I didn't find a definitive guide on the forums, and the settings are quite deeply buried, so here's a how-to for the setup of a static IP address on your N900.

Also note that this guide is aimed at new N900 and maemo users. The veterans here probably already know how to do this in their sleep.

Of course, this is only for wlan connections, since the IP addresses you get from a 3G connection can wary a lot, and the ports are usually open.

I won't go into the process of the actual port forwarding on your router. There are other, router-specific guides for that. Like the ones on www.portforward.com/

So let's begin. Say you're using Transmission, for totally legal purposes of course, and you want to open the port it uses to max your downloading speed. On a Windows or Mac computer this is relatively simple, but for a new N900 user the task of finding the input boxes for the IP addresses can be difficult.

First of all, I suggest you get the IP address widget from the extras repository. It's a great help when you need to find out what IP address you are currently behind.

Connect to your preferred wlan network and write down the IP address the widget displays. Then disconnect from the network.

Then go to the menu, then settings, then scroll down to and select internet connections. In the popup, press the "connections"-button. Highlight the wlan connection you wish to set the static IP address to, and hit Edit.

Then the edit wizard appears. Just click next without changing anything until you get to the end, where the next-button is greyed-out. A new button has appeared next to it, labeled "Advanced". Tap it.

In the resulting pop-up, choose the second tab, labeled "IP addresses".

At this point you need the subnet mask and the default gateway of your router, as well as the DNS addresses of your ISP (or any other DNS addresses you wish to use. Google has recently launched some of their own). If you've done static IP addresses on your computer, you'll know how to find these out. In a nutshell: on your computer, follow the first 4 steps on any guide here: http://www.portforward.com/networking/staticip.htm.

The DNS addresses are usually visible on the support pages of your ISP, just google "DNS [ISP name here]".

When you have those, we're good to go.

First, uncheck the "Auto-retrieve IP address"-box. Then, fill in the IP address you got from the widget in the IP address field. Do the same with the subnet mask and the default gateway, as well as the primary and secondary DNS addresses.

When done, click SAVE and then Finish. Tap yourself out of the popups, and you're, well... Done!

Now you can proceed with the actual port forwarding on your router.

Happy torrenting! (Or whatever you need a static IP address for...)