Advanced IP Scanner - Advanced IP Scanner shows all network devices, gives you access to shared folders, and can even remotely switch computers off. Download it Free.
socat - socat is a relay for bidirectional data transfer between two independent data channels.
Scapy - Scapy is a powerful interactive packet manipulation program.
Komodia Relay - Free open source tool to perform TCP based session relay
Winsock Packet Editor - WPE Pro is a packet editor.
AUTAPF - Reliable TCP and UDP port forwarding for Windows.