Here is a gotcha about reading tcpdump output that recent events havebeen tattooing on my forehead:

The only sure way to tell whether a packet is going to your gatewayor to something on the local network is to look at the destinationEthernet address.

To put it another way: a packet being sent to your network's gatewaydoes not have the gateway's IP address in it. Thus, reading tcpdump output without Ethernet addresses is not really telling you whether apacket was really sent to your gateway or whether

When BitTorrent receives a file, it gets the various chunks out of order, generally in a completely randomone. This presents the client with the problem of putting them inorder and in place.

I believe that historically there have been three approaches to dealwith this. The very first BitTorrent clients did it the simple way:they put every received block in its correct place by seeking to thatspot and writing the block out. The problem with this was horrible filefragmentation (resulting in terrible sequential read performance);