HOWTO : Ports and stuff

If you got some trouble or need help configuring AirDC++, we're here to help

HOWTO : Ports and stuff

Postby en_dator » 05 Nov 2008, 18:45

While most of dc is pretty simple and straight forward, the thing with ports seems to be the one thing that many people get confused about, and rightly so as it is not normally something you deal with. Other types of application (like torrents and IM clients) usually handle this by themselves without help from the user. Here dc is a bit different and it requires a little work from you as a user.

First topic : active or passive
Really short version : passive works, but active is better.

Now why is that? Well for one thing, if you are a passive user all communications goes through the hub wich means you will spend more of its bandwith. But the major thing that is negative for you if you are in passive mode is that you can not download from other that are also in passive mode (= less sources ).

If you on the other hand is in active mode, all search replies will be sent directly to you from the user instead of via the hub (means no restrictions from the hubsoft). And all downloads are initiated directly between you and the source.

So, unless you have no other option, try to use active mode.
(insert silly analogy here : compare - if you are active and buy the girl a drink you might get lucky, if you sit in the corner waiting, she will leave with that other dude that did buy her a drink = active gives you more chances to get lucky :) )

How does it work then?
In AirDC++ (as most other clients) you have three different configuration options to get you in active mode where the first one is the simplest one "Direct connection", this you can use if you have no router and are connected directly to the network.

Second option is "Firewall with UPnP", personally I never really liked this one (probably because my router never got it right). The idea here is that the dc client asks the router for ports, the router opens the ports and tell AirDC++ which to use and if all goes well you're all set to go. Now, if you are paranoid there are some security concerns with this, for example - how do you know the ports get released and closed when the clients shuts down, or even worse - if you allow your router to use UPnP that means any application that requests a port will get one, without even asking you about it (thats the other part I dont like). But still, it's a good idea when it works. The choice is as always up to you (Wiki article on UPnP =

Third option "Firewall with manual port forwarding", which is the one I believe most are using as it gives you control, but on the other hand it requires a little more of you (just a little). For this option there are some settings that you must set. External/ WAN IP, three different port numbers and then there are two checkboxes that you need to decide whether to check or not.

We start with the IP, easiest is to just press the button where it says Get IP, under normal circumstances it should be able to get you the correct IP (if it doesn't, then you should not enable the setting "Update IP on startup"!).
If you dont understand what internal IP or external IP means, there is a good Wiki article here = If it looks like the IP in the box is the correct one enabling the "Update IP on startup" is probably a good idea, even if you are on a static IP it wont hurt. The other setting "Don't allow hub/UPnP to override" that one I suggest you leave unchecked for now.

The three little boxes where it says TCP, UDP and TLS is the next thing we need to take care of, and it is here where things start to get tricky. If you know how to set up NAT (or portforwarding) for your router then just go ahead and do so, I suggest you use three different port numbers in the range from 1024 to 65536. If you dont understand what NAT or port forwarding is here are two external links that will explain it all and ... ranslation .

The fourth and last option is if none of the above works and thats "Firewall Passive". for this you do not need to set anything up

So lets say we did choose active mode using one of the options above, how can I tell if it works or not?
Actually this is very simple - to test if your active mode settings work, just search for something that you know exists (for example 'music'), if you don't get any search replies back, then something is wrong with your settings.

You can test your ports on this page :

Some external resources that will help you if you have more questions:
Port Forwarding (this is a recommended read)
NAT ... ranslation
Private (or internal) IP

And here is a page with information on setting up a large number of different routers :

If you cant find your router in that list, my best advice is to look for something in your router similar to "virtual server" as that is most likely the correct place to add forwarding rules, and to avoid settings that talk about "trigger ports" as that is not usually suitable for DC clients.


(Note! Please do not ask help questions in this thread - Keep this thread clean and only about this HOWTO. Please make your questions in a separate thread)
User avatar
Site Admin
Posts: 486
Joined: 22 Sep 2008, 22:32

Return to The Help Desk

Who is online

Users browsing this forum: Bing [Bot] and 4 guests