Warning

Kurento is a low-level platform to create WebRTC applications from scratch. You will be responsible of managing STUN/TURN servers, networking, scalability, etc. If you are new to WebRTC, we recommend using OpenVidu instead.

OpenVidu is an easier to use, higher-level, Open Source platform based on Kurento.

Installation Guide

Kurento Media Server (KMS) is compiled and provided for installation by the Kurento team members, in a variety of forms. The only officially supported processor architecture is 64-bit x86, so for other platforms (such as ARM) you will have to build from sources.

  • Using an EC2 instance in the Amazon Web Services (AWS) cloud service is suggested to users who don’t want to worry about properly configuring a server and all software packages, because the provided template does all this automatically.

  • The Kurento Docker image allows to run KMS on top of any host machine, for example Fedora or CentOS. In theory it could even be possible to run under Windows, but so far that possibility hasn’t been explored by the Kurento team, so you would be at your own risk.

  • Setting up a local installation with apt-get install allows to have total control of the installation process. It also means that it’s easier to make mistakes, so we don’t recommend this installation method. Do this only if you are a seasoned System Administrator.

Besides installing KMS, a common need is also installing a STUN/TURN server, especially if KMS or any of its clients are located behind a NAT router or firewall.

If you want to try nightly builds of KMS, then head to the section Installing Nightly Builds.

Amazon Web Services

The AWS CloudFormation template file for Amazon Web Services (AWS) can be used to create an EC2 instance that comes with everything needed and totally pre-configured to run KMS, including a Coturn server.

Follow these steps to use it:

  1. Access the AWS CloudFormation Console.

  2. Click on Create Stack.

  3. Look for the section Choose a template, and choose the option Specify an Amazon S3 template URL. Then, in the text field that gets enabled, paste this URL:

    https://s3-eu-west-1.amazonaws.com/aws.kurento.org/KMS-Coturn-cfn-6.16.0.yaml
    
  4. Follow through the steps of the configuration wizard:

    4.1. Stack name: A descriptive name for your Stack.

    4.2. InstanceType: Choose an appropriate size for your instance. Check the different ones.

    4.3. KeyName: You need to create an RSA key beforehand in order to access the instance. Check AWS documentation on how to create one.

    4.4. SSHLocation: For security reasons you may need to restrict SSH traffic to allow connections only from specific locations. For example, from your home or office.

    4.5. TurnUser: User name for the TURN relay.

    4.6. TurnPassword: Password required to use the TURN relay.

    Note

    The template file includes Coturn as a STUN server and TURN relay. The default user/password for this server is kurento/kurento. You can optionally change the username, but make sure to change the default password.

  5. Finish the Stack creation process. Wait until the status of the newly created Stack reads CREATE_COMPLETE.

  6. Select the Stack and then open the Outputs tab, where you’ll find the instance’s public IP address, and the Kurento Media Server endpoint URL that must be used by Application Servers.

Note

The Kurento CF template is written to deploy on the default VPC (see the Amazon Virtual Private Cloud docs). There is no VPC selector defined in this template, so you won’t see a choice for it during the AWS CF wizard. If you need more flexibility than what this template offers, you have two options:

  1. Manually create an EC2 instance, assigning all the resources as needed, and then using the other installation methods to set Kurento Media Server up on it: Docker image, Local Installation.

  2. Download the current CF from the link above, and edit it to create your own custom version with everything you need from it.

Docker image

The kurento-media-server Docker image is a nice all-in-one package for an easy quick start. It comes with all the default settings, which is enough to let you try the Tutorials.

If you need to insert or extract files from a Docker container, there is a variety of methods: You could use a bind mount; a volume; cp some files from an already existing container; change your ENTRYPOINT to generate or copy the files at startup; or base FROM this Docker image and build a new one with your own customizations. Check About using Kurento with Docker for an example of how to use bind-mounts to provide your own configuration files.

These are the exact contents of the image:

  • A local apt-get installation of KMS, as described in Local Installation, plus all its extra plugins (chroma, platedetector, etc).

  • Debug symbols installed, as described in Install debug symbols. This allows getting useful stack traces in case the KMS process crashes. If this happens, please report a bug.

  • All default settings from the local installation, as found in /etc/kurento/. For details, see Configuration.

Running

Docker allows to fine-tune how a container runs, so you’ll want to read the Docker run reference and find out the command options that are needed for your project.

This is a good starting point, which runs the latest Kurento Media Server image with default options:

docker pull kurento/kurento-media-server:latest

docker run -d --name kms --network host \
    kurento/kurento-media-server:latest

By default, KMS listens on the port 8888. Clients wanting to control the media server using the Kurento Protocol should open a WebSocket connection to that port, either directly or by means of one of the provided Client API Reference SDKs.

The health checker script inside this Docker image does something very similar in order to check if the container is healthy.

Once the container is running, you can get its log output with the docker logs command:

docker logs --follow kms >"kms-$(date '+%Y%m%dT%H%M%S').log" 2>&1

For more details about KMS logs, check Debug Logging.

Why host networking?

