8 by 10
inches.
Parallel Cable/Parallel Port
A cable used to connect peripheral devices through a
computer's parallel port. A type of port that transmits
data in parallel (several bits side by side).
Parameter
A word, number, or symbol that is typed after a command
to further specify how command should function.
Parity A check bit used to make sum of bits in a unit of data
either even or odd (including parity bit). A unit of data
that is 8 bits long would have no parity, and a unit
of data 7 bits long would have an even parity bit to make
an 8 bit word. Parity is used to check a unit of data for
errors during transmission through phone lines or null
modem cables.
Paste To insert information from Clipboard. Information can be
pasted multiple times.
Path A route used in finding, retrieving, and storing files on
a disk. The course leading from root directory of a drive
to a particular file.
PERL The Practical Extraction and Report Language. An
interpreted language for CGI scripts.
PCMCIA A standard format for credit-card-size expansion cards,
used to add features to laptop computers, hand-held
computers, and desktop computers. The acronym stands
for Personal Computer Memory Card International
Association.
PDF Portable Document Format. A PDF file is an electronic
facsimile of a printed document.
Peer-to-peer A network setup that allows every computer to both offer
and access network resources, such as shared files,
without requiring a centralized file server. Macintosh
computers utilize this type of network setup.
Peripheral A piece of hardware that's outside main computer. It
usually refers to external hardware such as disk drives,
printers, and scanners sold by a third party.
PERL Practical Extraction and Reporting Language. A robust
programming language frequently used for creating CGI
programs on web servers.
Perimeter-based Security
The technique of securing a network by controlling access
to all entry
and exit points of the network.
PICS The standard macintosh graphic file format for
animations. Essentially a collection of bit-mapped PICT
images in sequential order, much like movie frames.
PICT/PICT 2 PICT is standard macintosh graphic file format for
graphics that are cut or copied to Clipboard and for
drawings that won't be output on PostScript printers.
This
format is ideal for on-screen presentations, but page
layout programs sometimes have problems with PICT files.
Files are sometimes called metafiles because they can
contain both bit maps and QuickDraw-based objects.
Pixel Picture element. Digital images are composed of touching
pixels, each having a specific color or tone. The eye
merges differently colored pixels into continuous tones.
Pixel Skipping A means of reducing image resolution by simply deleting
pixels throughout image.
PKZIP/PKUNZIP A software compression utility for PC. It allows you to
compress or "zip" a file or a number of files into one
archive file in ZIP file format.
Plug-In Extends capabilities of a web browser, allowing browser
to run multimedia files.
PMT Photomultiplier tube. The light sensing device generally
used in drum scanners.
Policy Organization-level rules governing acceptable use of
computing
resources, security practices, and operational procedures
POP A server using Post Office Protocol, which holds users'
incoming e-mail until they read or download it.
Ports Any server machine makes its services
available to the Internet using numbered ports, one
for each service that is available on the server
How Web Servers and the Internet Work for details).
For example, if a server machine is running a Web
(HTTP) server and an FTP server, the Web server would
typically be available on port 80, and the FTP server
would be available on port 21. A company might block
port 21 access on all machines but one inside the
Port One of several rendezvous points where TCP/IP connections
can be made on a computer. Ports are numbered, with
several locations reserved for specific types of
network activity, such as telnet on port 23, HTTP traffic
on port 80 and USENET news (NNTP) on port 119.
Posterization The conversion of continuous tone data into a series of
visible tonal steps or bands.
ppi/ppc Pixels per inch or pixels per centimeter. Units of
measurement for scanned images.
PPP Point-to-Point Protocol. It provides a method for
transmitting packets over serial point-to-point links.
PRAM Parameter RAM (pronounced pee-ram). A small portion of
Mac's RAM set aside to hold basic information such as
date and time, speaker volume, desktop
pattern, and key-board and mouse settings. PRAM is
powered by a battery, so it doesn't lose settings when
you shut down. Sometimes, however, PRAM data
gets corrupted, causing crashes or other problems.
