Technical Reference; Nat Port Forwarding: Services And Port Numbers - ZyXEL Communications LTE3301-M209 User Manual

To enable and disable the SIP ALG in the Zyxel Device, click Network > NAT > ALG. The screen appears
as shown.
Figure 61 Network > NAT > ALG
The following table describes the labels in this screen.
Table 41 Network > NAT > ALG
LABEL
ALG-SIP
Apply
Cancel

10.6 Technical Reference

The following section contains additional technical information about the Zyxel Device 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 Port Forwarding 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.
Chapter 10 NAT
DESCRIPTION
Select Enable to make sure SIP (VoIP) works correctly with port-forwarding and address-
mapping rules. Otherwise, select Disable to turn off the SIP ALG.
Click Apply to save your changes.
Click Cancel to begin configuring this screen afresh.
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