You have a firewall. It's called "don't run services you don't need or don't understand" and "if it binds a non-localhost port it better be secure." It's easy

You have a firewall. It's called "don't run services you don't need or don't understand" and "if it binds a non-localhost port it better be secure." It's easy to use netstat to list all bound ports for TCP and UDP. I know on Linux there is also a flag to show the owning pid. Do that and then investigate any you don't recognize. If you don't need it turn it off. Otherwise check it's security record and config.