"Before you can use the following solutions, you must become
familiar with the concept of port forwarding. Your computer
transfers data through a wide assortment of virtual ports. Each
port is numbered and is dedicated to a specific purpose. (email
usually funnels through port 25 while web content goes through port
80, for instance) For security reasons, your router's firewall is
configured to block incoming traffic on most ports by default. If
this were not the case, any person or program (malicious or not)
would have access to your computer from the internet.
"To use a remote access solution, you must configure your router
to accept incoming connections on the port it uses. Most routers
have a web-based interface to make this process easier. Typing
http://192.168.1.1 or http://192.168.2.1 (the default gateway
address, depending on your brand and model of router) into your web
browser will probably allow you to access your router's settings.
For specific instructions on how to enable port forwarding, check
your router documentation.
"When you set up port forwarding for a specific protocol, you
are essentially configuring your router to send all incoming data
received on that port to a specific computer on your network. This
computer is essentially a gateway (no connection to the Gateway
brand name). Once you have access to the gateway system, reaching
the rest of the network is trivial."