ibookserver Setup

my How-to quest to set up a rural dialup server on an ibook g3.

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Location: Trinity County, East Texas, United States

I'm a lawyer who likes to surf the net, play music and bitch about things I can't change.

Friday, July 01, 2005

Your Own Mail Server on Your Mac! But first - DYNDNS.org

You already have a mail server on your mac - it resides in the Darwin underlayer of your computer, you know, the FreeBSD Unix layer that drives the modern macintosh computers. Fortunately, you can turn on most of what you need to operate your own mail server by accessing the prefs of the Mail.app (the Eagle Postage Stamp Icon). To serve email to folks that are not on your household or office network (intranet), you need to do a few things under the hood.

First things first - you have to have some way for people to find you on the internet. Most of us have a dynamic IP address that is assigned by your ISP when you connect. Each time you connect, the ISP gives you a new IP address. That is no good if you want folks to get to your server from afar. You could solve this by having your ISP assign you a Static IP Address - but it usually costs more than you are willing to pay. The solution is: DYNDNS, http://www.dyndns.org/, a place where you can get a subdomain name that points folks to your computer.

Let's look at my setup: I have a dialup connection that is connected to my Airport Extreme Base Station w/modem. Whenever it detects one of my computers - connected with a wireless card or through ethernet, the Base Station assigns an IP address based on my settings. I have my server computer set up to have an assigned network address as - the base station is set as The next computer to connect is - get the picture. There are ways of making sure each computer has a permanent intranet IP address, but is beyond the scope of this article. Now, when I coonect with the Base station to my ISP - it assigns a real IP address to the base station that I can use with any of my five computers. The Base acts as a router and translates anything for my server computer and sends the info request on to - my server mac. If I set up a subdomain at dyndns.org, such as: serverman.gotdns.com, the base will now send anything to my server mac if it comes from serverman.gotdns.com. All I had to do to get this free service was to register at dyndns.org, download and set up an application that lets dyndns.org know what dynamic IP my ISP has given me each time I reconnect to my ISP. THe application is called DNSupdate, and you can find it a lot of places. Once set up, DNSupdate will tell dyndns.org every 15 minutes what my IP address is, and whether or not it changed. Dyndns then tells the DNS databases all over the internet what my new IP address is whenver it tries to find serverman.gotdns.com. To recap, People can find your servers even if you have a dynamic IP assigned to you. THe way the base and your mac distinguishes which server someone wants to talk to is by the port number - each server on your computer uses a different port, ftp access is through ports 20 -21, http is reached through port 80, etc. As long as the base know your intranet IP ( - and DNSupdate is working its magic (it loads a daemon in your unix area), and you are connected to the internet, folks can get to your servers - mail, webserver, etc. It's cool to be connected!


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