User's Manual

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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 Tunneling Protocol (PPtP) is a technology for creating a Virtual Private Network
(
VPN) within the Point-to-Point Protocol (PPP). It is used to make sure 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.
PSK
Pre-Shared Key (PSK), see
Shared Key.
Public Key
A public key is used in public key cryptography to encrypt a message which can only be
decrypted with the recipient's private or secret key. Public key encryption is also called
asymmetric encryption, because it uses two keys, or Diffie-Hellman encryption. Also see
Shared Key.