This page contains handy instructions for doing things with wireless cards on the Mac.

Airport utility

Start by creating a symlink to the airport utility, a hidden utility that comes with the Mac, somewhere on your path:

sudo ln -fs /System/Library/PrivateFrameworks/Apple80211.framework/Versions/Current/Resources/airport /usr/local/bin/airport

Now you can use the airport utility as a stand-in for the usual Linux networking utilities.

Sniff a channel

The syntax for sniffing a channel on a wireless interface is as follows.

Start by finding you wireless interface name with ifconfig. The built-in wireless is probably en1. The syntax is:

sudo airport [interface] -c [channel]