Notice how our suggested docker run command uses --network host? Using Host Networking is recommended for software like proxies and media servers, because otherwise publishing large ranges of container ports would consume a lot of memory. You can read more about this issue in our Troubleshooting Guide.

The Host Networking driver only works on Linux hosts, so if you are using Docker for Mac or Windows then you’ll need to understand that the Docker network gateway acts as a NAT between your host and your container. To use KMS without STUN (e.g. if you are just testing some of the Tutorials) you’ll need to publish all required ports where KMS will listen for incoming data.

For example, if you use Docker for Mac and want to have KMS listening on the UDP port range [5000, 5050] (thus allowing incoming data on those ports), plus the TCP port 8888 for the Client API Reference, run:

docker run --rm \
    -p 8888:8888/tcp \
    -p 5000-5050:5000-5050/udp \
    -e KMS_MIN_PORT=5000 \
    -e KMS_MAX_PORT=5050 \
    kurento/kurento-media-server:latest

Docker Upgrade

One of the nicest things about the Docker deployment method is that changing versions, or upgrading, is almost trivially easy. Just pull the new image version and use it to run your new container:

# Download the new image version:
docker pull kurento/kurento-media-server:6.16.0

# Create a new container based on the new version of KMS:
docker run [...] kurento/kurento-media-server:6.16.0

Local Installation

With this method, you will install Kurento Media Server from the native Ubuntu packages build by us. Kurento officially supports two Long-Term Support (LTS) versions of Ubuntu: Ubuntu 16.04 (Xenial) and Ubuntu 18.04 (Bionic) (64-bits x86 only).

Open a terminal and run these commands:

  1. Make sure that GnuPG is installed.

    sudo apt-get update && sudo apt-get install --no-install-recommends --yes \
        gnupg
    
  2. Add the Kurento repository to your system configuration.

    Run these commands:

    # Import the Kurento repository signing key
    sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 5AFA7A83
    
    # Get Ubuntu version definitions
    source /etc/lsb-release
    
    # Add the repository to Apt
    sudo tee "/etc/apt/sources.list.d/kurento.list" >/dev/null <<EOF
    # Kurento Media Server - Release packages
    deb [arch=amd64] http://ubuntu.openvidu.io/6.16.0 $DISTRIB_CODENAME kms6
    EOF
    
  3. Install KMS:

    Note

    This step applies only for a first time installation. If you already have installed Kurento and want to upgrade it, follow instead the steps described here: Local Upgrade.

    sudo apt-get update && sudo apt-get install --no-install-recommends --yes \
        kurento-media-server
    

    This will install the release version of Kurento Media Server.

Running

The server includes service files which integrate with the Ubuntu init system, so you can use the following commands to start and stop it:

sudo service kurento-media-server start
sudo service kurento-media-server stop

Log messages from KMS will be available in /var/log/kurento-media-server/. For more details about KMS logs, check Debug Logging.

Local Upgrade

To upgrade a local installation of Kurento Media Server, you have to write the new version number into the file /etc/apt/sources.list.d/kurento.list, which was created during Local Installation. After editing that file, you can choose between 2 options to actually apply the upgrade:

  1. Upgrade all system packages.

    This is the standard procedure expected by Debian & Ubuntu maintainer methodology. Upgrading all system packages is a way to ensure that everything is set to the latest version, and all bug fixes & security updates are applied too, so this is the most recommended method:

    sudo apt-get update && sudo apt-get dist-upgrade
    

    However, don’t do this inside a Docker container. Running apt-get upgrade or apt-get dist-upgrade is frowned upon by the Docker best practices; instead, you should just move to a newer version of the Kurento Docker images.

  2. Uninstall the old Kurento version, before installing the new one.

    Note however that apt-get is not good enough to remove all of Kurento packages. We recommend that you use aptitude for this, which works much better than apt-get:

    sudo aptitude remove '?installed?version(kurento)'
    
    sudo apt-get update && sudo apt-get install --no-install-recommends --yes \
        kurento-media-server
    

Note

Be careful! If you fail to upgrade all Kurento packages, you will get wrong behaviors and crashes. Kurento is composed of several packages:

  • kurento-media-server

  • kurento-module-creator

  • kms-core

  • kms-elements

  • kms-filters

  • libnice10

  • libusrsctp

  • openh264

  • openwebrtc-gst-plugins

  • And more

To use a newer version you have to upgrade all Kurento packages, not only the first one.

STUN/TURN server install

Working with WebRTC requires developers to learn and have a good understanding about everything related to NAT, ICE, STUN, and TURN. If you don’t know about these, you should start reading here: About NAT, ICE, STUN, TURN.

Kurento Media Server, just like any WebRTC endpoint, will work fine on its own, for LAN connections or for servers which have a public IP address assigned to them. However, sooner or later you will want to make your application work in a cloud environment with NAT firewalls, and allow KMS to connect with remote clients. At the same time, remote clients will probably want to connect from behind their own NAT router too, so your application needs to be prepared to perform NAT Traversal in both sides. This can be done by setting up a STUN server or a TURN relay, and configuring it in both KMS and the client browser.

