Are all ports open?

Yes, all ports are open on our servers. You have no restrictions. The software firewall (iptables) is set to „ALLOW“ by default.

So if you start a program on your Linux server that opens a port publicly, you do not need to explicitly open it. So you don’t need to perform explicit port forwarding, as you might have to do at home, for example.

It’s a bit different with Windows servers. There, you need to open the ports in the Windows firewall to be able to reach them from the outside.

My program is not accessible from the outside

If your program is not accessible from the outside, first check your firewall. Usually, however, the issue lies with the program’s listening method. If the port is open on „127.0.0.1“, you can only access the port from the machine itself. You would need to either set your own IP address as the „bind“ IP or use „0.0.0.0“. This will make your program accessible from the outside.

We also have a separate article on making a MySQL Server accessible from the outside.