Primary color A base color that is used to compose other colors.
Process Ink Colors CMYK pigments used in printing processes, chosen to
produce widest range of color mixtures.
Profile The color characteristics of an input or output device,
used by a CMS to ensure color fidelity.
Properties Information about an object, including settings or
options for that object. For example, you look at
properties of a file for information such as file size,
file type, and file attributes.
Protocols The protocol is the pre-defined way that
someone who wants to use a service talks with that
service. The "someone" could be a person, but more
often it is a computer program like a Web browser.
Protocols are often text, and simply describe how the
client and server will have their conversation. The
http in the Web's protocol. Some common protocols
that you can set firewall filters for include:
Protocols When data is being transmitted between two or more
devices something needs to govern controls that keep this
data intact. A formal description of message formats
and rules two computers must follow to exchange those
messages. Protocols can describe low-level details of
machine-to-machine interfaces (e.g., order in
which bits and bytes are sent across wire) or high-level
exchanges between application programs (e.g., way in
which two programs transfer a file across
Internet).
Proxy ARP A technique in which one machine, usually a gateway,
answers ARP requests for another machine. By pretending
to be physical network location of another
machine, gateway takes over responsibility of routing
packets destined for other machine. For instance, a
gateway can proxy ARP for addresses that
gateway identifies as being off local network and that
gateway has a route for. The originating computer
receives gateway's proxy ARP reply and sends
datagram on to gateway, which routes datagram to its
actual destination network.
Proxy A software agent that acts on behalf of a user. Typical
proxies accept
a connection from a user, make a decision as to whether or
not the user
or client IP address is permitted to use the proxy,
perhaps does
additional authentication, and then completes a connection
on behalf of
the user to a remote destination.
A proxy server referred to as application gateway or forwarder
mediates traffic between protected network and Internet
Proxies used instead of router-based traffic controls,
prevent traffic from passing directly between networks.
proxies contain logging or support for authentication.
proxies must ``understand'' application protocol used,
they can also implement protocol specific security
(e.g., an FTP proxy might be configurable
to permit incoming FTP and block outgoing FTP).
Proxy Servers + DMZ A function that is often combined with a firewall is a
proxy server. The proxy server is used to access
by the other computers. When another computer requests a
Web page, it is retrieved by the proxy server and then
sent to the requesting computer. The net effect of this
action is that the remote computer hosting the Web page
never comes into direct contact with anything on your home
network, other than the proxy server.
Proxy servers can also make your Internet access work more
efficiently. If you access a page on a Web site, it is
cached (stored) on the proxy server. This means that the
next time you go back to that page, it normally doesn't
have to load again from the Web site. Instead it loads
instantaneously from the proxy server.
may want to create a DMZ Demilitarized Zone)
it really is just an area that is outside firewall.
Setting up a DMZ is very easy. If you have multiple
computers, you can choose to simply place one of the
computers between the Internet connection and the
firewall. Most of the software firewalls available will
allow you to designate a directory on the gateway computer
as a DMZ.
Proxy service Information from the Internet is
retrieved by the firewall and then sent to the
requesting system and vice versa.
PSN Packet Switch Node; a store-and-forward packet switch
(formerly called an IMP).
Public-domain Software that has no copyright or fee, which means you
can copy, use, and even alter and sell it.
Quality Factor A multiplication factor (between 1 and 2) applied to
output screen ruling to calculate scanning resolution for
optimum output quality. This is also known as halftoning
factor.
Quarter Tones Tones between shadow and midtones are known as 3/4 tones
and those between highlight and midtones are known as 1/4
tones.
Query The process by which a web client requests specific
information from a web server, based on a character
string that is passed along.
QuickTime A file extension for videos or "movies" (like animations)
compressed using their QuickTime format.
R or Return to Quick Index
RAM Random Access Memory. RAM is most common type of
computer memory, and it's where computer stores system
software, programs, and data you are
currently using. It's formally called dynamic RAM (DRAM)
because it's volatile, that is, contents are lost when
you turn off computer (or crash). It's pronounced
ram and measured in megabytes.
