How Mac OS X’s “Internet Sharing” Saved My Vacation
So I am on vacation right now and the unthinkable happened after we checked into our place: there was NO wifi available. The hotel didn’t have wifi available at all (welcome to 1990). No coffee shops or residences in the area where I could see their network. Not a thing.
Luckily my dad has a Sprint EVDO card that he uses to get online with his MacBook, but I didn’t want to have to depend on using his computer during our whole trip. I got to thinking about how we could share his connection and immediately fired up the “Internet Sharing” functionality that is available in Mac OS X.
I flipped open the “Internet Sharing” preference pane, selected to share his EVDO connection through Airport and immediately went to my machine. I saw the new network that was created, immediately connected to the network (thinking “how easy was this?) and… nothing.
I went back into the Network Preference Pane on my computer and saw that while I was connected to my dad’s “Airport Network”, I was not getting a real IP address (getting one of those nasty 169.x.x.x self-assigned addresses). Those are no fun to deal with ever and was thinking “now what?”.
After poking around the network configuration on my dad’s computer, I finally saw that he too had a self-assigned IP address for his Airport. It turns out that the Sprint EVDO card actually uses PPP to connect and there’s no real place to specify an IP address. I decided to flip back to the configuration of his Airport and give him a hard-coded IP address (opting with the ever popular 192.168.1.1). From there I went back to my computer and gave myself a hard-coded IP address (going with the next logical address of 192.168.1.2). I added my dad’s IP of 192.168.1.1 for the Router field within the preference pane and then… nothing.
So now I was getting frustrated and just out of pure frustration, I fired up Terminal and tried to ping my dad’s computer. No problems… Ok, cool. Now for kicks I decided to ping the IP address of the Router that gets populated when he connects through EVDO. Guess what? I was hitting it! It was all coming together now. I had Internet connectivity, I just didn’t have any DNS configured.
I quickly fired up OpenDNS.com (on my dad’s computer, remember I still couldn’t resolve URLs), got the two OpenDNS DNS addresses (208.67.222.222 and 208.67.220.220 for those keeping score at home), applied my Network changes and the rest was history.
I know this is a long story but I wanted to put this out here for two reasons…
1.) I wanted to make sure that I put this somewhere so if I ever have to do it again, I’ll remember how to set things up.
2.) Just to prove how great the Mac OS is. I don’t think there’d be anyway to do this on Windows… If there is, I’d love to know. :)

May 21st, 2008 at 12:59 pm
In windows you just turn on ICS (Internet Connection Sharing) on the host and then just route right through that box.
May 26th, 2008 at 9:04 am
I don’t believe you. :)