WinPCap
WinPcap is a port of the Unix libpcap (packet capture) library, which in turn is build on BPF (Berkeley Packet Filter). WinPcap consists of wpcap.dll, which implements the high-level functions, and packet.dll, which is the kernel-mode driver.
Snort (www.snort.org) and Ethereal (www.ethereal.com) both use WinPcap.
WinPCap
A piece of shit program that is capable of bringing down all network traffic when run under Windows XP
Damn, this generic program is nearly as bad as WinPCap