Open Port 2375 for Docker API

1. Create daemon.json file in /etc/docker:

    {"hosts": ["tcp://0.0.0.0:2375", "unix:///var/run/docker.sock"]}

2. Add /etc/systemd/system/docker.service.d/override.conf

    [Service]
    ExecStart=
    ExecStart=/usr/bin/dockerd

3. Reload the systemd daemon:

    systemctl daemon-reload

4. Restart docker:

    systemctl restart docker.service

5. firewall

ufw allow 2375/tcp
ufw reload