Socket.io does not work on the ubuntu 16.04

Question

I have an issue with socket.io. When I run my code on my computer (local) I can use http://IP:120/socket.io/socket.io.js. However, on my server (Digital ocean server ubuntu

Answer 1

The solution is related to setting up the ports required for the communication.
By default, all ports except :80 are blocked in Digital Ocean

You need to open your port 120 first:

iptables -I INPUT 1 -i eth0 -p tcp --dport 120 -j ACCEPT