I will go into more detail
first of all HOW to port forward. open the windows command prompt, type "ipconfig" and press enter. this is useful for two reasons: it tells you what IP you need to visit in your browser to get to your router settings, and it tells you what your local IP address is
you should see something that looks like this
there might be a couple of other entries, depending on your computer (I have several extra, mostly VM stuff), but chances are only one of them will have
all of this info
then visit the "Default Gateway" IP in your browser, and look for something that mentions port forwarding. with my router, there's a section for "Applications and Gaming" and it's in there. you should see something like this
for your purposes, both internal and external ports should be the same, and they should be whatever port you wanna host on. then make sure the IP address section matches the "IPv4 Address" part of what you got from the ipconfig command (depending on the coolness of your router, it might have already picked that one for you). I
think just setting it to TCP will work, but I'm not completely certain, so maybe ask someone else about that. and, obviously, check the "enabled" box, if your router also has such a thing
then start up a server on the port you chose. it should work, unless there's another problem
if you want to host another server on the same computer, under a different port, you'll have to forward that one to your computer too
also, if you don't want to have to worry about occasionally correcting these settings, you might wanna set a static IP address for your computer. this is more complicated, but still easy. there are two ways to do it, and I would suggest doing both
method #1: through your operating system
I'm assuming you use windows. I also assumed that earlier with the command prompt stuff. if you don't use windows, google this part
go to the network and sharing center in the control panel. then on the left side, click "change adapter settings," and there should be a few options. chances are, there will be one for every entry there was in the ipconfig results. right click on whichever one you're using, and click "properties"
then, in the list, find and select "Internet Protocol Version 4" and click "properties" (or you can just double click on it in the list). this is where you can choose whether to get an IP address automatically from the router when you connect, or use a static one. this is what my settings look like:
hopefully I don't really need to explain the stuff in the first section. it should match the ipconfig info, unless you want to choose a different IP address ending. if you
do wanna change it, only change the final part, which in my case is "123." there might be some restrictions on what numbers you can choose, so you should just use the same one you already had, cus you know it'll work
at this point, it may require you to choose a DNS server instead of using whatever DNS server your router is set to. I don't know why, but if it does, the ones I have it set to are a good choice. they're Google's public DNS servers. you could use a different one if you wanted, but I suggest Google's
then click "okay" on that window and the one before it, and you're done
method #2: through your router
if you only do it through your OS, you may run into issues if there are other people connecting and disconnecting to the router often. your router might automatically assign the IP address you wanted to another device, and that would suck for you, when your computer wants the one you set
this is a little more complicated, and probably changes quite a bit depending on what router you have. somewhere in your router settings there should be something called "DHCP reservation" or maybe "IP address reservation" or it might just say something about static IP addresses. this is what you want. you should just have to enter the IP address you want reserved and the MAC address you want it reserved for. the MAC address is an identifier for your computer. it might want a nickname for the computer too. to find the MAC address you need to use, you can go back to the command prompt, and use the ipconfig command again, but this time add "/all" after it. the entire command should look like "ipconfig /all" without the quotes. find the same entry as before, and this time you're looking for the "physical address"
these explanations are certainly imperfect, so if you have any questions, ask
now for the other thing. that you only need to read if you're interested. WHY you have to forward ports
when you have a router, many devices can be connected at once. and when some seemingly random piece of data (that is, not a response to a request that you sent) reaches your router from elsewhere on the internet, it can't just send it to every computer on the network and hope one of them is right. so the router needs to know in advance who's supposed to get it. and that's what port fowarding is for. whenever the router gets something headed to port 1337, it knows to send it to the computer at 192.168.1.123, under that same port (unless you chose a different internal port), since you set it up that way. and you have around 65535 ports to choose from (minus the ones already in use), so don't worry about running out
