This article is a stub by a non-expert which I hope people who actually know diddly squat will expand & correct. Use at your own risk - it probably won't blow up your computer, burn the house down or get you accused of being a Russian hacker, but, hey, you never know. It's better than nothing, or at least I hope it is, and gets the wiki ball rolling.
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-- Nomenclature & Background --
[skip this part if you know it all]
A "port" in this context is not a physical thing - basically it is just an arbitrary, convenient numeral used to label unsolicited information coming in from the net, so that the local system can manage the local distribution of that information in different ways depending on what that number is and what local settings are. Information labeled in this way with the numeral 1089 for example is said to be "sent to port 1089". There are 2 places where the port number affects how the system deals with the information:
1- Routers usually default to discarding all unsolicited incoming information. They can be set to send information sent to specific ports to specific computers among those they serve. It's like the router is a door guard (aka "porter", fancy that) at a very secure office building. The building corresponds to the group of computers the router serves. Each office corresponds to a particular computer in the group. The guard's general policy is to send away anyone without an explicit invitation. But he can be given additional instructions like "Anyone who shows up with any of the passwords on this list I'm giving you [corresponding to a set of port numbers] should be sent along to the offices of Amalgamated Widgets on the 3rd floor [corresponding to a particular computer]. Setting a router to do this is called by such expressions as "opening a port", "enabling port forwarding", or "setting up port forwarding". "Forwarding" as in "forwarding mail" because it will forward the info to the specified computer (or computers) rather than discard it.
- Once the information gets to the particular computer the port number determines which running programs will take note of it. Those programs are said to be "listening on port N", N being whatever the port number is.
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-- General Procedures & Points --
So the general goal is to tell the router to send any information that comes in on port 1089 to your particular computer (which might or might not be the only one the router serves). First, it helps to know what kind of router it is. Might be easiest to look at it & read all the labels. While you're looking, the model name or number could prove helpful. In linuxes, you could also enter this in a terminal:
ip route | grep default|cut -d' ' -f3
and it will probably give you an ip number. Enter that in the address bar of a web browser and it will probably take you to a page from the router that will tell you the brand and maybe model. Now you can use a search engine like duckduckgo.com & find the manufacturers website & somewhere on it you can probably find instructions for configuring the router. If a password is required & you don't know it, the website will probably tell you what the default password as shipped is. If that doesn't work, try an empty field (i.e., password="" without the quotation marks). If that doesn't work, call up whoever set up the router for you and ask them politely. If that doesn't work, try pulling out their toenails. Alternately, there is usually a mechanical way (meaning something you can do if you have physical possession of the router) (like holding some recessed button down for 30 seconds while reciting the 3 laws of robotics for example) to reset the router to its as-shipped state including resetting the pass to its original default. That procedure should be detailed on the website. But if you use the wireless feature of the router, avoid having to reset it if you can, because you may find the network password reset as well which would disable wireless use until you get that figured out.
You are probably going to need the local ip number of your computer, which is NOT the same as your internet ip number, although it takes the same form. If you're using a linux entering this in a terminal will probably get it for you:
ifconfig|grep 'inet addr:19'|cut -d':' -f2|cut -d' ' -f1
UPnP: Don't worry about this unless the preceding fails. It is an alternate mechanism & hopefully somebody will fill in more detail here eventually.
Don't forget to check your software firewall too. Might be easier to turn it off until you get this set up & working. Then get the firewall rule right. For people who use ufw, if you have trouble getting it to cooperate, try the gui front end "gufw".
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-- notes on specific router brands --
Belkin:
I found my router here: http://192.168.2.1/
& that linked to the configuration page here:
http://192.168.2.1/fw_virt.html
If you haven't set the pass, try just clicking "submit" with the field empty. Then try setting it like the attached photo. Good chance you'll need a different number in the "provide ip" field. Procedures for getting that are given above in the "Nomencature & general points" section above. Note that here you only have to enter 1 digit of the ip. May not be exactly the same for you, but at least you have an example. This is what worked for me:
I've used the port yacy defaulted to, but I'm wondering if it wouldn't be more secure to pick a random number. I haven't tried that.