Most organisations have security rules that stop non-standard ports on external resources from being accessed from the corporate network. One frequent scenario is when you are running a website on a non-standard port (e.g., 5000 ) on AWS EC2 (e.g., 52.131.143.12 ) and you try to call it from your corporate network. In most cases, if you open your browser and try to access http:// 52.131.143.12 :5000 , the site won't load despite having the port open on AWS EC2 Security Group . To overcome this limitation you can use Reverse SSH Tunneling the following way: Open a terminal and navigate to the folder where you have your PEM key to connect to AWS EC2 Type ssh -i your_key.pem -NL LOCAL_PORT:localhost:REMOTE_PORT ec2_user@xxx.xxx.xxx.xxx ( e.g., ssh -i your_key.pem -NL 8080:localhost:5000 ec2-user@52.131.143.12 ). Leave the terminal open with the SSH command running. Open on your browser and type http://localhost:LOCAL_PORT (e.g., http...