RawCap - http://www.netresec.com/?page=RawCap
- free command line network sniffer for Windows that uses raw sockets.
- Can sniff any interface, including WiFi and PPP interfaces, that has got an IP address, including 127.0.0.1 (localhost/loopback)
- RawCap.exe is just 17 kB
- No external libraries or DLL's needed other than .NET Framework 2.0
- No installation required, just download RawCap.exe and sniff
- Minimal memory and CPU load
- Reliable and simple to use
More info at "RawCap sniffer for Windows released"