Connecting PCs and Macs via Infrared Communications?

Stuee asks: "Isn't it about time my friend and I could sit opposite each other on the train and share documents or images without having to build a small network?! I mean, what's the point of both systems having infrared, and software to bridge the platform gap, if we can't connect? It's so frustrating that my XP laptop reports that my friend's iBook is in range, but cannot do anything about it, especially when my phone (which was a fraction of the cost of either laptop) and pocket device can communicate with both machines without any problem! If anyone knows of a workaround for this (other than cables), I think there would be a lot of people interested in hearing about it. Thanks for listening."

Comments

Re:Solution

[Twirlip of the Mists]

I just got a laptop a few months ago. I don't remember seeing a single one WITHOUT ethernet in my shopping.

I hope you're right. A former coworker of mine bought a Compaq about nine months ago-- don't know the model number-- that came without Ethernet. I hope the various PC laptop makers have come to the realization by now that Ethernet is important enough to build in.

Why would they be using the 169.254 subnet? I thought it would be 192.168 or 172.mumblemumble or 10.x.x.x subnets?

If you set your computer to get its IP info from DHCP, and no DHCP server is available, the computer will fall back to a self-assigned IP address. To self-assign, the machine picks a random address in 169.254, sends out a broadcast packet-- ARP, I think-- to see if anybody else on the local segment is using that address, repeats if necessary, and finally assigns the address to itself. All self-assigned addresses are in the 169.254.0.0/16 network. This is covered by an RFC, but I'm too lazy to look up which one.

This is also, incidentally, one of the foundations of Rendezvous. Rendezvous (a.k.a. ZeroConf) adds something called the multicast DNS resolver, which allows computers with self-assigned link-local addresses to refer to each other by name. Computer A sends out a multicast DNS packet asking for the IP address of the computer named "foo.local." Computer B is named "foo.local," so it responds with its own self-assigned IP. Computer A now knows what Computer B's IP address is, so they can communicate.

Until all the world is Rendezvous, you'll need to ask your friend what his IP address is before you can FTP (or whatever) to his machine. But you don't have to worry about assigning IPs to your machines or anything silly like that.

to show how 733+ this guy and his buddy are

Um... no offense, but do you maybe mean "1337"? ;-)