nattcpproxy

It works much like a reverse ssh tunnel. One machine behind a NAT router runs this program and it connects to another instance of the program running on a proxy machine with a static IP address or a domain name directly connected to the internet. Ports on the proxy machine can then be opened and forwarded to ports on the machine behind NAT.

This can be used for accessing servers on machines behind NAT routers including web servers, IP cameras, ftp servers, and any server which uses TCP.