UPnP Port Mapping Screen

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 RAID and Data Protection on page 163 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.

Figure 65 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.

Figure 66 UPnP Port Address Translation for FTP Example

In the above example, the Internet gateway uses PAT to accept Internet user FTP sessions on port

TCP: 21

TCP: 21

192.168.1.20

a.b.c.d

TCP: 2100

TCP: 21

192.168.1.20

a.b.c.d

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For example, if the NSA’s IP address was 192.168.1.33 when you applied the UPnP Port Mapping screen’s settings and the NSA later gets a new IP address of 192.168.1.34 through DHCP, WAN access stops working because the Internet gateway still tries to forward traffic to IP address 192.168.1.33. Since you can no longer access the NSA from the WAN, you would have to access the NSA from the LAN and re-apply your UPnP Port Mapping screen settings to update the Internet gateway’s UPnP port mappings.

Figure 67 UPnP Using the Wrong IP Address

8.5.2 UPnP and Security

UPnP’s automated nature makes it easier to use than manually configuring firewall and NAT rules, but it is also less secure. Using UPnP may make your network more susceptible to snooping and hacking attacks.

8.5.3 The NSA’s Services and UPnP

This section introduces the NSA’s services which an Internet gateway can use UPnP to allow access to from the Internet.

CIFS (Windows File Sharing)

Common Internet File System (CIFS) is a standard protocol supported by most operating systems in order to share files across the network. Using UPnP port mapping for CIFS allows users to connect from the Internet and use programs like Windows Explorer to access the NSA’s shares to copy files from the NSA, delete files on the NSA, or upload files to the NSA from the Internet. If you configure UPnP port mapping to allow CIFS access from the WAN but cannot get it to work, you may also have to configure the Internet gateway to also allow NetBIOS traffic. See Section 6.3 on page 141 for more on CIFS.

FTP

File Transfer Protocol is a standard file transfer service used on the Internet. Using UPnP port mapping for FTP allows remote users to use FTP from the Internet to access the NSA’s shares. A user with read and write access to a share can copy files from the share, delete files from the share, or upload files to the share. See Section 9.4 on page 177 for more on FTP. If you use UPnP to allow FTP access from the WAN, you may want to use a different WAN port number (instead of the default of port 21) to make it more secure. Remember to tell the remote users to use the custom port number when using FTP to access the NSA.

192.168.1.34

a.b.c.d

192.168.1.33

Chapter 8 Network

HTTP (Web Configurator)

You can use UPnP port mapping to allow access to the NSA’s management screens. If you use UPnP to allow web configurator access from the WAN, you may want to use a different WAN port number (instead of the default of port 80) to make it more secure. Remember to use the custom port number when accessing the NSA’s web configurator from the Internet.

HTTP (Web Published Shares)

This is the NSA’s web publishing feature that lets people access files using a web browser without having to log into the Home screens. Use UPnP port mapping to allow access to these files from the Internet without having to enter a user name or password. See Section 9.8 on page 193 for more on web publishing.

8.5.4 Configuring UPnP Port Mapping

Click Network > UPnP > Port Mapping to display the UPnP Port Mapping screen.

Use this screen to set how the Internet gateway’s UPnP feature configure’s the Internet gateway’s NAT IP address mapping and port mapping settings. These settings allow Internet users connected to the Internet gateway’s WAN interface to access services on the NSA. You can set which port Internet users need to use to access a specific service on the NSA.

Note: Some Internet gateways will delete all UPnP mappings after reboot. So if the Internet gateway reboots, you may need to use this screen again to re-apply the UPnP port mapping.

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The following table describes the labels in this screen.