A simple libpcap example for live packet captures

libpcap is an extremely useful library for, among other things, capturing network packets in realtime. The library has a lot of options, so I put together a simple example of how to do a packet capture. Depending on your platform, libpcap may return packets in "chunks". In other words, the kernel may wait until a certain number of packets have been received, or a certain amount of time has elapsed, before notifying your application that data is available. In this example, since I want to be notified as soon as a packet is available, I attempt to turn off those behaviors using the pcap_set_timeout() and pcap_set_immediate_mode() APIs. These APIs may behave differently across various platforms.