Create a virtual serial port and publish it on TCP port:
socat pty,link=/dev/virtualcom0,rawer tcp-listen:2101
In another computer, for instance, another virtual port can be created and connected to the previous one:
socat pty,link=/dev/virtualcom0,rawer tcp:SERVER_IP:2101
If in any of those both sides we want to open a real serial port, for instance, in the server case we can run:
socat /dev/ttyS0,rawer tcp-listen:2101
More information on socat manpage.