Operation Manual

Chapter 10 Network Address Translation
NBG-418N v2 User’s Guide
110
10.6 Technical Reference
The following section contains additional technical information about the NBG-418N v2 features
described in this chapter.
10.6.1 NAT Port Forwarding: Services and Port Numbers
A port forwarding set is a list of inside (behind NAT on the LAN) servers, for example, web or FTP,
that you can make accessible to the outside world even though NAT makes your whole inside
network appear as a single machine to the outside world.
Use the Application screen to forward incoming service requests to the server(s) on your local
network. You may enter a single port number or a range of port numbers to be forwarded, and the
local IP address of the desired server. The port number identifies a service; for example, web
service is on port 80 and FTP on port 21. In some cases, such as for unknown services or where one
server can support more than one service (for example both FTP and web service), it might be
better to specify a range of port numbers.
In addition to the servers for specified services, NAT supports a default server. A service request
that does not have a server explicitly designated for it is forwarded to the default server. If the
default is not defined, the service request is simply discarded.
Note: Many residential broadband ISP accounts do not allow you to run any server
processes (such as a Web or FTP server) from your location. Your ISP may
periodically check for servers and may suspend your account if it discovers any
active services at your location. If you are unsure, refer to your ISP.
Open Protocol Specify the protocol (UDP, TCP or UDP/TCP) that a server on the WAN uses when it
sends out a particular service.
Apply Click Apply to save your changes back to the NBG-418N v2.
Reset Click Reset to begin configuring this screen afresh.
Application Rules Summary
Service Name This field displays the name of the application rule.
Trigger Protocol This field displays the protocol that causes (or triggers) the NBG-418N v2 to record the IP
address of the LAN computer that sent the traffic to a server on the WAN.
Direction This field displays the direction of travel of packets that match this rule.
Match Port This field displays the port(s) that causes (or triggers) the NBG-418N v2 to record the IP
address of the LAN computer that sent the traffic to a server on the WAN.
Open Protocol This field displays the protocol a server on the WAN uses when it sends out a particular
service.
Related Port This field displays the port(s) a server on the WAN uses when it sends out a particular
service. The EMG2926-Q10A forwards the traffic with this port (or range of ports) to the
client computer on the LAN that requested the service.
Action Click Delete to remove the rule.
Table 50 Network > NAT > Port Triggering (continued)
LABEL DESCRIPTION