glossary of computer terms
antenna is a tuned electromagnetic device that can send and recieve broadband signals at particular frequencies.
Applet usually a graphic Java based application that runs within an HTML document, Windows also runs Applets, that are not Java based
ARPAddress Resolution Protocol a protocol in the
TCP/IP suite used to associate logical (IP) to physical(MAC) address
was created by Microsoft in hope to beat the Java technology and a part now of Microsoft's Internet Explorer browser. ActiveX are usually found on Web Pages, and they can run programs remotly ona client's PC(very bad thing in my opinion, because people can then write hostle applets that can remotly read your HD, delete files, ets). Developers use it to build user interactivity into programs such as Email readers.
Controls that use ActiveX technology. These controls can be downloaded
automatically from a Web page and executed by a Web browser.
Advanced Streaming Format (.ASF)
A data format for streaming audio and video content, images, and script commands in packets over a network. ASF content can be an .asf file or a live stream generated by Windows Media Encoder. ASF content that is in the process of being delivered over a network is called an ASF stream
baud sometimes denotes modem speed. Baud represents
the oscillation of a sound wave on which one bit of data is carried. In
other words, the term baud is used to measure the
the modemn speed that descibes the number of state stansitions that occur
in one second on an analog telephone line.
In earlier modems the term baud and bps could be
used intenchangably: a 300 bps modem had 300 oscillations of sound waves
each second. However with new compression technology, the number of bits per second increased past the number of osillation per second. For example, a modem that can transmit at 28,800 bps may actually be transmitting at 9,600 baud.
The amount of data that can be transmitted in a fixed amount of time.
On computer networks, higher bandwidth indicates faster data transfer.
Network bandwidth is expressed in bits per second (bps).
In the Windows Media Services environment, Windows Media Administrator
can specify bandwidth constraints for a variety of functions, including
maximum aggregate bandwidth unicast from a server, maximum bandwidth for a
single unicast stream from a server, and continuous bandwidth used by a
multicast file transfer from a server
baseband is when a computer transmits its data,
the signal occupies the entire bandwidth of the network medium. in contrast, in broadband, multiple signals can travel at one time. a cable TV network is broadband.
The speed at which binary content can be streamed across a network. It usually is measured in kilobits per second (Kbps)for example, 28.8 Kbps. Windows Media Encoder and Windows Media Administrator have settings for the bit rate of ASF content.
broadband is when multiple signals can travel at one time. a cable TV network is broadband.
Describes how a client experiences receiving a stream. A broadcast stream can be multicast or unicast. In a broadcast connection, the client is passive and does not control when the stream starts or stops. In contrast, in an on-demand connection, the client is active and controls when the stream is started or stopped
An area of memory reserved for use as an intermediate repository in
which data is temporarily held while waiting to be transferred between two
locations. A buffer ensures that there is an uninterrupted flow of data between computers
browser -a graphical software tool used for "surfing" the Internet. It reads HTML documents and accesses the WWW, FTP, NNTP, est. The main two are Internet Explorer from Microsoft and Netscape Commuicator. There is also Opera from opera.net and a few less known ones. Sun is supposed to come out with a broswer of its own totally running on its Java technology. Older browsers are Mosiac, Archie and Veronica
cache usually a storage location that keeps recently or frequently requested material ready for the user. Usually a CACHE is faster than a storage device. It is used to speed tranfer of data or instructions faster. Your PROXY, your BROWSER, your PC all have several caches. Problem with CACHE is the data is usually left to lie around in them and CACHES can be a BIG security and privacy loophole.
client refers to a user's computer connecting to a
server or host on the Internet and requesting some kind of service as in files, documents ets
client Typically, the software that makes requests in client/server communications. Client software requests connections and communicates with servers.
Short for compressor/decompressor. An algorithm or scheme used when recording digital video or audio. A codec is used, for example, when video is transmitted over the Internet; the video is compressed on the sending end and decompressed on the receiving end. Windows Media Tools provides a choice of codecs for ASF content. Users can select a codec based
on the audio or image quality, and image size preferred.
Every web site you visit places a small surveillance file on your HD that
tracks how often you vsit that site, what you look at, which links you
click on, ets. That file is called a cookie. It is just like a
digital bar code on your back - a user ID - so that it can identify your
interests, habits and preferences, so for example when you return next time
you wont' have to re-enter your PW. Other than that, cookies are useless
and can reveil detailed personal information about you to its data
banks because the Web sites continuosly send and read their own
cookies from your HD.
Cookies are commonly used in search engines, shopping carts,
Web-based e-mail and secure e-commerce applications, thus helping
admen, administrators identify track and classify traffic by individual user.
