How can I check the openness of the ports of the provider, router, PC?

Question

macOS

There are access problems on some ports and I can’t find the culprit, I have already excluded everything, but with variable success. How can I check ports at least from 0 to 1000? and how can you track where the packets reach, something like traceroute?

Answer 1

OS X has a standard Network Utility (" Network Utility ")

Answer 2

How can I check the openness of the ports of the provider

As a rule, port providers do not close, at least I have never encountered this. They do not need to do this - unnecessary technical difficulties that do not bring profit.
Unless on hostings mail ports are sometimes covered in order to avoid spam, and then they warn about it.
The port is considered open if there is an application that "listens" on the port - that is, it processes packets that come to this port, and it is not blocked in the firewall.
Accordingly, look at the firewall settings on the router, computer, as well as the presence of applications that process packets from this port.

There are access problems on some ports

what kind of problems?

how can I trace where the packets reach, something like traceroute?

Actually traceroute is intended for this.

Answer 3

I think that ports 22 and 23 are needed by the router itself and are configured on the external interface, but if these services are turned off and the router settings do not reflect reality, then it turns out that you cannot get to these ports from the outside.
Look at the service data on the router itself or try changing its port.

Answer 4

You can see which ports are open and what (on a given device) you can use netstat .

Answer 5

general nmap foundation of basics + Kali