These links contain the information needed to finish configuring your Kurento Media Server with a STUN/TURN server:

Check your installation

To verify that the Kurento process is up and running, use this command and look for the kurento-media-server process:

$ ps -fC kurento-media-server
UID        PID  PPID  C STIME TTY          TIME CMD
kurento   7688     1  0 13:36 ?        00:00:00 /usr/bin/kurento-media-server

Unless configured otherwise, KMS will listen on the port TCP 8888, to receive RPC Requests and send RPC Responses by means of the Kurento Protocol. Use this command to verify that this port is open and listening for incoming packets:

$ sudo netstat -tupln | grep -e kurento -e 8888
tcp6  0  0  :::8888  :::*  LISTEN  7688/kurento-media-

You can change these parameters in the file /etc/kurento/kurento.conf.json.

To check whether KMS is up and listening for connections, use the following command:

curl \
  --include \
  --header "Connection: Upgrade" \
  --header "Upgrade: websocket" \
  --header "Host: 127.0.0.1:8888" \
  --header "Origin: 127.0.0.1" \
  http://127.0.0.1:8888/kurento

You should get a response similar to this one:

HTTP/1.1 500 Internal Server Error
Server: WebSocket++/0.7.0

Ignore the “Server Error” message: this is expected, and it actually proves that KMS is up and listening for connections.

If you need to automate this, you could write a script similar to healthchecker.sh, the one we use in Kurento Docker images.

Checking RTP port connectivity

This section explains how you can verify that Kurento Media Server can be reached from a remote client machine, in scenarios where the media server is not behind a NAT.

You will take the role of an end user application, such as a web browser, wanting to send audio and video to the media server. For that, we’ll use either of Netcat in the server, and either the same or Ncat in the client (because Ncat has more installation choices).

The check proposed here will not work if the media server sits behind a NAT, because we are not punching holes in it (e.g. with STUN, see When are STUN and TURN needed?); doing so is outside of the scope for this section, but you could also do it by hand if needed (like shown in Do-It-Yourself hole punching).

First part: Server

Follow these steps on the machine where Kurento Media Server is running.

  • First, install Netcat, which is available for most Linux distributions. For example:

    # For Debian/Ubuntu:
    sudo apt-get update && sudo apt-get install --yes netcat-openbsd
    
  • Then, start a Netcat server, listening on any port of your choice:

    # To test a TCP port:
    nc -vnl SERVER_PORT
    
    # To test an UDP port:
    nc -vnul SERVER_PORT
    

Second part: Client

Now move to a client machine, and follow the next steps.

  • Install either of Netcat or Ncat. On Linux, Netcat is probably available as a package. On MacOS and Windows, it might be easier to download a prebuilt installer from the Ncat downloads page.

  • Now, run Netcat or Ncat to connect with the server and send some test data. These examples use ncat, but the options are the same if you use nc:

    # Linux, MacOS:
    ncat -vn  -p CLIENT_PORT SERVER_IP SERVER_PORT  # TCP
    ncat -vnu -p CLIENT_PORT SERVER_IP SERVER_PORT  # UDP
    
    # Windows:
    ncat.exe -vn  -p CLIENT_PORT SERVER_IP SERVER_PORT  # TCP
    ncat.exe -vnu -p CLIENT_PORT SERVER_IP SERVER_PORT  # UDP
    

    Note

    The -p CLIENT_PORT is optional. We’re using it here so the source port is well known, allowing us to expect it on the server’s Ncat output, or in the IP packet headers if packet analysis is being done (e.g. with Wireshark or tcpdump). Otherwise, the O.S. would assign a random source port for our client.

  • When the connection has been established, try typing some words and press Return or Enter. If you see the text appearing on the server side of the connection, the test has been successful.

  • If the test is successful, you will see the client’s source port in the server output. If this number is different than the CLIENT_PORT you used, this means that the client is behind a Symmetric NAT, and a TURN relay will be required for WebRTC.

  • If the test data is not reaching the server, or the client command fails with a message such as Ncat: Connection refused, it means the connection has failed. You should review the network configuration to make sure that a firewall or some other filtering device is not blocking the connection. This is an indication that there are some issues in the network, which gives you a head start to troubleshoot missing media in your application.

For example: Assume you want to connect from the port 3000 of a client whose public IP is 198.51.100.2, to the port 55000 of your server at 203.0.113.2. This is what both client and server terminals could look like:

# CLIENT

$ ncat -vn -p 3000 203.0.113.2 55000
Ncat: Connected to 203.0.113.2:55000
(input) THIS IS SOME TEST DATA
# SERVER

$ nc -vnl 55000
Listening on 0.0.0.0 55000
Connection received on 198.51.100.2 3000
(output) THIS IS SOME TEST DATA

Notice how the server claims to have received a connection from the client’s IP (198.51.100.2) and port (3000). This means that the client’s NAT, if any, does not alter the source port of its outbound packets. If we saw here a different port, it would mean that the client’s NAT is Symmetric, which usually requires using a TURN relay for WebRTC.