Generally cookies hold and ID assigned to you by the
web site, the date and the time you accesed the site, any PassWords you might need, ets. cookies are used by sites and ads for identification and accounting purposes.cookies are sent in the HTTP header after each TCP session has been established inside a cpecial folder designed for that purpoise. In Windoze IE used the C:\Windows\Cookies, while Netscape and Opera have the file inside their own folders.
All this arises several troubling questions nobody has been able to give a
fully satisfying answer to. WHat to the adm of the Web sites that plants a cookies on yor HD DO with the info?..How much info can the cookie contain about you as a user? Can a cookie be read by all other web sites a user visits subquentially? Do we REALLY NEED cookies?
For more info read RFC 2109 at http://www.ietf.org/rfc/rfc2109.txt
An IP address and port, from which a listening client can receive a multicast. A client instructs its network card to listen for packets arriving at the destination address and port.
distributed Component Object Model (DCOM)
An extension of the Component Object Model (COM). DCOM enables software components to communicate directly with each other across networks, including the Internet and intranets, in a reliable, secure, and efficient manner.
DNS Domain Name System A Distrubuted database system primary used to map host
names to IP addresses to simplify our lives. For example the IP address of www.microsoft.com is 220.127.116.11. So instead of us rememebring 207.46.bla bla, all we need to do is type www.microsoft.com and the DNS system looks up the name in its
data base and directs us toward the correct place. See RFC 1034 and RFC 1035.
domain everyone defines a domain a little bit differently, but in Internet terms a domain is a group of computers centered around a SERVER and all sharing the same name. which is the 3 letters designator at the end of the Iternet address such as "com","gov", "org", ets. There are DOMAINS within DOMAINS. Thus all domains in USA also carry "us" to show they are in USA, all the ones in Russia are named "ru", ets.
DOS Disk Operating System - Long, long ago in a
galaxy far away, no just back in the 1980's DOS was the O/S system used by PC to get all the different computer parts to talk to each other and work together. Its history is a bit mirky but generally Microsoft is credited with DOS development. Up to Win95, all PC ran DOS.
Denial of Service Attack (DOS) Flooding an IP address with data, causing computers to crash or lose their connection to the Internet. Most DOS attacks are aimed at large Web servers, with the objective of rendering the target site unavailable to other visitors.
Distributed Denial-of-Service (DDoS ) Attack: Using multiplecomputers to launch a DoS attack. commandeers several outside computersand uses them as platforms to launch the attack, magnifying its intensityand cloaking the hacker's identity.
Asked Questions. Put the first letters together and you get a FACT -i.e. FAQ. usually documents on the Intrent written by people about specific topic
who are tired of answering the same questions over and over again. That is how I began
writing my little notes on security and privacy on The Internet.
A special-purpose system(hardware, software or a server) that sits between the public side of an internet connection and the private network or a PC to which it is attached. It filters all inbound and outbound traffic to detect any snooping and or break in attempts, and decides which connections are to be allowed according to predetermined rules
FTP one of the first, File Transfer Protocol is used for distribution of documents between systems. The documents reside on FTP servers where anyone with a FTPbrowser can visit. Unlike WWW server, FTP use simple NON graphics interface and a simple DOS like dir drives naming system. Usually, a lot of the shareware, software you get resides on FTP servers. The RFC number dealing with it is 959. FTP provides or many data format options and is much widely used that Trivial File Transfer Protocol.
headersthe poretion of a data packet that contains the IP address and other identification data. It is used to direct and control headers as they travel across a network.
host is another term for a server on the Intrenet. When youy connect to your ISP, you are connecting to their main SERVER
HTML - Hyper Text Mark up Language A way of scripting the documents on WWW - World Wide Wen servers. See RFCs 1886 and WWW.
HTTP Hyper Text Tranfer Protocol -One of the main TCP/IP protocols used to transfer hypertext and other documents and images that are on the World Wide Web servers
hypertext in essence a "supertext". It acts as a link or a point to other simular documents on other Web Pages. It is created with HTML.
Integrated Services Digital Network (ISDN)
A completely digital telephone/telecommunications network for carrying voice, text, images,and video traffic at high speed by sending digitally-encoded signals.
Internet Protocol address (IP address)
A 32-bit number that is the unique IP address of each computer or device on the Internet. This number specifies a physical location, or node, on the network.
Internet Server API (ISAPI)
A framework for creating a dynamic link library (DLL) to provide Internet server-side
functionality. Windows Media Services uses ISAPI to provide one of the options for security.
A network belonging to an organization. Only members of that organization have access to it.
An intranet that is connected to the Internet usually is protected by a firewall or other device
Internet The common abriviation of the term
InterNetWork, it refers to the worldwide collection of combined computers networked together.
