The Null-modem emulator (com0com) is a kernel-mode virtual serial port driver for Windows. You can create an unlimited number of virtual COM port pairs and use any pair to connect one COM port based application to another. The HUB for communications (hub4com) allows to receive data and signals from one COM or TCP port, modify and send it to a number of other COM or TCP ports and vice versa.
tcp2com creates a bridge between a TCP socket and a serial port (COM). The program runs as a service under Windows NT. With tcp2com, you can telnet into any device you may have plugged into your COM port.