Workshop

lazing speeds.)
call back
Call-back systems ensure that a trusted host initiated the current connection. The host connects, a
brief exchange is had, and the connection is cut. Then the server calls back the requesting host.
Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA)
A traffic-management technique used by Ethernet. In CSMA/CA, workstations announce to the
network that they’re about to transmit data.
Carrier Sense Multiple Access with Collision Detection (CSMA/CD)
A traffic-management technique used by Ethernet. In CSMA/CD, workstations check the wire for
traffic before transmitting data.
Cast-128
An encryption algorithm that uses large keys and can be incorporated into cryptographic
applications. (You can learn more about Cast-128 by reading RFC 2144.)
CERT
See Computer Emergency Response Team.
certificate authority
A trusted third-party clearing house that issues security certificates and ensures their authenticity.
Probably the most renowned commercial certificate authority is VeriSign, which issues (among
other things) certificates for Microsoft-compatible ActiveX components. A certificate is used to
verify the identity of a server or a user on the network.
certification
Either the end result of a successful security evaluation of a product or system, or an academic
honor bestowed on those who successfully complete courses in network engineering and support.
Two of the most popular are Novell’s CNE (Certified Novell Engineer) and Microsoft’s MCSE
(Microsoft Certified System Engineer.)
CGI
See common gateway interface.
Challenge Handshake Authentication Protocol (CHAP)
A protocol (often used with PPP) that challenges users to verify their identity. If the challenge is
properly met, the user is authenticated. If not, the user is denied access. Refer to RFC 1344 for
further information.
channel
In networking, a channel is a communications path.
circuit
A connection that conducts electrical currents and, by doing so, transmits data. Also refers to a
TCP or “circuit-oriented” connection.
client
Software designed to interact with a specific server application. For example, WWW browsers
such as Netscape Communicator and Internet Explorer are WWW clients. They are specifically
designed to interact with Web or HTTP servers.
client/server model
A programming model where a single server can distribute data to many clients (the relationship
between a Web server and Web clients or browsers is a good example). Many network