Trafscrambler is an anti-sniffer/IDS NKE (Network Kernel Extension) for Mac OS X. Author tested this on x86 OS X versions 10.5.6 and 10.5.7. It should work on PPC and older releases as well.
fa6467defc5898d3d8beae8d23338a8978e1e90bd33e00f07621ebd82993a881