On UPnP and NAT (Network Address Translation)

Question

Why UPnP is an often asked Question.
This article goes a long way to say why.
A couple of Quotes
*What is UPnP?*
Universal Plug and Play (UPnP) is an architecture for pervasive peer-to-peer network connectivity of PCs and intelligent devices or appliances, particularly within the home. UPnP builds on Internet standards and technologies, such as TCP/IP, HTTP, and XML, to enable these devices to automatically connect with one another and work together to make networking - particularly home networking - possible for more people.
*Are there other ways to solve the problem of NAT traversal? If so, why is using UPnP the best choice?*
Yes, there are other ways to solve this problem, but no other mechanism currently exists as an industry standard to address this problem in an automatic way for the consumer and in such a universally-applicable way for the developer.
Simply Automated Starter Package
Other approaches require either manual intervention by the user or they require special development efforts by the Internet gateway device vendor and the software developer to handle the NAT traversal needs of specific applications. As a result, UPnP is uniquely able to solve this important problem.
*Consumer does the work.* The manual intervention methods of NAT traversal require a consumer to use a browser, a graphical user interface-based tool on the PC, or a command line interface tool on the PC to change some settings on the Internet gateway device in the home. While some technical enthusiast users have little difficulty with this, many consumers do not feel comfortable doing this. Further, many consumers may not even realize that NAT traversal problems are interfering with their use of services across the Internet. _The user may be attempting to play a multi-player game or engage in some other peer-to-peer service but find he or she cannot connect for some reason._ This leads to troubleshooting, support calls, customer dissatisfaction, and reluctance on the part of the user to try new services or experiences in the future.
*Developer does the work.* To avoid requiring the consumer to solve this NAT traversal problem manually, some Internet gateway device vendors have written and included application layer gateway support into their devices. This application layer gateway software is designed with specific applications in mind. In other words, the device vendor writes and tests specific code that will automatically enable one application to go through the NAT. If the application software is updated, the application layer code the device vendor wrote may have to be updated and tested again. This one-at-a-time way of chasing the NAT traversal problem is manageable for device vendors when there are only a few peer-to-peer or relevant applications to consider, but this approach does not scale well to 100s or 1000s of applications, can be very expensive to pursue, and likely requires specific knowledge of how each of these applications function. The better way to approach this problem is to have the device vendor add software or firmware to their device once to understand UPnP and have other devices and software be able to communicate with the NAT device using this same technology. UPnP is uniquely able to fulfill this role today.
I have underlined a passage in the last.
I hope this helps in some way.
6:58 PM Tuesday; January 1, 2008

Answer 1

          Look for bindAddr in the weblogic.properties doc.
          weblogic.system.bindAddr
          You can use a dns name instead of an ip address
          Mike
          David Chen <[email protected]> wrote:
          >We are planning to add a client that needs to access our weblogic cluster
          >through firewalls with IP address translation. According to the WebLogic
          >(5.1) documentation, this could be done by opening port 7001 in the
          >firewalls, and BIND WebLogic SERVER INSTANCES TO DNS NAMES. Does anyone
          >know how to bind WebLogic server instances to DNS names? Should it be
          >done in weblogic.properties?Thanks in advance,David [email protected]