Not sure where to post this so I'll start here.

I need one machine inside a firewall to access another machine inside another firewall! I have no access to the firewalls.

One thought that comes to mind would be a machine that sits outside the firewalls which both could access. It could then use socat or something to link the two. Is there a service/site available to do this???

Specifically I need computer A (behind it's firewall) to access the serial port of computer B (behind yet another firewall). I've been able to use socat to link the listening port on computer B to one of it's comports. Now I need to be able to have computer A connect to the listening port on computer B. I've been able to test this within a network and it works fine. The next step is to work across the firewalls.

Any help or direction is GREATLY appreciated.