Raster A synonym for grid. Sometimes used to refer to grid of
addressable positions in an output device.
Rel Recorder element. The minimum distance between two
recorded points (spots) in an imagesetter.
Remote system Another computer on Internet to which you connect.
Interactions between computers are often described using
terms "local" and "remote" systems. The local
system is your computer and remote system is other
computer.
Res A term used to define image resolution instead of ppi.
Res 12 indicates 12 pixels per millimeter.
Resampling An increase or reduction in number of pixels in an imge,
required to change its resolution without altering its
size. See also down-sampling and interpolation.
Resolution
In general, this refers to how sharp and clear an image
looks on screen or on paper, and how much detail you can
see. It's usually determined by number of dots (or
pixels) per square inch (the more there are, higher
resolution) and is used to describe printers, monitors,
and scanners.
RFC Request For Comments; technical note series which began
in 1969 describing DARPA and Internet research and
development, particularly in areas of protocol
design and internetworking. Not all (in fact very few)
RFCs describe Internet standards, but all Internet
standards are written up as RFCs.
RGB Red, green, and blue are primary colors of light
perceived by eye.
RIP Routing Information Protocol used by Berkeley UNIX
systems to exchange routing information among a set of
computers attached to a network. RIP packets are sent
and received by a program called routed.
ROGER On-line catalog at UCSD for books and other material in
libraries at University of California at San Diego.
ROM Read-Only Memory. It's like software that's hard-wired
into your computer - basic, permanent information that
tells it things like how to load up operating system
when you turn it on.
route packet takes from source to destination
determined by routers between source and destination.
packet itself only says where it wants to go
( destination address),
to include information to tells route packet should take
name ``source routing''.
an attacker can generate traffic claiming to be
from a system ``inside'' the firewall.
In practice, source routing is very little used.
main legitimate use is in debugging network problems
or routing traffic over specific links for congestion
control for specialized situations.
Router A special purpose computer that attaches to two or more
networks and routes packets from one network to other. A
router uses network layer addresses (such as
IP Addresses) to determine if packets should be sent from
one network to another. Routers send packets to other
routers until they arrive at their final destination.
rpi Rels (recorder elements) per inch. A measurement of
number of discrete steps that exposure units in
imagesetting devices can make per inch.
RS-232 Interface between Data Terminal Equipment (DTE) and Data
Communications Equipment (DCE) employing Serial Binary
Data Interchange, a standard set by
international standards organization - Consultative
Committee on International Telegraphy and Telephony. The
interface between a terminal to a modem for
transfer of serial data.
RTF Rich Text Format. A file format for text files that
includes formatting instructions. Also called Interchange
Format.
S or Return to Quick Index
Sampling The process of converting analog data into digital data
by taking a series of samples or readings at equal time
intervals.
Saturation
The extent to which one or two of three RGB primaries
predominate in a color. As quantities of RGB equalize,
color becomes desaturated towards grey or white.
Scanner A device that converts images (such as photographs) into
digital form so that they can be stored and manipulated
on computers.
Screen Frequency The number of rows or lines of dots in a halftone image
within a given distance, normally stated in lines per
inch (lpi) or lines per centimeter (lpm). A frequency of
200 lpi
would only be used in high-quality printing.
Screen Ruling
Another term used for screen frequency.
Screen Saver A moving picture or pattern that is displayed on screen
when no activity takes place for a specified period of
time.
Scripts
A type of program that consists of a set of instructions
for another application or utility to use.
Screened Host A host on a network behind a screening router. The degree
to which a
screened host may be accessed depends on the screening
rules in the
router.
Screened Subnet subnet behind a screening router.degree to whichsubnet may
be accessed depends on the screening rules in router
Screening Router A router configured to permit or deny traffic
based on a set of
permission rules installed by the administrator.
