Basics On Rednet?

I've been using ComputerCraft with the latest TechnicPack and Tekkit, and me and my friend are trying to connect the computers using rednet. I've connected two computers using bundled cables (though I've tried regular alloy too).

I've done on computer one

rednet.open("back")
rednet.broadcast("Ohai!")

Then on computer two

rednet.open("right")
message = rednet.receive(20)
print(message)

I start the receive on computer 2 first and then broadcast.

But when I print the message, I get a 1. (And the broadcast returns true)

Please help!

id, message = rednet.receive(20)

You're quick!! Thank you! I've noticed that it adds a "1" at the end. What is that for?

Edit: That's only when you run it from the lua interpreter.