What is using UDP port 1900 within openHAB?

Setup, Configuration and Use Runtime
1

I am using openHAB 2.5.11 on a Raspberry 4 with raspbian OS. I ran into an error when installing some software that requires port 1900 UDP (unifi controller) and found out that openHAB is using that port. I am not able to find out, what binding is causing this.

The bindings I use are: mqtt,astro,exec,fritzboxtr0641,kodi,weather1,wol1,network,systeminfo,tcp1
I have configured the tcp1 binding to listen on UDP 40001 and nothing else.

My research showed that UPNP uses UDP 1900 - is this an OH thing or is some binding using it? What logs could I enable to find out more?

2

I did the following:

netstat -tulpn | grep 1900

and got

udp        0      0 0.0.0.0:1900            0.0.0.0:*                           4849/deCONZ     
udp6       0      0 :::1900                 :::*                                1481/java

for my instance.

As far as I understand https://github.com/openhab/openhab-addons/issues/698 OH itself plus a subset of bindings require this port to join UPNP.

3

I did the same and that’s how I found that OH is listening on that port. The question for me is what is causing this, do I need this and could I prevent it.
I have started poking around with a blank docker openhab image and it seems the issue is with hue & deconz binding. Setting the following in runtime.cfg did not help though

discovery.deconz:background=false
discovery.hue:background=false
discovery.upnp:background=false
4

You can use e.g. nmap to get information about the UPNP service behind port 1900 by running

nmap -sU -p 1900 --script=upnp-info  YourServerHere

In case of deCONZ the reply will look like:

PORT     STATE SERVICE
1900/udp open  upnp
| upnp-info: 
| 192.168.0.26
|     Server: Linux/3.14.0 UPnP/1.0 IpBridge/1.26.0
|_    Location: http://192.168.0.26:8090/description.xml
MAC Address: 22:DD:55:00:EE:68 (Unknown)

In case you disabled e.g. deconz, hue and the port is still in use I would expect to get a different content then.

5

Are we talking about the same things or did I get something wrong? I know that openHab is listening on 1900 UDP, but would like to find out which binding. I already found out that a fresh openHAB does not listen on the port, but as soon as I add hue or deconz it does. Wouldn’t nmap output always look the same when openHAB is listening?

Nonetheless, here is the output I am getting from your command:

Starting Nmap 7.70 ( https://nmap.org ) at 2020-12-20 16:49 CET
Nmap scan report for localhost (127.0.0.1)
Host is up.

PORT     STATE         SERVICE
1900/udp open|filtered upnp

Nmap done: 1 IP address (1 host up) scanned in 8.04 seconds
6

Hue binding for example uses openHABs UPnP implementation, therefore you will only find openHAB listed in nmap.
There are some bindings using UPnP.

7

OK, so there seems no way to find out which binding is using upnp besides trial&error. Also it seems that not all bindings regard the discovery.BINDING:background=false setting - I assume it is not mandatory or should I file an issue with the bindings?

Probably I can ignore this now, since I moved my installation to docker without host-networking so that I can decide to not forward port 1900/udp.