This page will tell you how to set a router to run an outerworlds world server behind it. I'll try to keep this short and to the point . . . For a change. ;-)
Which router to use: Although there's a lot of routers out there, one of those that I found to be the easiest to configure is the Linksys BEFSX41.
Router settings: Many people will try to get you to believe that you have to set things like Port Range Forwarding and all that, but, you don't. Or, at least not with routers like the Linksys BEFSX41. First off, go to the Security part and where it says Firewall, click that, then, make sure the radio button is selected that says Firewall Protection Enabled. In the Block WAN Requests part, I recommend enabling the blockings for anonymous Internet requests and port 113. Also, change your password! You can do that under Administration, Management. Now, to make it so that you can run the OuterWorlds world server behind a router . . . Click on Applications and Gaming, then DMZ. There, you'll want to enable the DMZ Port and have the DMZ host address assigned by the DMZ port. That's it. :-)
Additional security measures: For starters, I recommend having a firewall program on your computer. Many people go with the free ZoneAlarm one, but, others like the big named stuff, thinking that if it's a bigger company, they'll be safer. Also, to be safe, don't give others eminent domain rights in your world or allow them to use your PPW because it'll allow them to be able to do whatever you can do in your world including destroy all you've built or to create things in your world or in other worlds (like a huge sign, saying nasty things about people using really offensive language) that you will get blamed for, because your name is on it in the object's properties (in
some worlds, you can right-click on an object to see its properties). They can also use your privilege password to destroy any or all of the things that you've built in any world that you still have build rights in. To be even safer, don't even give other people build rights. Make your world entertaining, or have events. There's a lot of other worlds people can build in.