LANCOM Systems Support KnowledgeBase - Support Information
Document No: 0906.0809.0653.TPOR

Port forwarding: Setting up a web- and ftp-server behind the masked connection of a LANCOM router

Description:

This document describes the settings required to be able to operate a Web server and an FTP server behind a LANCOM router.

Procedure:

Most Internet access options from Internet providers include just one IP address that can be reached direct from the Internet. LANCOM devices use a mechanism known as NAT/PAT (network address translation / port address translation) to connect an entire network to the Internet via a single public IP address. In this process, the router translates the private IP addresses of the computers in the LAN to the LANCOM's public IP address. In this case, only the public IP address can be accessed from the Internet, which in this case is directed exclusively to the LANCOM itself. This serves to shield the private network from the Internet.

If selective access is to be allowed to a server in the LAN, the connection to the server's private IP address must be configured in the LANCOMS router's configuration. For this it is important to know the address of the server port which the service is running on; for example, a Web server runs on port 80 by default. You can find a complete overview of registered ports (so-called well-known ports) on the IANA (Internet Assigned Numbers Authority) Web site, which is responsible for allocating protocol and port numbers in the Internet. You can access the complete overview of port numbers under this link:

http://www.iana.org/assignments/port-numbers


1. In LANconfig, open the configuration dialog for the LANCOM router and go to the menu Configuration -> IP router -> Masquerading.

2. Click on the Port forwarding table button.



3. Click on Add to create a new entry for port forwarding.



4. Into the two fields first port and last port, enter port 80.

5. As remote site, select the remote site for the Internet connection. If no remote site is specified, port forwarding will apply globally for all Internet connections.

6. In the Intranet address field enter the local address of the designated web server.

7. Under Protocol you can choose whether forwarding is to apply to TCP or to UDP connections, or both.



Information:
    • Under Map port you can specify a target port for remapping the port addressed from the Internet. If the port is to remain 80, as in our example, nothing has to be entered here.
    • WAN address allows you to specify a WAN address for which the port mapping should apply. This is particularly relevant when more than one public IP address is available on a WAN connection.If you choose not to use this, leave this value set to 0.0.0.0. In our example we have only one public IP address, so the field remains unchanged.

8. Store your entries with OK.

9. Now you set up the port forwarding for the FTP server. Configure this entry as illustrated in the figure below.



Note:
  • The LANCOM WEBconfig service works like any other Web server on port 80. If you activate a Web server in the LAN via the service table as described in the example, you can still access the LANCOM router's WEBconfig Interface from the Internet using port 8080 or using HTTPS protocol.
  • It is also possible to modify the http port in the LANCOM device.