ZyXEL Communications 4.6 ユーザーズマニュアル

 Chapter 8 Network

Media Server User’s Guide

Use UPnP (Universal Plug and Play) port mapping to allow access from the WAN to services you 
select on the NSA. It is recommended that you place the NSA behind an Internet gateway firewall 
device to protect the NSA from attacks from the Internet (see 

 for firewall type suggestions). Many such Internet gateways use UPnP to simplify peer-to-peer 

network connectivity between devices. UPnP can automatically configure the Internet gateway’s 
firewall and Network Address Translation (NAT) to allow access to the NSA from the Internet.  

UPnP for FTP Access

In the above example, UPnP creates a firewall rule and NAT port forwarding mapping to send FTP 
traffic (using TCP port number 21) from the public IP address a.b.c.d to the NSA’s private IP 
address of 192.168.1.20.

Use the NSA’s UPnP Port Mapping screen to configure the UPnP settings your Internet gateway 
uses to allow access from the WAN (Internet) to services you select on the NSA. You can also set 
which port Internet users need to use in order to access a specific service on the NSA. 

Note: To use UPnP port mapping, your Internet gateway must have UPnP enabled.

If your Internet gateway supports Port Address Translation (PAT is sometimes included with a port 
forwarding feature), you can have the Internet users use a different TCP port number from the one 
the NSA uses for the service.

UPnP Port Address Translation for FTP Example

In the above example, the Internet gateway uses PAT to accept Internet user FTP sessions on port 
2100, translate them to port 21, and forward them to the NSA. 

It is recommended that the NSA use a static IP address (or a static DHCP IP address) if you will 
allow access to the NSA from the Internet. The UPnP-created NAT mappings keep the IP address 
the NSA had when you applied your settings in the UPnP Port Mapping screen. They do not 
automatically update if the NSA’s IP address changes. 

Note: WAN access stops working if the NSA’s IP address changes.