Tip: how to check UDP/10000 connectivity

On the server side

Install ngrep

apt-get install ngrep

and start to watch the UDP/10000 traffic

ngrep -q 'is accessable' udp port 10000

On the client side

Install netcat

apt-get install netcat

and send a message to the server through UDP/10000

echo 'yes, it is accessable' | nc -u your.server.com 10000


If you can see the sent message on the server side, this means that there is no UDP/10000 connectivity problem between this client and the server.


Also I have tested this way: This is on a Mac…

Open a Chrome window with 3 tabs, all of which are connected to the same room.

Open a local terminal window and run:
(you will see lots of traffic on 10000 with 3 Chrome tabs running)
sudo tcpdump -ni en0 port 10000

Open another terminal window,

Run the following to block 10000 udp traffic.
echo "block drop quick on en0 proto udp from any to any port = 10000" | sudo pfctl -ef -

Run the following to enable 10000 udp traffic
echo "block drop quick on en0 proto udp from any to any port = 10000" | sudo pfctl -d

If you have three tabs open with 10000 udp open you will see a lot of activity. When you block 10000 you will see activity slow down, the video in the Chrome tabs will stop and the Chrome tabs will eventually reload. If the tabs reload with 3 good video signals you know failover to 443 worked.

I found this to be a nice visual way to test.


Audio/video does not work if two clients are on different networks

Using this to monitor traffic:

sudo tcpdump -ni ens160 udp port 10000 -vv -X

port 10000 is accessible if I use netcat to connect to it

echo 'yes, it is accessible' | nc -u your.server.com 10000

on the server:

tcpdump: listening on ens160, link-type EN10MB (Ethernet), capture size 262144 bytes
08:05:16.163828 IP (tos 0x0, ttl 52, id 19934, offset 0, flags [DF], proto UDP (17), length 50) > [udp sum ok] UDP, length 22
	0x0000:  4500 0032 4dde 4000 3411 1bea 3b5f 632e  E..2M.@.4...;_c.
	0x0010:  6785 d6e0 dacf 2710 001e 1240 7965 732c  g.....'....@yes,
	0x0020:  2069 7420 6973 2061 6363 6573 7361 626c  .it.is.accessabl
	0x0030:  650a     

but I cannot see any traffic on my jitsi server - port 10000 using the same tcpdump command, when I create a jitsi meeting and connect to it from my laptop+chrome+broadband, and a second client - android jitsi app running on a cellular phone/4G.

What could be the problem?

when you connect 2 clients by default jvb is not used as per default configuration (p2p : enabled in config.js) so port 10000 connectivity does no difference at all.

I see … hmmm.

So - is my understanding correct?

If one client is on a different mobile network and one is on a home network behind a router,
a. port 10000 on the jitsi server does not come into the picture.
b. STUN/TURN is not required - and even if it does come into the picture, it is not connected with port 10000 UDP

as I said by default jvb is not used for 2 clients so they will not connect to port 10000 of the video bridge hence your point a is correct.
as of your point b I don’t use p2p so I can’t comment reliably, from what I hear Stun is necessary for it to work.

a. P2P works differently. As gpatel-fr mentioned, by default JVB is not used in a P2P scenario - both peers negotiate a random port to cimmunicate over.
b. Because 1 of the clients is behind a router, there is no way for the mobile client to determine the home user’s public IP address without STUN (assuming the router is a NAT device). You don’t necessarily have to set up you own STUN server, there are several free ones available, like the google STUN servers. The Jitsi quick install also provides a STUN implementation.

Hi…Just attempted port 80 just as 443 (TCP) and we as a whole realize it IS working, so why there isn’t anything for these port in the container underneath - from your perspective (in your ss).

Do I have to catch traffic from another Ip address… as in my public IP seems to be: and both me and my worker is associated with this equivalent issue (by means of various interface at pfsenses) so would i be able to do bundle catch from this PC or would it be a good idea for me to utilize another PC whose public ip is:

to test you can use this script in the terminal
for i in (seq 1 20); do sleep 3; nc -z -v -u your.domain.com 10000; done

Also, at /etc/jitsi/videobridge/sip-communicator.properties


as per my experience…

How do I test this on Windows?

I have no Windows experience but I can suggest you another option. I prepared an echo service which will send the needed text to your port.

  • run ngrep on Jitsi server

  • run the following command on the second console on Jitsi

curl "http://checkmyport.emrah.com?proto=udp&port=10000&text=is%20accessable"
  • if curl is not already installed, install it first
apt-get install curl

A new method to check UDP/10000 connectivity

Unlike the first method, this new method does not require any client-side action.

on the server

  • Install curl and ngrep packages
apt-get install ngrep curl
  • start to watch the port (it’s UDP/10000 in our case)
ngrep -q 'accessible' udp port 10000
  • connect to a new console and send an echo request to my echo server
curl "http://checkmyport.emrah.com?proto=udp&port=10000&text=it-is-accessible"
  • If you see the sent message (it-is-accessible) on the first console, this means that the port is open to the public.

The third method
Unlike the first method, this method does not require any server-side action.

It seems that this method is not very accurate. The results vary depending on the hosting/cloud providers

On a Linux client

  • Install ncat
apt-get install ncat
  • Try to connect to the server
nc -z -v -u YOUR-HOST-ADDRESS 10000

>>> Connection to YOUR-HOST-ADDRESS 10000 port [udp/*] succeeded!

If you you see the succeeded message, this means that the port is open to the public.

testing this on my server on a random (blocked by default) port gives a successful result and a line in my ufw.log file.

nc -z -v -u emrah.com 54321
Connection to emrah.com 54321 port [udp/*] succeeded!

I only get succeeded message if there is really an UDP server on the server side. Which package provides the nc command in your system?

I’m trying nc from ncat, IIRC netcat-openbsd or netcat-traditional behave differently

well, AFAIK the message you posted (succeeded!) is the one from netcat-openbsd (netcat-traditional answers ‘Open’)

with ncat package on Ubuntu 20.04 (the one from nmap) I get:

nc -z -v -u emrah.com 54321
Ncat: Version 7.80 ( https://nmap.org/ncat )
Ncat: Connected to
Ncat: UDP packet sent successfully
Ncat: 1 bytes sent, 0 bytes received in 2.02 seconds.

sudo update-alternatives --config nc
There are 3 choices for the alternative nc (providing /bin/nc).

  Selection    Path                 Priority   Status
  0            /bin/nc.openbsd       50        auto mode
  1            /bin/nc.openbsd       50        manual mode
  2            /bin/nc.traditional   10        manual mode
* 3            /usr/bin/ncat         40        manual mode

After some tests, I think that the results depend on the hosting providers.

For example on Digital Ocean it’s succeded if there is an UDP service but on AWS it’s always succeded.

On a Ovh server and a Ionos server, same result as AWS.

My server (emrah.com) is on Digital Ocean and the results are completly different for you and me although we use the same tools too :confused: