Networks and Software

Just about all networks (particularly home networks) these days are set up using ethernet for the hardware portion and tcp/ip for the communications layer. You would expect therefore that any device that supports those protocols should be able to be connected to your network and will then work.

Well that much is true. Provided that you can assign the device an IP address recognised on your network then the device will be accessible as a part of your network.That doesn't however mean that any software that you install (or which comes pre-installed) on the device is going to work with your network because that depends on how your network is configured. Of course any software designed to run on a tcp/ip network should operate with your network provided that you can configure your network the right way.

One area where you may need to make configuration changes to get software to work is the security software that you have running. If the software uses a particular communication port within TCP/IP then that port needs to be open on the devices within your network in order for the software to be able to communicate between those devices. If the software needs to be able to communicate with the internet then that port also needs to be open in your router (possibly using IP forwarding for that port so that the router knows which device on your network to direct the requests on that port to so that they can be processed by that software.

There are two different situations to consider with regard to software and networks and the configuration issues are different for each. Networked software works with software running on both of the computers that are communicating using the software with one end being the server and the other being the client. Where the software running on your end is the client software that initiates a request to the server and expects to receive a response then the configuration required should be simply a matter of making sure that your firewall is set up so as to give the program permission to send requests and receive responses to those requests. Where the software running on your end is the server then you need to have your network configured so as to be able to receive requests. For your network to be able to receive requests the appropriate port on which those requests are made needs to be open on the device where the software is installed and the router needs to be configured to forward requests on that port to the appropriate device.

So for example if you are running a web server on one computer (or other device) on your network that you want to be accessible to the other computers on your network then the firewalls on the computer where the web server is running needs to have port 80 (and possibly port 443) open in order for your computers to see that web server. If you also want the web server visible from the internet you need to configure your router to forward requests on port 80 to that computer. The same applies to any other server service that you are running on your network.

The problem comes where you have software where you need ports open for the software to function and you don't know what those ports are. Unless you can find out what port or ports need to be open in order for certain software to function on your network you are never going to get that software to work. If the software uses a standard protocol for its communications then determining which ports to have open is simply a matter of determining what protocol is being used and looking up what port that protocol uses. The big problem is software that uses a proprietary protocol. In that instance unless the software owners identify what port their software uses you are not going to be able to configure your router so that the software can work.

Most people with home networks do not normally change the settings in their router. In most instances there is no need to. Not all routers though have the same settings as their default and so software that will work without any problems on a network using one particular router may be quite unusable on a netowrk using a different router where the default router settings are different. To at least some extent this depends on the level of security built into the router itself. The Netcomm router that I am using appears to have the security settings in the router at a somewhat higher level than many other routers do as I have come across a number of situations where it blocks software from working that is known to work without any issues on other networks. One example of this was when we connected an xbox to the network and attempted to connect through to xbox live. For this to work two changes to the router settings were required. The first was explained clearly in the error message where it specified that upnp needed to be enabled in the router. The second was that the xbox port was blocked. Information on Microsoft's web site identifies which port this is so that the router can be configured to forward all requests on that port to the xbox and even with the port blocked it just prevented the xbox acting as the server for certain options and didn't affect most of the functioning.


This article written by Stephen Chapman, Felgall Pty Ltd.

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