TCP Port Toolkit is a protocol, data, and timing analyzer.
B&W Port Scanner is a program that will scan your TCP ports.
List available hosts, open ports, and their characteristics.
Named Pipe TCP Proxy - utility which provides access to named pipes on Windows.
Serial Port Software
Serial Port Splitter grants simultaneous access to a COM port from several apps.
SkPortScan ActiveX Control is a flexible and powerful port scanner control.
HW Virtual Serial Port allows creating virual serial port drivers.
The dialer uses one local UDP port and one local TCP port.
NetworkActiv AUTAPF is a UDP and TCP port forwarder.
A multi-threaded and fast TCP port scanner.
A powerful connect-based TCP port scanner, pinger and hostname resolver. Multithreaded and asynchron....
Send an ICMP packet (ping) to a device, connect to a required TCP port.
This tool is handy if you encountered unexpected TCP port conflict exceptions.
Flachmann & Heggelbacher
Establishes TCP connections, accepts a TCP connection on a local port, etc.
TCP/IP port redirector with many features for the advanced user.
Knocker is a simple and easy to use TCP security port scanner.
Coral Works, Inc.
Software-based TCP/IP port forwarder and network administration service.