Scroll Bar The bar that appears at right side or bottom of a
window that contains more information that can be
displayed. The scroll bar is used to scroll an object or
parts of
a document into view when entire object or document does
not fit in window.
SDSUnet San Diego State University Network. The backbone network
that connects multiple buildings on SDSU campus.
Search Engines A type of software that creates indexes of databases or
Internet sites based on titles of files, key words, or
full text of files.
Second Original High-quality, contone reproduction of an image, intended
to be identical to original.
Secondary Color Color obtained by mixing two primary colors. Although
known as primary colorants, C,M, and Y are secondary
colors of light. Red plus green produce yellow, for
example.
Serial Cable/Serial Port
A cable used to connect peripheral devices through a
computer's serial port. Normally a 25-pin connector on
each end, yet can be a 9-pin on one. A Serial Port can
either be plugged into an expansion slot on motherboard
of your computer or built into motherboard itself. Serial
ports are used for such devices as printers, mice,
and modems.
Server A computer that shares its resources, such as printers
and files, with other computers on network. An example of
this is a Novell NetWare Server which shares its
disk space with a workstation that does not have a disk
drive of its own.
Service (NT service) A process that performs a specific function in Windows NT
and can be called by various other programs. Windows NT
provides tools to monitor and administer
services.
Shadow
The darkest area of an image.
Session Stealing See IP Splicing.
Shareware Software that you can try before you buy. It's
distributed through on-line services, BBSs, and user
groups. You're allowed to try it out and give copies to
others, but if
you want to keep using it, you must pay registration
fee.
Shockwave A set of programs that allow Macromedia Director
animation files to be played over internet with a web
browser.
Site Organization or facility where a host is located.
Site-license
Through negotiations with a vendor, a renewable fee has
been paid to allow a fixed number of copies of
copyrighted software at one site.
SLIP Serial Line Internet Protocol. A protocol used to run IP
over serial lines, such as telephone circuits or RS-232
cables, interconnecting two systems.
SMTP Server Hijacking (Unauthorized Relaying)
spammer take many thousands of copies of a message
and send it to a huge list of email addresses.
Because these lists are often so bad,
and in order to increase speed of operation for spammer,
many simply send all mail to SMTP server that
will take care of actually delivering mail.
Of course, all of bounces, spam complaints, hate mail,
and bad PR come for site was used as a relay.
Bugs in Applications
web servers, mail servers, and other Internet service
software contain bugs that allow remote (Internet) users
to do things
ranging from gain control of the machine to making that
application crash
and just about everything in between.
SMTP (Simple Mail Transport Protocol) - used to
send text-based information (e-mail)
SNMP (Simple Network Management Protocol) - used
to collect system information from a remote
computer
SMTP hijacking SMTP is the most common
method of sending e-mail over the Internet. By
gaining access to a list of e-mail addresses, a
person can send unsolicited junk e-mail (spam) to
thousands of users.
SMTP Simple Mail Transfer Protocol. Internet standard protocol
for transferring electronic mail messages from one
computer to another. SMTP specifies how two mail
systems interact and format of control messages they
exchange to transfer mail.
SOCKS generic proxy system can be compiled into client-side
application to make it work through afirewall.
easy to use, but doesn't support authentication hooks or
protocol specific logging.
http://www.socks.nec.com/.
Socket Logical address of a communications access point to a
specific device or program on a host.
Source routing In most cases, the path a packet
travels over the Internet (or any other network) is
determined by the routers along that path. But the
source providing the packet can arbitrarily specify
the route that the packet should travel. Hackers
sometimes take advantage of this to make information
appear to come from a trusted source or even from
inside the network! Most firewall products disable
source routing by default.
Spam Typically harmless but always annoying, spam
is the electronic equivalent of junk mail. Spam can
be dangerous though. Quite often it contains links to
Web sites. Be careful of clicking on these because
you may accidentally accept a cookie that provides a
backdoor to your computer.
* Redirect bombs - Hackers can use ICMP to change
(redirect) the path information takes by sending it
to a different router. This is one of the ways that a
denial of service attack is set up. here!
