Port Triggering - ZyXEL Communications P-663HN-51 User Manual

Table 24 Advanced Setup > NAT > Virtual Servers > Add (continued)
LABEL
External Port
Start
External Port
End
Protocol
Internal Port
Start
Internal Port
End
Save/Apply

7.4 Port Triggering

Some services use a dedicated range of ports on the client side and a dedicated
range of ports on the server side. With regular port forwarding you set a
forwarding port in NAT to forward a service (coming in from the server on the
WAN) to the IP address of a computer on the client side (LAN). The problem is
that port forwarding only forwards a service to a single LAN IP address. In order to
use the same service on a different LAN computer, you have to manually replace
the LAN computer's IP address in the forwarding port with another LAN
computer's IP address.
Trigger port forwarding solves this problem by allowing computers on the LAN to
dynamically take turns using the service. The ZyXEL Device records the IP address
of a LAN computer that sends traffic to the WAN to request a service with a
specific port number and protocol (a "trigger" port). When the ZyXEL Device's
WAN port receives a response with a specific port number and protocol
("incoming" port), the ZyXEL Device forwards the traffic to the LAN IP address of
the computer that sent the request. After that computer's connection for that
service closes, another computer on the LAN can use the service in the same
manner. This way you do not need to configure a new IP address each time you
want a different LAN computer to use the application.
P-663HN-51 User's Guide
Chapter 7 Network Address Translation (NAT) Screens
DESCRIPTION
Enter a port number in this field.
To forward only one port, enter the port number again in the External
Port End field.
To forward a series of ports, enter the start port number here and the end
port number in the External Port End field.
Enter a port number in this field.
To forward only one port, enter the port number again in the Start Port
field above and then enter it again in this field.
To forward a series of ports, enter the last port number in a series that
begins with the port number in the Start Port field above.
This is the underlying protocol of the traffic to which this virtual server
entry applies.
Specify the starting port the ZyXEL Device uses for the traffic that it
forwards based on this virtual server entry (or leave it the same as the
External
The ZyXEL Device automatically determines this port number.
Click this button to save the changes and have the ZyXEL Device start
using them.
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