OS X Journal: Dynamic domain hosting, iRock for iPod


Week 4


I found out something strange this week. Norton System Works 2.0 includes Norton Utilities 7 and Anti-Virus 8 or OS X, but only includes NU 6 and NAV 7 for OS 9. I don't get that. I guess you need to buy Norton 7 and Anti-Virus 8 separately if you want the latest version for OS 9.

Last week I mentioned I was still having problems with my SCSI CD-RW and OS X. Well, I'm not sure why, but now it's all working. Last week I updated my Adaptec SCSI card and got the latest version of Toast for OS X. The problem was my LaCie CD-RW was not seeing blank disks. Now everything works great to my extreme pleasure. Now if I could only get my scanner going...


I got my hands on one of those iRock FM transmitter devices last week. What it does is connect to the iPod's audio jack and transmits audio over a short range using FM signals. It's intended to be used in the car, letting you tune your car radio and listen to the iPod.

I had something like this a while back, but it required external power. The iRock uses 2 AAA batteries, leaving my lighter adapter open for my early warning radar system. I'm kind of curious to see how long the batteries last, but so far it works pretty well.

How it works is you hit the power button to activate it, then you can set it to transmit on one of four frequencies. It works pretty well, but I got some static while driving around town -- it seems you need to find a good spot for it to sit. To set it up, I first checked all four frequencies on my radio to find a channel not in use and with the least amount of interference. One problem I'll have is on long trips, I'll have to switch the frequencies to avoid local stations.

As an alternative, a few months ago I tried using one of those cassette tape adapters with the iPod. It sounded horrible, almost like I was listening to AM radio. The iRock sounds pretty close the iPod's quality, so long as there's good reception.

The iRock sells for about $30 at, among other places, CompUSA and Apple Store locations.

Dynamic hosting with MOSX

Last week I talked about setting up sendmail to handle local SMTP tasks. In the article I was lamenting the fact that my ISP does not have a reverse lookup for my IP address. As a result, when computers see my IP address, they can't resolve it to an actual name. This isn't really that big of a deal, but in cases like with hotmail.com, a reverse lookup is used as a security measure to make sure email is being sent from the machine that says it's sending it. It was suggested that I try using dynamic domain hosting.

For a little background, basically each computer/device on the Internet is registered with an IP address. To find that machine, you can either type in an IP address, or a domain name. The easiest way is to use a domain name, since it means a little more than a bunch of numbers. For example, you can enter to get to IGM, but a more practical way is to type insanely-great.com. The problem is, to route the traffic, the Internet needs an IP address. A domain name server holds both the domain and IP in a table, which correlates the IP address with the domain name so that when you type in insanely-great.com, it's routed to

That's all great and all, but there's a catch. To do this, you need to have a static IP address, which is an IP address that never changes. Most people with broadband Internet like cable modems or DSL have dynamic addresses. This means the address changes as often as every time the computer is rebooted. With a dynamic IP address, there's no way a name server could resolve the domain name because the IP address is always different.

Enter dynamic domain hosting. As suggested by a reader in last week's column, dyndns.org offers both free and fee dynamic domain hosting. What dyndns.org does is host it's own domain lookup tables. So say for example, if my computer was mike.dyndns.org, each time someone typed that into the Internet, they would be asking dyndns.org for my IP address. The way dyndns.org works is that it will update its domain tables each time you get on the Internet. So while your IP address may change every day, your computer can always be found on the Internet using a domain name.

There're a lot of reasons why you would want to do this. Maybe you want to be able to always remotely log into a computer, whether at work or home, or you could even host a web site or other Internet services on your home machine, provided your ISP lets you. With a $30 donation to dyndns.org, you could even use your own domain name. Pretty cool stuff.

So here's how to set this up. After you go to dyndns.org and signup, you need to go into your hostconfig file with terminal and make some changes. For our example, lets say we set up mike.dyndns.org.

sudo pico /etc/hostconfig

Set HOSTNAME to: HOSTNAME=mike.dyndns.org

Reboot the machine

When you start back up, your computer should know it's the mike machine at dyndns.org and inside terminal your command line should look like this:

[mike:~] username

Now when you load up an ftp, ssh or web client and type in mike.dyndns.org, it'll point to your Mac, plus when you send email using sendmail, in the headers it will recognize your machine as mike.dyndns.org. To keep your domain active, you'll need to either log into dyndns.org each time your IP address changes, or use their automatic utility, which is available for both Mac OS 9 and Mac OS X.

Now to take things a step further. As I mentioned, you can have dyndns.org host your own domain name. What you can do is go to your favorite domain register, mine is intuitiveisp.com, and register or transfer a domain name to the dyndns.org folks. With the donation, they'll make sure your domain name always points to your Mac.

Happy hosting!