Appendix C Glossary
Glossary Description
A
ALG （
Gateway）
Application Level Gateway (ALG) is application
translation agent that allows an application on a host in one
address realm to connect to its counterpart running on a host in
different realm transparently.
ARP（
Protocol）
Internet protocol used to map an IP address to a MAC address.
AH（Authentication Header
A security protocol that provides data authentication and
optional anti-
replay services. AH is embedded in the data to be
protected (a full IP datagram).
D
DDNS （
Name Server）
The capability of assigning
a fixed host and domain name to a
dynamic Internet IP address.
DHCP （ D
Configuration Protocol）
A protocol that automatically configure the TCP/IP parameters
for the all the PCs that are connected to a DHCP server.
DMZ（Demilitarized Zone）
A Demilitarized Zone allows one local host to be exposed to the
Internet for a special-purpose service such as Internet
or videoconferencing.
DNS（Domain Name
Server）
An Internet Server that translates the names of websites into IP
addresses.
DSL (Digital Subscriber
Line)
A technology that allows data to be sent or received
existing traditional phone lines.
E
ESP（Encapsulating
Security Payload）
Security protocol that provides data privacy
data authentication, and anti-
replay services. ESP encapsulates
the data to be protected.
F
FTP（File Transfer
Protocol）
Application protocol, part of the TCP/IP protocol stack,
transferring files between network nodes.
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