<p>In this case, it is probably OK to disable the OS X firewall, as you are already being protected by the router. To disable the firewall, open System Prefs >> Sharing >> Firewall. Click Stop.
<li>Find out what your IP address is. You can find your computer's IP address by going to System Prefs >> Network, double-clicking on your connection (for instance, Built-in Ethernet), and clicking the TCP/IP tab. It's probably something like 192.168.1.100, or 10.0.1.2.</li>
<li>Open Transmission, go to preferences, and enter a number for the port. It is recommended you pick a random number between 49152 and 65535. Let's use 50001 for now. Then quit Transmission.</li>
<li>Go into your router configuration screen. Normally this is done via your web browser using the address <ahref="http://192.168.0.1">192.168.0.1</a> etc.
<br>NB: Apple's Airport uses an application called 'Airport Admin Utility' to configure it.</li>
<li>Find the port forwarding (sometimes called port mapping) screen. While the page will be different for each router generally you will enter something similar to the following:</li>
<p>For more comprehensive instructions specific to your router, click <ahref="http://www.portforward.com/english/routers/port_forwarding/routerindex.htm">here</a> and choose your router from the list.
