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Appendix D: Glossary
PID
Psion Teklogix 9160 G2 Wireless Gateway User Manual D -65
Ethernet and the 802.11 family are protocols with physical layer components.
PID
The Process Identifier (PID) is an integer used by Linux to uniquely identify a process. A
PID is returned by the
fork()
system call. It can be used by
wait()
or
kill()
to perform actions on
the given process.
Port Forwarding
Port Forwarding creates a ‘tunnel’ through a firewall, allowing users on the Internet access
to a service running on one of the computers on your LAN , for example, a Web server, an
FTP or SSH server, or other services. From the outside user’s point of view, it looks like the
service is running on the firewall.
PPP
The Point-to-Point Protocol is a standard for transmitting network layer datagrams ( IP
packets) over serial point-to-point links. PPP is designed to operate both over asynchronous
connections and bit-oriented synchronous systems.
PPPoE
Point-to-Point Protocol over Ethernet (PPPoE) is a specification for connecting the users on
a LAN to the Internet through a common broadband medium, such as a single DSL or cable
modem line.
PPtP
Point-to-Point Tunnelling Protocol (PPtP) is a technology for creating a Virtual Private
Network ( VPN ) within the Point-to-Point Protocol ( PPP ). It is used to ensure that data
transmitted from one VPN node to another are secure.
Proxy
A proxy is server located between a client application and a real server. It intercepts
requests, attempting to fulfill them itself. If it cannot, it forwards them to the real server.
Proxy servers have two main purposes: improve performance by spreading requests over
several machines and filter requests to prevent access to specific servers or services.