It began in the late 60s funded by the US department of Defence and Technology and today links millions of computers and computer networks worldwide. For some reason, most people think World Wide Web(HTTP) is The Internet, but actually WWW is just one of the networks that is part of the internet but not all of The Internet. The Internet also includes USENET(NNTP), FTP, e-mail and many other services.
One of the 2 primary protocols of
TCP/IP . It is responsible for network routing,
and outbound message delivery. It handles the actual transfer of data on the Internet The internet protocol-not the same as the IP number. See RFC 791
IP address or IP NUMBER- just like a telephone
number your Internet Protocol is a unique numeric address used to identify your PC on The Intrnet. so you can send and recieve data. When your PC is connected to The Internet it becomes knows a a NODE on The Internet.
Java is an ambitious software project created my SUN Microsystems, it was said to be able to run on any system. Immediatly seeing the treat to their Windows system,
Microsoft wentr on the offensive and tried to undermine it by introducing Active X.
not the same as Java.
Java Scriptwas introduced by
Netscape as means of running APPLETS on a remote users machine( not a good thing in my opinion)
JPEG - Joint Photographic Experts Group standard was created for compression of still video images. It removes redundant information from an image, compresses it and reproduces frames up to 30 frames per second. when this is applied to video,it is called M-JPEG or MPEG, (Motion Picture Experts Group) or MPG
Close at hand or restricted to a particular area. In communications, a local device is one that can be accessed directly rather than by means of a communications link. In information processing, a local operation is one performed by the computer at hand rather than by a remote computer. For example, the server computer on which Windows Media Services is installed is the local computer with respect to that server
logical drive the software counterpart of a physical disk drive. Each logical is assigned a letter such as C, D, E,. Physicial drives can be split into partitions and each partition can be split into multiple logical drives.
MAC address is the unique build-in number of an
NIC (Network Interface Card) and it's called that
because it's handled by the Media Access Control
function in the NIC. The MAC addresses are hardwired into the interface and
are in 6 2 digit hexadecimal numbers separated by colons for example
00:60:97:33:90:A3. You only have a MAC address if you on Eathernet for example.
Media Access Control is a sub layer of the
Data Transport layer in the ODI
model, where the Network Interface Card(NIC) can directly address
the network media (cable or whatever).
Microsoft Internet Explorer
is the Windows-based Web browser produced by Microsoft Corporation.
It supports Dynamic HTML, Java, Activer X, Cascading Style Sheets, SSL, ets. It features include History, Search, Favorite links, ets.
Microsoft Windows Media Player
A software program run by the client PC's than can play movies, MP3 files, or receive streaming media from a Windows Media server. This Player plays fiels with the following extentions: .asf, .MPEG, .MPG, MP3, ets. It can either can run as a stand-alone client executable program or can be embedded ina Web page, C++ program, or a Microsoft Visual Basic program that uses the client ActiveX control. Microsoft Windows Media
MPEG, (Motion Picture Experts Group) or MPG is a new binary file compression format for multimedia files such as movies, music ets. MPEG-1 supports video at 352 X 240 pixels resolution at rate of 30 frames-per-second, MPEG-2 up to 1280 X 720 pixels at rate of 60 frames-per-second. MP3 is a format for 16 bit near-CD quality
music files. To use them you need software such as the free Microsoft Media Player which can be d/l from www.microsoft.com
A one-to-many connection in which multiple clients can receive the same stream from a server. To receive a multicast, a client must have access to a multicast-enabled network. In contrast, a unicast is a one-to-one connection in which one client receives a distinct stream
from a server.
A network that has routers that can interpret Class D IP addresses.
modem (MOdulator/DEmodulator) is used by
computers to convert digital signals into analog for transmition over
NIC Network Interface Card is used by LAN networks, or Ethernet etworks instead of a modem. The name is self expalnatory.
NNTP Network News Transfer Protocol is one if the oldest Internet protocols, developed in the 1970s to exchange text articles. Its also known as USENET. Now days it used all other files types, including movies, music, soft, ets. It operates independently from WWW, on its onw NNTP servers and uses so called News Groups, each one for specific topic, ranging from computers to cooking to supermodels, or fringe groups like why people hate Barny the dinasour(alt.binarie.die.barny die group.
