Configure remote access for Docker daemon

By default, the Docker daemon listens for connections on a Unix socket to accept requests from local clients. You can configure Docker to accept requests from remote clients by configuring it to listen on an IP address and port as well as the Unix socket.

Warning

Configuring Docker to accept connections from remote clients can leave you vulnerable to unauthorized access to the host and other attacks.

It's critically important that you understand the security implications of opening Docker to the network. If steps aren't taken to secure the connection, it's possible for remote non-root users to gain root access on the host.

Remote access without TLS is not recommended, and will require explicit opt-in in a future release. For more information on how to use TLS certificates to secure this connection, see Protect the Docker daemon socket.

Enable remote access

You can enable remote access to the daemon either using a docker.service systemd unit file for Linux distributions using systemd. Or you can use the daemon.json file, if your distribution doesn't use systemd.

Configuring Docker to listen for connections using both the systemd unit file and the daemon.json file causes a conflict that prevents Docker from starting.

Configuring remote access with systemd unit file

1. Use the command sudo systemctl edit docker.service to open an override file for docker.service in a text editor.

2. Add or modify the following lines, substituting your own values.

   [Service]
   ExecStart=
   ExecStart=/usr/bin/dockerd -H fd:// -H tcp://127.0.0.1:2375

3. Save the file.

4. Reload the systemctl configuration.

   $ sudo systemctl daemon-reload
   

5. Restart Docker.

   $ sudo systemctl restart docker.service
   

6. Verify that the change has gone through.

   $ sudo netstat -lntp | grep dockerd
   tcp        0      0 127.0.0.1:2375          0.0.0.0:*               LISTEN      3758/dockerd
   

Configuring remote access with daemon.json

1. Set the hosts array in the /etc/docker/daemon.json to connect to the Unix socket and an IP address, as follows:

   {
     "hosts": ["unix:///var/run/docker.sock", "tcp://127.0.0.1:2375"]
   }

2. Restart Docker.

3. Verify that the change has gone through.

   $ sudo netstat -lntp | grep dockerd
   tcp        0      0 127.0.0.1:2375          0.0.0.0:*               LISTEN      3758/dockerd
   

Allow access to the remote API through a firewall

If you run a firewall on the same host as you run Docker, and you want to access the Docker Remote API from another remote host, you must configure your firewall to allow incoming connections on the Docker port. The default port is 2376 if you're using TLS encrypted transport, or 2375 otherwise.

Two common firewall daemons are:

• Uncomplicated Firewall (ufw), often used for Ubuntu systems.
• firewalld, often used for RPM-based systems.

Consult the documentation for your OS and firewall. The following information might help you get started. The settings used in this instruction are permissive, and you may want to use a different configuration that locks your system down more.

• For ufw, set DEFAULT_FORWARD_POLICY="ACCEPT" in your configuration.

• For firewalld, add rules similar to the following to your policy. One for incoming requests, and one for outgoing requests.

  <direct>
    [ <rule ipv="ipv6" table="filter" chain="FORWARD_direct" priority="0"> -i zt0 -j ACCEPT </rule> ]
    [ <rule ipv="ipv6" table="filter" chain="FORWARD_direct" priority="0"> -o zt0 -j ACCEPT </rule> ]
  </direct>

  Make sure that the interface names and chain names are correct.

Additional information

For more detailed information on configuration options for remote access to the daemon, refer to the dockerd CLI reference.