Lightning simply zaps various packets so that the rest of the world will think your machine didn't send them or your machine won't notice that they arrived. This sort of thing is essential for debugging retransmission heuristics.

It's viewer has various switches to select which packets get zapped.

This is still pretty crude. It needs a good dose of TLC to make it really useful. I was mostly interested in making sure that the hooks it needed were working correctly.

If you want to know what's really going on, look at the code.