Crestron e-Control, Справочное руководство

Страница: 10 / 74

Software Crestron e-Control
®
Internet Routers
Internet security is an important consideration in networking, since any networked
device with access to the Internet is, to some degree, at risk for unauthorized access.
Fortunately, protecting a network is both inexpensive and easy. The most simple and
flexible way to build an
Internet
firewall (network
shield from unauthorized
access) is to install a piece of
hardware into the network
that already has firewall
software built into it. The
most commonly used
firewall device is an Internet
router .
An Internet router is installed
between an Internet
connection and the rest of the
network. It protects the
network by making
individual computers, control
systems, and other Ethernet
devices “invisible” to the
outside world. The only
externally recognized device is the router itself. Put another way, a router is a
network device with two sides: one side is made up of the private LAN
of PCs,
control systems, touchpanels, etc. which this reference guide sometimes calls the
“internal LAN.” The other, public side is the Internet, or the WAN. We will see that
in some applications the “public” side can also be a corporate or residential LAN,
with the “internal” side being a sub-network within that LAN.
LAN
Router
Internet
Modem
Switch
WAN
The router’s firewall (NAT, or N etwork A ddress T ranslator) protects the internal
LAN by inspecting the data coming in from the WAN port before delivery to the
final destination on the LAN port. The router inspects Internet port services like the
Web server, FTP server, or other Internet applications, and, if allowed, it will forward
the data to the appropriate PC or control system on the LAN side.
In this way, an Internet router accomplishes two separate but related tasks. First, it
protects the network from unwanted access and/or unneeded information. Second, it
routes information to the intended destination.
Crestron NAT
Crestron manufactures an Ethernet network card for its 2-Series control systems
called the C2ENET-2 card, which provides two RJ-45 Ethernet ports (labeled LAN A
and LAN B). The card works with an internal NAT on the 2-Series processor that
enables programmers to create a sub-network within a larger corporate or residential
LAN. Here the card’s LAN A port is the public side that is visible to the larger
network, while the LAN B port connects to the private, internal LAN of e-Control
devices.
6
•
Crestron e-Control® Reference Guide – DOC. 6052