RawCap is a free command line network sniffer for Windows that uses raw sockets.

Quick RawCap facts:

• Can sniff any interface that has got an IPv4 address, including 127.0.0.1 (localhost/loopback)
• RawCap.exe is just 48 kB
• No external libraries or DLL's needed other than.NET Framework
• No installation required, just download RawCap.exe and sniff
• Captures from any type of network, including WiFi, VPN, WWAN (Mobile Broadband) and PPP interfaces
• Simple to use