document updated 15 years ago, on May 6, 2008

There are a number of libraries for sniffing packets.

WinPcap (usermode: windump)
Microsoft's Network Monitor Driver (usermode: netmon)
microOLAP's Packet Sniffer SDK
Raw sockets (this program is about the only one that claims to have accomplished it... how exactly did they do it though?)
- WFP callouts? (no, WFP is Vista-only, SmartSniff claims to be XP/2K compatible)