Here's a simple 4 and a half minute tutorial video on how to do port forwarding for Minecraft servers. This seems to be the biggest sticking point when folks try to run a server for their friends, especially if this is the first server they've ever run or they only have limited experience running a server. I've noticed a lot of users asking for instructions on the Minecraft Forums but there are some things that are easier to understand when shown vs. when instructed via text.
A few things to remember:
- This assumes your Minecraft server is up and running, that you are attempting this on residential Internet, and that you do not have static IPs (probably 99% of folks out there).
- It's possible that your external and internal IPs may change. If, one day, things stop working, don't forget to ensure your port forwarding is still pointing to the correct server and your friends still have the right IP to connect to.
- It's okay to be excited when it finally works.