SPAM Refers to practice of blindly posting commercial
messages or advertisements to a large number of unrelated
and uninterested newsgroups.
Speckling Isolated light pixels in predominantly dark image areas,
sometimes caused by incorrect readings or noise in
scanning device.
Spectral Highlight A bright reflection from a light source containing little
or no detail.
Spectrophotometer An extremely accurate color measurement device using a
diffraction grating to split light into its components
wavelengths, which are then measured by numerous light
sensors.
Spreadsheet A number-related document whereby calculations and
formulas are applied to data organized in rows and
columns of cells.
SQL Structured Query Language, a syntax used by many database
systems to retrieve and modify information.
SSL work through the firewall
SSL is a protocol that allows secure connections across
the Internet.
Typically, SSL is used to protect HTTP traffic. However,
other protocols
(such as telnet) can run atop SSL.
Enabling SSL through your firewall can be done the same
way that you would
allow HTTP traffic, if it's HTTP that you're using SSL to
secure, which is
usually true. only difference is that instead of using
something that
will simply relay HTTP, you'll need something that can
tunnel SSL. This is a
feature present on most web object caches.
You can find out more about SSL from Netscape
Staircasing See Aliasing.
Start/Stop Bits A start bit signals start of a unit of data in
asynchronous communications. A stop bit signals stop of a
unit of data. The unit can vary in length depending on
protocol.
Stateful inspection A newer method that doesn't
examine the contents of each packet but instead
compares certain key parts of the packet to a
database of trusted information. Information
traveling from inside the firewall to the outside is
monitored for specific defining characteristics, then
incoming information is compared to these
characteristics. If the comparison yields a
reasonable match, the information is allowed through.
Otherwise it is discarded.
Subnet Address An extension of Internet addressing system that allows a
site to subdivide a single Internet address to cover
multiple physical networks. This is done by dividing up
host address part of an IP Address into a local network
number and host address number.
Substrate The base material used to carry out or support an image,
for example, paper or film.
Subtractive Primaries
Another term for primary colorants.
Supersampling The capture of more grey levels per color than is
required for image manipulation or output. This
additional data allows shadow details to be heightened,
for example.
Syntax Error Occurs when a user (or programmer) has put words in an
order that a program does not understand.
T or Return to Quick Index
T1 An AT&T term for a digital carrier facility used to
transmit a DS-1 formatted digital signal at 1.544
megabits per second.
T3 A term for a digital carrier facility used to transmit
Tags Formatting codes used in HTML documents. These tags
indicate how parts of a document will appear when
displayed by a Web client program.
Taskbar
An area that runs across bottom (usually) of Windows 95
desktop. Running applications are represented as buttons
on taskbar, current window is shown
as a depressed button, all other applications are
displayed as raised buttons.
TCP (Transport Control Protocol) - used to break
apart and rebuild information that travels over
the Internet
TCP Transmission Control Protocol. This is a transport layer
protocol that establishes a reliable, full duplex, data
delivery service used by many TCP/IP application
programs.
The TCP software uses IP protocol to transmit
information across Internet.
TCP/IP Transmission Control Protocol/Internet Protocol. A set of
protocols, resulting from ARPA efforts, used by Internet
to support services such as remote login
(TELNET), file transfer (FTP) and mail (SMTP).
Telnet used to perform commands on a remote
computer
A company might set up only one or two machines to
handle a specific protocol and ban that protocol on
all other machines.
TELNET The Internet standard protocol for remote login (terminal
connection) service. TELNET allows a user at one site to
interact with a remote timesharing system at another
site as if user's terminal were connected directly to
remote computer.
Terminal Communication device that lets a user send information to
a computer by typing on a keyboard, and prints responses
from computer on paper or a screen.
Terminal Mode Many communications programs allow you to mimic a
computer terminal, which is basically a keyboard and CRT
display and/or a printer. A common terminal mode
emulator is VT-100.