O/S - Operating System . Your PC needs an O/S so all its different parts-motherboard, hard drive, floppy drive, , CPU, CD ROM can "talk" to each other and share data and info. Some well known OS are DOS, Win 95, 98, Win 2000, NT, O/S 2 Warp, UNIX, Linux and its many flavors-Red hat, Caldera, free BSD, ets
PPP Point-to-Point Protocol is what most ISPs use
today to connect their customers(you) to the Net because it allows IP addresses to be
dynamically assigned. It provides BOTH Physical and
Data Link layers, thus effectevly turning a modem into a
Network Interface Card (NIC), so it can support
multiple protocols including IP,
IPX, NetBEUI. It also
supports compression and data checking, which makes it more stable faster
and reliable than SLIP.
all data on the networks is broken down into packets for easy handing, then it is transmitted over. packets are of fixed size, and are routed between a source and a destination. they contains binary information that represents both data and a header containing an ID number, source address, and destination address
think of a port as a door or/and window. there are about 5000 indivigual ports. Ports are used on the 'net, as each indivigual protocol used a specifically desigend port. The HTTP protocol for example uses port number 80, 8080 or 3127. A port is represented by a number that is part of a URL. There are the well known ports I.E. they have been asigned to be used by FTP(port 21), NNTP(port 119), ets and not so well known ports. Usually these ports are on the server, the client grabs any available ports. So a port is both an entry and an exit point. In computer lingo, a PORT is a logical address with speculized function. Some trojans and viruses are written to use specific number ports. Ports are a huge security risk and it's a good idea to learn to watch your open ports so you can know whats going on on youre system while online.
protocol- simular but not exaclty like a software. Protocols are a set of instructions and rules used by computers in a network to communicate together. When two computers are using the same protocol thats how they can "talk" to each other and ":understand" each other. There are many different sets of PROTOCOLS like TCP/IP, FTP, HTTP, NTTP, SMTP(e-mial), ets.Another way to explain protocols is to think of them as rules and procedures for
communication. Just as when people travel to other countries they must be familiar with the proper way to meet, greet, and communicate with the locals, so do computers.
If two computers ona network can communicate with one another
successfully, they must share a common set of rules about how to communicate.
At a minimum such rules must include how to interpret signals, how to
identify "oneself" and other computers on the network, how to initiate and
end network comunication and how to manage information exchange across the
medium. Such collection of agreed upon rles are called protocols.
So a protocol(s) is a rigidly defined "set of rules" for communication across a network. So a protocol is a set of formats and procedures that enable computers to exchange information.
proxy a server somewhere on The Internet that can be used to mask your "real" address(the IP number) and point of departure. It can also be used
to speed you Intrernt "surfing" and it offers anonim osity and privacy protection. Most ISP, colleges and Univercities offer free proxies for the public to use.
A server computer that controls, monitors, directs internet-based traffic between networks on the Internet or companies' private intranets.
Not in the immediate vicinity or not directly accessible. A computer or other device located inanother place (room, building, or city) and accessible through some type of communications link.
A device that connects two or more networks, and carries data forward. A router determines where the destination computer is located, and then finds the best way to transmit the data there.
For Comments. The offical documentation describing protocols and other hard core technical information related to The Internet. Most RFCs begin as drafts and are duscussed and finally become the place to look for offical information on Internet information.
server is a computer that provides shared resources (files and directories, printers and databases) to CLIENTS accross a network.
socket is the combination of the IP address plus the local and remote port. a socket is a virtual line that is established beteeen your PC and the server you are using. it can be mapped as a line streaching across the net, with your PC as the starting
point and the server as the ending.
TCP/IP Transmition Control Protocol/Internet Protocol-represents the set of protocols used on the Internet. It uses the OSI model and incliuudes connecting, keeping the connections active, sending and receiving data and much
telnet is another very useful and popular protocol. The name TELNET doesn't mean anything. See RFC 854 and 855. TELNET provides remote terminal emulation, or in normal English you can use it to attach yourself to a remote terminal that could be hundreds of miles away and use it like you are sitting right infront of it.
UDP User Datagram Protocol thatis connectineless TCP/IP protocol for data transport which has no error checks and is often used by trojans and viruses.is a protocol that doesnt establish a permanenet TCP connection. It is fast, but unreliable, as it doesnt perform check on sent data. Difficult to detect if you are looking for it.
It runs on top of IP networks.
URL Uniform Resource Locator is the specific full
address of an Internet "resource" like a web page for example.
WWW - World Wide Web sometimes called the World Wide Wait...no, just kidding. World Wide Web was invented by Brandon Lee in 1992. Currently the most popular and fastest growing part of the Internet. Most people mistake the WWW for The Internet itself. WWW are just a bunch of servers running the same WWW protocol known
as HTTP. WWW uses the HTML as a way of creating "Web Pages"
video capture card
An add-on board for providing digitized images on a computer.
With a video capture card, you can provide live camera or VCR input to
Windows Media Encoder.
As usual, this is a work in progress, just like everthing