Business Glossary

an ITU-T (formerly CCITT) standard protocol that defines a standard way of arranging data in packets. Each packet contains information indicating which computer sent it and which computer should receive it. See packet. X.25 has been adapted for amateur packet radio, and the adapted version is called AX.25.

the network communication protocol built into Macintosh computers.

a protocol for using one computer as a terminal on another; only textual communication is supported, not graphics.Telnet is widely used to access UNIX systems remotely. To use it, type telnet or tn at a command prompt, or type a URL such as telnet:abc.xyz.com into your browser.

a communication protocol developed by Real Networks (www.realaudio.com) that allows audio signals to be broadcast over the Internet. The user hears the signal in real time, rather than waiting for an audio file to be downloaded and then played. RealAudio is used to distribute radio broadcasts.

an ITU-T standard for compression of data sent by modem, replacing V.42 bis and providing greater compression.

an ITU-T standard for sending data by modem over telephone lines, similar to V.90 except that connections are established more quickly and the user can interrupt the connection to take a voice telephone call, then return to it without loss of data and without having to dial up again. That is, it is fully compatible with Call Waiting.

a standard protocol for parallel data transmission to and from microcomputer equipment, especially printers. It was originally used on Centronics printers. The parallel port of a microcomputer is normally Centronics-compatible. See also IEEE 1284; protocol.

The connector usually used with a Centronics interface is similar to one type of SCSI connector but has 36 connections instead of 50 (Figure 54).

a standard format for transmitting data in packets from one computer to another. It is used on the Internet and various other networks. The two parts of TCP/IP are TCP, which deals with construction of data packets, and IP, which routes them from machine to machine.

a widely used, free, open-source software package for linking UNIX systems toWindows file and printer sharing, and for achieving various other kinds of interoperability between networks. For details, see www.samba.org. The name is derived from SMB (Server Message Block), an important part of the protocol that Samba follows.

a protocol for viewing e-mail on a personal computer while leaving it in place on the host system. Contrast pop, which delivers the mail and deletes it from the server.

a protocol for assigning an IP address to each computer automatically as it joins the network, for use as long as it remains connected, rather than assigning a permanent IP address in advance.

1. online abbreviation for "at the moment" (i.e., now).
2. in banking, abbreviation for automatic teller machine.
3. in networking, abbreviation for Asynchronous Transfer Mode, a set of high-speed data transmission protocols. See protocol.Contrast TCP/IP;NetBEUI;IPX/SPX.

a standard way of transferring files from one computer to another on the Internet and on other TCP/IP networks. (See TCP/IP.) FTP is also the name of any of various computer programs that implement the file transfer protocol.

When you connect to a remote computer, the FTP program asks you for your user name and password. If you do not have an account on the computer that you have connected to, you can use anonymous FTP to retrieve files that are available to the general public. In that case the procedure is to give anonymous as your user name and then type your e-mail address in place of the password. Also remember to use the command binary if the file you are transferring is anything other than plain ASCII text. Figure 119 shows an example of an anonymous FTP session.

You can also retrieve files by FTP using a web browser. For example, to retrieve the file whose name is filename in directory pub/directoryname on host ftp.cdrom.com, give the URL as:
ftp://ftp.cdrom.com/pub/directoryname/filename
If you need to specify an account name and password, do this:
ftp://userid:password@zzzzz.com/directoryname/filename
Most browsers will prompt you for the password if you leave it out.

Ordinarily, FTP does notwork through certain routers and firewalls. For the solution, see passive FTP.

One of the most popular FTP sites, offering large amounts of free software, is ftp.cdrom.com.

a hypertext protocol that was used in the early 1990s, before HTTP. The name "gopher" is a pun on "go for" (i.e., go and get things).

the exchange of signals between two computers to indicate that data transmission is proceeding successfully.

a standard method of publishing information as hypertext in HTML format on the Internet. URLs (addresses) for web sites usually begin with http:.

a protocol that extends TCP/IP by adding CORBA defined messages for objects to connect to each other over the network.

the main U.S. law against wiretapping and other interception of private electronic communications, whether they are transmitted by wire, radio (including wireless network), or other means. It was passed in 1986 and superseded a number of earlier laws.

Critics point out that the ECPA does not require the sender of a message to encrypt (scramble) it to make it private. Thus, private messages can still be intercepted deliberately or even by accident. For example, first-generation analog cellular telephones were assigned to frequencies formerly occupied by UHFTV channels, and they used the same kind of modulation as TV sound. Thus, telephone calls could be picked up on old television sets. Similarly, radio technicians tracking down sources of interference could find themselves hearing things that are illegal to listen to.

On the whole, however, the ECPA is an essential part of the laws protecting computer networks and communication systems from tampering and eavesdropping. It is one of the laws most commonly violated by crackers.

version 6 of the Internet Protocol, which will provide for improvements in routing network traffic and will increase the number of available network addresses. There will be a transition period when this version will gradually replace the current version (IPv4). See www.ipv6.org.

1. Post Office Protocol, a standard protocol for delivering e-mail to personal computers.See protocol.
2. point of purchase (point of sale). For example, a POP computer is a computer used as a cash register.See point-of-sale system.
3. point of presence, a place where an Internet service provider can be accessed, such as a local telephone number.

a communications protocol often used in dial-up networking. Compare SLIP.

the transmission of voice telephone conversations through the Internet or through IP networks. Several protocols are used for this purpose.

a data transmission protocol developed by Novell and widely used in local-area networking. Contrast ATM; NetBEUI; TCP/IP.

a data transmission protocol developed by IBM and Microsoft and widely used in local-area networking. It is usually the preferred protocol for networking Windows systems but does not support routing. Contrast TCP/IP; IPX/SPX; ATM.

a protocol used to transfer electronic mail between computers on the Internet and other TCP/IP networks.

a protocol for delivering graphical images from a scanning or imaging device to application software. The name is said to stand for "technology without an interesting name".

TWAIN strives to reduce the number of device drivers needed by providing a standard communication format. For more information about TWAIN, see www.twain.org.

a protocol for transferring files from one computer to another by modem without going through the Internet. Kermit is also the name of a program (distributed free by Columbia University) that implements this protocol.

Kermit makes an exact copy of the original file even when transmitting over a noisy line. All data packets are error-checked, and erroneous packets are retransmitted.

a protocol for executing methods (procedures, functions, subroutines) on a remote computer using XML to encode the data and HTTP to perform the data transmission. SOAP can be used by COM, CORBA, and other kinds of distributed applications.

an authentication protocol that allows users and computers to identify each other without risk of impersonation and to communicate securely by encrypting their data. A Kerberos system uses a central authentication server to issue tickets, which are temporary authorizations to communicate. Each ticket is valid only for a specific user and for a limited length of time. Thus, an intercepted or stolen ticket is of little use. Because of the encryption used, forged tickets are virtually impossible to produce.

Kerberos was developed at the Massachusetts Institute of Technology, which distributes an implementation of it free of charge (http://web.mit.edu/kerberos/www/). Kerberos has many commercial implementations. See PROTOCOL. In Greek mythology, Kerberos (in Latin, Cerberus) is the dog that guards the gate of Hades.