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Glossary
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Packet Filter A filter that scans packets and decides whether to let them through.
PAP Password Authentication Protocol PAP is a security protocol that requires users to
enter a password before accessing a secure system. The user’s name and password
are sent over the wire to a server, where they are compared with a database of user
account names and passwords. This technique is vulnerable to wiretapping
(eavesdropping) because the password can be captured and used by someone to log
onto the system.
POP Post Office Protocol. This is a common protocol used for sending, receiving, and
delivering mail messages.
POTS Plain Old Telephone Service is the analog telephone service that runs over copper
twisted-pair wires and is based on the original Bell telephone system. Twisted-pair
wires connect homes and businesses to a neighborhood central office. This is called
the local loop. The central office is connected to other central offices and long-distance
facilities.
PPP Point to Point Protocol. PPP encapsulates and transmits IP (Internet Protocol)
datagrams over serial point-to-point links. PPP works with other protocols such as IPX
(Internetwork Packet Exchange). The protocol is defined in IETF (Internet Engineering
Task Force) RFC 1661 through 1663. PPP provides router-to-router, host-to-router,
and host-to-host connections.
Protocol A “language” for communicating on a network. Protocols are sets of standards or rules
used to define, format, and transmit data across a network. There are many different
protocols used on networks. For example, most web pages are transmitted using the
HTTP protocol.
Proxy Server A server that performs network operations in lieu of other systems on the network.
Proxy Servers are most often used as part of a firewall to mask the identity of users
inside a corporate network yet still provide access to the Internet. When a user
connects to a proxy server, via a web browser or other networked application, he
submits commands to the proxy server. The server then submits those same
commands to the Internet, yet without revealing any information about the system that
originally requested the information. Proxy servers are an ideal way to also have all
users on a corporate network channel through one point for all external
communications. Proxy servers can be configured to block certain kinds of connections
and stop some hacks.
PSTN Public Switched Telephone Network was put into place many years ago as a voice
telephone call-switching system. The system transmits voice calls as analog signals
across copper twisted cables from homes and businesses to neighborhood COs
(central offices); this is often called the local loop. The PSTN is a circuit-switched
system, meaning that an end-to-end private circuit is established between caller and
callee.