Question

How do I get my droplet to listen to port 4000 and port 27017

So my company has a webserver on port 4000 (Cloudflare) and mongodb on port 27017. I tried to do ufw allow 27017/tcp, or ufw allow 27017, ufw allow 4000, ufw allow 4000/tcp. However when I’ve done an nmap scan the ports are still closed for some reason. Why is this? What am I missing? I’ve tried to enable nginx and apache but we already have a webserver on cloudflare, so isn’t it mood point?

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Bobby Iliev
Site Moderator
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• June 28, 2022

Hi there,

In order for you to be able to access those services externally, besides allowing the ports via your firewall, you need to make sure that they bind on 0.0.0.0 rather than 127.0.0.1.

For example, with MongoDB you can do that by following the steps here:

https://www.digitalocean.com/community/tutorials/how-to-configure-remote-access-for-mongodb-on-ubuntu-20-04

For the service that is listening on 4000, can you confirm what type of service is it?

Best,

Bobby

Sergio Turpín • June 28, 2022

Hello there,

What is your problem? Your droplet has this ports open but you can’t to connect to them?

From your Droplet

Check out your open ports

  1. netstat -putan

Check out the current status of your firewall

  1. sudo ufw status verbose

From outside your Droplet

Check out your open ports

  1. nmap your_droplet_ip

If you need to check a specific port

  1. nmap -p 4000 your_droplet_ip

Hope this helps,

Sergio Turpín

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