Crestron
e-Control
®
Software
•
The Registered Ports are those from 1024 through 49151—Crestron has four
registered ports for CIP and TCP communication.
•
The Dynamic and/or Private Ports are those from 49152 through 65535.
Some examples of well-known port numbers are FTP (port 21), Telnet (port 23),
E-mail (SMTP, or Simple Mail Transfer Protocol, port 25) and WWW (port 80).
If the server machine accepts connections on a port from the outside world, and if a
firewall is not protecting the port, you can connect to the port from anywhere on the
Internet and use the service.
Note that nothing forces a Web server, for example, to be on port 80. If you were to
set up your own Web server, you could put it on port 49153 or any other unused port.
Then if the server were located at
http://www.e-control.com
, someone on the
Internet could connect to that server by typing
http://www.e-control.com:49153
":49153" explicitly specifies the port number, and would have to be included for
someone to reach the server. When no port is specified, the browser simply assumes
that the server is using the well-known port 80.
Port Mapping
If a firewall or NAT is protecting a port, an Internet client can still access a server
machine on the internal LAN if the router or NAT is configured for
port mapping
.
Port mapping is a mechanism that makes specific services available to the WAN
without exposing other areas of the internal LAN.
Here you assign an “external” port number to whichever service you want to make
available to the outside world; the external port is mapped to the real port number on
the internal LAN. This allows anyone on the outside to connect to the server, if they
know the IP address or domain name address of the router and the external port
number of the server.
For example, if you were to set up a Web server on the internal LAN, you could
assign it an external port number 918, and map it to internal port 80. Any Internet
client that wants to connect to that server would then need to know the IP address of
the router, and the external port number. If the router were located at IP address
195.164.35.7, the client would enter http://195.164.35.7:918, as shown below.
Router Port Mapping Settings
External Port IP Address Protocol Internal Port
918 192.168.1.8 TCP
80
Server (192.168.1.8)
Browser (http://195.164.35.7:918)
LAN (192.168.1.1)
Router
WAN (195.164.35.7)
Hub
Most routers allow between 10 and 16 ports to be opened using port mapping; the
Crestron NAT that is built into the 2-Series processor allows up to 16.
Reference Guide – DOC. 6052
Crestron e-Control®
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