Terminal Ready (TR) This light is illuminated when your computer has turned
on RS-232 (serial) interface. Sometimes this light will
not come on until you have loaded your
communications software into memory.
Terminal Server A small, specialized, networked computer that connects
many terminals to a LAN through one network connection. A
terminal server can also connect network users
to asynchronous ports or a host.
Thermal Wax Transfer A printing process using small heating elements to melt
dots of wax pigment on a carrier film, which are then
transferred to paper or transparent film by contact. This
differs from dye sublimation process in that individual
dots do not fuse together, so thermal wax transfer
appears to be of a lower resolution.
Thread In context of Windows NT, a thread is sometimes used to
refer to an NT service. Threading also refers to a
low-level system architecture concept used in some
multitasking operating systems.
Threshold The point at which an action begins or changes. The
threshold setting used in scanning line art determines
which pixels are converted to black and which will become
white. The threshold defined in USM process determines
how large a tonal contrast must be before sharpening will
be applied to it.
TIFF Tag Image File Format. A graphic file format, TIFF files
are also bit maps, but they can be any size, resolution,
or color depth. It is most versatile, reliable, and
widely
supported bit-mapped format and is standard format for
saving scanned images. However, format does have several
variations which means that occasionally
an application may have trouble opening a TIFF file
created by another program.
Title bar The horizontal bar at top of a window. The title bar
shows name of window.
Tone Curves
Also known as gamma curves. These are used to smoothly
adjust overall tonal range of an image, or individual
tonal ranges of each color channel.
Toolbar A collection of buttons that typically make more common
tools for an application easily accessible.
TSR
Terminate and Stay Resident.
U or Return to Quick Index
Trojan Horse A software entity that appears to do something normal
but which,, contains a trapdoor or attack program.
Tunneling Router A router or system capable of routing traffic
by encrypting it and encapsulating it
for transmission across an untrusted network, for
eventual de-encapsulation and decryption.
Social Engineering An attack based on deceiving users or administrators
at the target site. Social engineering attacks
are typically carried out by
telephoning users or operators
and pretending to be an authorized user,
to attempt to gain illicit access to systems.
UDP (User Datagram Protocol) - used for
information that requires no response, such as
streaming audio and video
USM Unsharp masking. A process used to sharpen images.
UUCP UNIX-to-UNIX Copy Program. This was initially a program
run under UNIX operating system that allowed one UNIX
system to send files to another UNIX
system via dial-up phone lines. Today, term is more
commonly used to describe large international network
which uses UUCP protocol to pass news and
electronic mail.
Uncover A database of book reviews, magazines, and articles,
including FAX article delivery. It provides table of
contents information for over 14,000 journals in all
disciplines
held by libraries in Colorado Academic and Research
Libraries consortium and provides on-line access to ERIC,
at education database. Coverage for most
journals begins with 1989.
UNICOS A version of UNIX operating system adapted for CRAY
computers.
UNIX An operating system developed by Bell Laboratories that
supports multiuser and multitasking operations.
Upload
Send a file to another computer using a modem.
UPS Uninterruptible Power Supply. A unit that switches to
battery power whenever power cuts out.
URI Uniform Resource Identifier, a string of characters that
represents location or address of a resource on Internet
and how that resource should be accessed. A
URI is a superset of Uniform Resource Locator.
URL Uniform Resource Locator, a string of characters that
represents location or address of a resource on Internet
and how that resource should be accessed. World
Wide Web pages are assigned a unique URL. Each hyperlink
on a web page contains URL of page to be linked to.
http://rohan.sdsu.edu/glossary.html is URL
for this page.
USENET A network of newsgroups. There are thousands of
newsgroups available through USENET. Each one covers a
specific topic or subject area.
User Id The string of characters that identifies you. The name by
which you are known to network. Also known as username.
UUCP UNIX-to-UNIX Copy Program, a program that lets you copy
files between UNIX systems. UUCP protocols are used to
transfer news and Email messages through
USENET. V or Return to Quick Index
Veronica Very East Rodent-Oriented Net-wide Index to Computerized
Archies. An index searcher of Gopher repositories.
