The beauty of RFC-2217
Recently, I was involved in a development where remote access to a serial port was required. I was doing my development with a Rabbit core and I needed to get Internet access to a serial device and to simulate a serial port on the host PC. I learned that you could use RFC-2217 which is an extension to the telnet protocol. I went to nabble to get some help but I found out nobody seemed knowledgeable about that protocol. So I did my job, and when I got it running I wrote an article for an engineers magazine. Once I get the "go" from the editor I'll let you know where it is published.
I used with quite success Fabula Tech's Serial Port Redirector which is RFC-2217 compatible, but it is not free. For a free redirector you could use HW-group's Virtual Serial Port but be warned this latter software does not handle break signal generation. The same thing applies to Digi One SP device that, although the manufacturer claims it to be RFC-2217 compatible, it is not capable of generating arbitrary-length break signals over the serial port.