Workshop

applications and protocols are based on the client/server model.
CNE
Certified Novell Engineer.
COM port
A serial communications port, sometimes used to connect modems (and even mice).
common carrier
Any government-regulated utility that provides the public with communications (for example, a
telephone company).
common gateway interface (CGI)
A standard that specifies programming techniques through which you pass data from Web servers
to Web clients. (CGI is language neutral. You can write CGI programs in Perl, C, C++, Python,
Visual Basic, and many other programming languages.)
compression
The technique of reducing data size for the purposes of maximizing resource utilization (for
example, bandwidth or disk space). The smaller the data, the less bandwidth or disk space you
need for it.
Computer Emergency Response Team (CERT)
A security organization that acts to disseminate information about security fixes and assists
victims of cracker attacks. Find out more about CERT at http://www.cert.org.
copy access
When a user has copy access, it means that he or she has privileges to copy a particular file.
cracker
Someone who, with malicious intent, unlawfully breaches security of computer systems or
software. Some folks say hacker when they actually mean cracker.
CSMA/CA
See Carrier Sense Multiple Access with Collision Avoidance.
CSMA/CD
See Carrier Sense Multiple Access with Collision Detection.
DAC
See discretionary access control.
Data Encryption Standard (DES)
An encryption standard from IBM, developed in 1974 and published in 1977. DES is the U.S.
government standard for encrypting nonclassified data.
data link layer
Layer 2 of the OSI reference model. This layer defines the rules for sending and receiving
information between network devices.
datagram
A packet. RFC 1594 describes a datagram as “a self-contained, independent entity of data carrying
sufficient information to be routed from the source to the destination computer without reliance on
earlier exchanges between this source and destination computer and the transporting network.”
DECnet
An antiquated proprietary protocol from Digital Equipment Corporation that runs chiefly over
proprietary, Ethernet, and X.25 networks.