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APPENDIX C: Glossary
back to me at this IP address." In essence, it appears as though all your clients
requests are coming from that one IP address (hence the name "IP
masquerading"). When all the information comes back through the Broadband, it
sorts the data using an Address Translation Table and returns the data to the
computer on your network that requested it.
If someone on the Internet tries to access your network, the firewall function of the
Router stops the request. The device will not reverse-translate network addresses
unless you have specifically allowed this feature using the Virtual Server function
(IP Mapping).
Network Address: The network portion of an IP address. For a class A network, the
network address is the first byte of the IP address. For a class B network, the
network address is the first two bytes of the IP address. For a class C network, the
network address is the first three bytes of the IP address. In each case, the
remainder is the host address. In the Internet, assigned network addresses are
globally unique.
P
Packet: A packet is a piece of a message transmitted over a packet-switching
network. A packet contains the destination address of the message as well as the
data. In IP networks, packets are often called datagrams.
Port Number: The term "port" can mean the connector on your computer or it
can be thought of as a server number. Every service that travels over phone lines
and modems has a standard port number. For example, the World Wide Web
service uses the standard port number, 80; the standard telnet port is 23.
Port numbers are controlled and assigned by the IANA (Internet Assigned
Numbers Authority). Most computers have a table in their systems containing a list
of ports that have been assigned to specific services. You can also find lists of
standard port numbers on the World Wide Web.
PPP (Point-to-Point Protocol): PPP enables dial-up connections to the Internet and
is the method that your network device connects to the Internet. PPP is more
stable than the older SLIP protocol and provides error-checking features.
Protocol: A formal description of message formats and the rules two computers
must follow to exchange those messages. You can think of protocols like
languages. If two computers or devices aren't speaking the same language to each
other, they won't be able to communicate.
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