Allow connection to a Flask app only from Angular app

Hi there!

I have Flask (port 5000) and Angular (port 80) running on my droplet. I’d like to allow connections to my Flask backend only from the Angular app. I configure my firewall rules using ufw. From what I understand, the commands below should do the trick:

sudo ufw deny 5000/tcp
sudo ufw allow from to any port 5000 proto tcp

Unfortunately they doesn’t work and I end up with the Flask app being inaccessible from any IP. Is there any other way to achieve my goal? Perhaps other ufw rules?

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It is possible that the outgoing TCP connections on port 5000 are not allowed on your Angular Droplet. To test that what you could do is SSH to the droplet and then run:

telnet 5000

If you are unable to connect then you have to open port 5000 for outgoing TCP traffic on your frontend Droplet, you could do this with this command:

sudo ufw allow out 5000

Let me know how it goes! Regards, Bobby

Sorry for a duplicated question (and for posting my droplet IP. I should have mask it, unfortunately there is no edit option).