Since its inception in 2001, Dynamic Network Services offers a fantastic service called DynDNS. This is a Domain Name Service (DNS) that you can freely use. The company is quite popular in their line of work, so a number of routers have DynDNS service implemented in their software. I have been using this for a year or so in my Canyon WLAN Router and it works flawlessly.

For those who are still wondering what am I talking about, DynDNS can be used for giving your IP address a good-looking hostname. This is especially useful in situations where you are using dial-up access or ADSL connections with dynamic IP addresses. By using the DynDNS service with a combination of their software installed on your computer, you can be always available through the same host name. You can use this setup when you are hosting a web server on your local computer or when you want to use service like Virtual Network Computer (VNC) to access your desktop from a far away location. In both of these scenarios, you will need a static address, so the DynDNS service comes quite handy.

First you need to visit the DynDNS web site and create an account. One of their policies is that one person cannot create multiple free accounts, so watch out for this. When signing up, you will receive an e-mail requesting you to confirm the registration process.

After this you can log into your account. You will see a lot of options but don't bother with them, on the bottom there is a link saying "Add Host Services". Follow this link and then click on "Add Dynamic DNS Host". Here you will be able to chose your own hostname. There are tens of domains you can use and for the purpose of this article I chose nonstopmac.blogdns.com. The default IP you will se in the settings will be your current IP. In 99% of the times this is the IP to use, as you want hostname to resolve to the computer you are currently using. After setting this up click "Add host" and you are finished with the "first and only time" web setup.

I mentioned that the DynDNS service needs locally installed software. This is because the best way to alert their service that you have a new IP address is by doing it automatically. Manual labor is both boring, time consuming and in some cases inefficient (some ADSL lines are made to change the IP address transparently). The software consists of two parts - a daemon listener and a widget. Of course the daemon is more important, so you will be able to use it on non-Tiger Macs.

The configuration is pretty straightforward: you need to "Add user" by filling in username, password and description fields. Of course you need to use the account credentials you have setup for the DynDNS service. Now the software will snatch your information from the online account. If in any case IP address or a hostname you are using don't pop-up in the list, use "Edit hosts" to manually write in the details (btw, be sure to chose the Dynamic DNS option).

Now, the most important thing is that the IP you are seeing is the right one - you will need to change to the Interface you are using. Depending on the type of your connection there are a couple of options. Chose:

Default Interface

- If you are connected through normal modem, you should chose Default Interface

External Interface

- If you are connected to the Internet via ADSL modem, ADSL router, WLAN ADSL router and similar devices

Bottom line - the IP that will show on activated connection must be your external one - if it starts with something like 192.168.X.X, you can be sure that it is wrong (this subnet is used for local IP addressing).

After setting all of the information, just watch out that your daemon is running (there is a Pause button on the bottom of the File -> Edit Users screen that toggles this option on and off. Also a very important thing is that the "Active" boxes in the "Edit users" screen are checked on!

To test everything works just fine, you can ping the hostname. Pinging it will show the IP the domain currently resolves:

[bk@romero local]$ ping nonstopmac.blogdns.com
PING nonstopmac.blogdns.com (83.131.3.36) 56(84) bytes of data

Needless to say that the daemon must run in the background to be able to report your new IP address to the DynDNS service. File -> Preferences holds information on the daemon behavior on system boot-up.

Finally I would like to mention the DynDNS widget. It is just an eye-candy application showing the current state of your hostname and IP address. You can also change interfaces from inside this widget.

So this is basically it, if you have followed these instructions everything should work just fine.