SmartFlex
tween computer systems over packet-switched,
variable-latency data networks.
OpenVPN OpenVPN implements virtual pri-
vate network (VPN) techniques for creating se-
cure point-to-point or site-to-site connections. It
is possible to create four different tunnels.
PAT Port and Address Translation (PAT) or Net-
work Address Port Translation (NAPT) see NAT.
Port In computer networking, a Port is an
application-specific or process-specific software
construct serving as a communications endpoint
in a computer’s host operating system. A port is
associated with an IP address of the host, as
well as the type of protocol used for communi-
cation. The purpose of ports is to uniquely iden-
tify different applications or processes running
on a single computer and thereby enable them
to share a single physical connection to a packet-
switched network like the Internet.
PPTP The Point-to-Point Tunneling Protocol
(PPTP) is a tunneling protocol that operates at
the Data Link Layer (Layer 2) of the OSI Ref-
erence Model. PPTP is a proprietary technique
that encapsulates Point-to-Point Protocol (PPP)
frames in Internet Protocol (IP) packets using
the Generic Routing Encapsulation (GRE) pro-
tocol. Packet filters provide access control, end-
to-end and server-to-server.
RADIUS Remote Authentication Dial-In User
Service (RADIUS) is a networking protocol that
provides centralized Authentication, Authoriza-
tion, and Accounting (AAA or Triple A) manage-
ment for users who connect and use a network
service. Because of the broad support and the
ubiquitous nature of the RADIUS protocol, it is
often used by ISPs and enterprises to manage
access to the Internet or internal networks, wire-
less networks, and integrated e-mail services.
Root certificate In cryptography and com-
puter security, a root cer tificate is either an un-
signed public key certificate or a self-signed cer-
tificate that identifies the Root Certificate Author-
ity (CA). A root certificate is part of a public key
infrastructure scheme. The most common com-
mercial variety is based on the ITU-T X.509 stan-
dard, which normally includes a digital signature
from a certificate authority (CA).
Digital certificates are verified using a chain of
trust. The trust anchor for the digital certificate is
the Root Certificate Authority (CA). See X.509.
Router A router is a device that forwards data
packets between computer networks, creating
an overlay internetwork. A router is connected
to two or more data lines from different net-
works. When a data packet comes in one of the
lines, the router reads the address information
in the packet to determine its ultimate destina-
tion. Then, using information in its routing ta-
ble or routing policy, it directs the packet to the
next network on its journey. Routers perform the
traffic directing functions on the Internet. A data
packet is typically forwarded from one router to
another through the networks that constitute the
internetwork until it reaches its destination node.
SFTP Secure File Transfer Protocol (SFTP) is
a secure version of File Transfer Protocol (FTP),
which facilitates data access and data transfer
over a Secure Shell (SSH) data stream. It is part
of the SSH Protocol. This term is also known as
SSH File Transfer Protocol.
SMTP The SMTP (Simple Mail Transfer Proto-
col) is a standard e-mail protocol on the Internet
and part of the TCP/IP protocol suite, as defined
by IETF RFC 2821. SMTP defines the message
format and the message transfer agent (MTA),
which stores and forwards the mail. SMTP by de-
fault uses TCP port 25. The protocol for mail sub-
mission is the same, but uses port 587. SMTP
connections secured by SSL, known as SMTPS,
default to port 465.
SMTPS SMTPS (Simple Mail Transfer Protocol
Secure) refers to a method for secur ing SMTP
with transport layer security. For more informa-
tion about SMTP, see description of the SMTP.
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