Many Central Station owners have absolutely no knowledge of IP networking and this tutorial discusses the very basics of IP addressing. It explains different ways to find out the IP address of a network device or computer so that you can take your first steps towards becoming an IP Savvy Monitoring Company without a requirement for employing dedicated I.T. staff.
Move into the world of IP at a pace that suits you!
At the heart of your IP enabled network is your modem & router. You may have heard the terms "modem" and "router" used interchangeably and you would be forgiven for thinking that a modem is the same as a router. In fact they are often sold as a single product known as a combined Modem/Router. Although it is not essential to have an in-depth knowledge of either device, it is important to understand that they are different.
A modem is responsible for negotiating and maintaining a connection to the internet via your service provider network. This could be DSL, cable, WiMax or any other technology, but as far as a network device is concerned, there is no difference between them. A router provides a number of ports that allow several computers or network devices to connect together and share one internet connection. The router connects to the modem and depends on it for an Internet connection.
Now that we understand a little about the modem & router, let's look at what happens when you connect a network enabled device or computer to your router.
Every computer or device on a network requires an IP address in order for it to function correctly and be visible to other devices on the network. So just where does your device get this IP address from?
Well, it's the job of your router to provide IP addresses to each device that forms part of your network. It uses a technology known as DHCP which dynamically allocates an IP address to each device as it is plugged into a spare port. Your router itself will have a default IP address and although 192.168.0.1 is probably the most common, it could be easily be something different.
If your router address is 192.168.0.1, the first device you plug into a port on your router will probably be allocated an IP address of 192.168.0.2, the second will be allocated 192.168.0.3 and so on. This allows you to make a good guess at what the IP address of a particular device may be, but there are other ways to find out.
On a Microsoft Windows PC, the old fashioned way is to go to the MSDOS Command Prompt, type ipconfig on the command line and press the enter key. The black screen will then display some information about the network settings on your computer and the two that are of interest to you are:
IPv4 Address - the IP address of your computer
Default Gateway - the IP address of your router
The more modern way to find the same information is by checking your network settings from within Windows. Unfortunately, Microsoft have changed the way this is done in every version of Windows and it can be an ordeal finding the settings for your network card. Once you do manage to locate the settings on your particular version of Windows, go into the properties of your network card and you will see the IP address of your computer and router.
On some network devices like the Linksys VoIP adapters used as part of the Linksys Alarm Monitoring solution, you can find out the IP address from the built-in IVR.
The IP addresses that we have mentioned so far are what we call internal IP addresses and they are only useful within the internal confines of your local network. You may have heard of external IP addresses, sometimes referred to as public - so what are they and how are they different from an internal IP address?
An external IP address is required to connect your network to the Internet. An external IP address will be allocated to your modem as it negotiates a connection with your Internet service provider. The external IP address of your modem is visible to every computer on the Internet, which is great for accessing all the resources that the Internet has to offer, but how do you prevent the undesirables out on the Internet from gaining access to your private resources?
This is your router's job and it uses a combination of technologies and techniques behind the scenes to prevent this from happening.
There are a couple of different ways to find out what your external IP address is. One way is to log into the web interface of your modem/router and look through the WAN settings. You will need to know your ID & password to get into your modem/router and the internal settings can often be quite daunting to an inexperienced user, so a much simpler way is to browse to a web site that is able to display your external IP address.
One such web site is whatismyip.com and it just so happens that it has a FAQ section about IP addresses which you can use to build on what you have learned from this tutorial.