Searches are based on keyword criteria to help users
find Gopher-based information without doing a
menu-by-menu, site-by-site search.
Videodisc A 12-inch disk that's similar to an audio CD but holds
visual images (such as high-quality movies) as well as
music. Also called a laserdisc.
Virtual Network Perimeter
A network that appears to be
a single protected network behind firewalls,
which actually encompasses encrypted virtual links over
untrusted networks.
Virus A replicating code segment that attaches itself
to a program or data file. Viruses might or might
not not contain attack programs or
trapdoors. Unfortunately, many have taken
to calling any malicious code
a ``virus''. If you mean ``trojan horse''
or ``worm'', say ``trojan horse'' or ``worm''.
Viruses Probably the most well-known threat is
computer viruses. A virus is a small program that can
copy itself to other computers. This way it can
spread quickly from one system to the next. Viruses
range from harmless messages to erasing all of your
data.
Virus A program that replicates itself from one file or disk to
another without your consent. They are spread through
floppy disks, networks, and on-line services and can go
undetected (unless you have an antiviral utility) until
something goes wrong. Some viruses deliberately destroy
data, and even those designed to be benign can cause
crashes, slowdowns, and file corruption.
VMS Digital Equipment Corporation proprietary operating
system which runs on VAX series of machines.
VOD Video On Demand.
VRAM Video RAM. A type of memory dedicated to handling image
displayed on a monitor. VRAM is built into many Macs, and
it also comes on display cards.
W or Return to Quick Index
WAIS Wide Area Information Server. WAIS is best at searches
for various sources of academic information that has been
indexed based on content. Its indexes consist of
every word in a document and each word carries same
weight in a search.
Wallpaper
A graphical pattern displayed on desktop.
Web browser Also known as a Web client program, this software allows
you to access and view HTML documents. Netscape, Mosaic,
Lynx, WinWeb, and MacWeb are some
examples of Web browsers.
Web page A document created with HTML that is part of a group of
hypertext documents or resources available on World Wide
Web.
Web walking Using a Web client program to move through documents
available on World Wide Web. This casual browsing nature
of navigating WWW has also been
referred to as strolling, crawling and jumping.
Webmaster A person or group of people who maintain and administer a
web server. Webmaster also refers to a standard Email
address at most web hosts where comments and
questions can be sent.
White Point A movable reference point that defines lightest area in
an image, causing all other areas to be adjusted
accordingly.
WHOIS An Internet program which allows users to query databases
of people and other Internet entities, such as domains,
networks, and hosts. The information for people
generally shows a person's company name, address, phone
number and email address.
Wide Area Network (WAN)
Network spanning multiple geographic distances, usually
connected by telephone lines, microwave, or satellite
links.
Wildcard A character (usually * or ?) that can stand for one or
more unknown characters during a search.
Windows Microsoft software that adds a Mac-like graphical user
interface to IBM PCs and compatibles.
Word Processing Entering, editing and formatting text with use of
spelling checkers, outlining, tables, footnotes, and
tables of contents.
Workstation A networked personal computing device with more power
than a standard IBM PC or Macintosh. Typically, a
workstation has an operating system such as UNIX that
is capable of running several tasks at same time. It has
several megabytes of memory and a large high-resolution
display.
Worm standalone program that, when run, copies itself
from one host to another, and then runs itself
on each newly infected host. The widely
reported ``Internet Virus'' of 1988 was not a virus
at all, but actually a worm
WWW World Wide Web or W3 is hypermedia document presentation
system that can be accessed over Internet using software
called a Web browser.
WYSIWYG What you see is what you get. The image you see on
screen matches what will print on paper. Pronounced
wizzy-wig.
X.25 A data communications interface specification developed
to describe how data passes into and out of public data
communications networks. The CCITT and ISO
approved protocol suite defines protocol layers 1 through
3.
Zipped Compressed version of a program or document.