step1
sudo vim /usr/lib/systemd/system/docker.service
step2
insert “ -H tcp://0.0.0.0:4243 -H unix:///var/run/docker.sock” 
在ExecStart后面添加append -H tcp://0.0.0.0:4243 -H unix:///var/run/docker.sock
- step3
sudo systemctl daemon-reload //refresh your file changes above
- step4
sudo systemctl restart docker
- step5
netstat -l | grep 4243 //verify port is open
