While we were configuring the Firewall on our Synology NAS. We found it useful to have a quick way to check if ports that we were working with were open or closed.
So built into macOS is a tool called Network Utility, which is a free way to check the state of our firewall. Please note that Network Utility does have limitations but seems to work well when checking if a single port on our NAS is open or closed.
Quick reference notes:
- From the desktop of macOS, select Spotlight search
- Within the search field enter Network Utility
- Select Network Utility from the list of results
- From the buttons at the top of the Network Utility windows select Port Scan
- Enter the IP address of your Synology NAS
- In Only test ports between enter the same port number into both fields
- Press the Scan button
Notes: While you can test a range of port numbers, for example ports between 150 and 200. As most of those ports will be closed, you will have to wait for Network Utility to time-out for each port. As the test for each closed port will take roughly 70 seconds. If you test a range of ports, it will take a considerable amount of time.
If you need to test the whole firewall on your NAS, or you wish to test a range of ports. It would be more time efficient to use a full network scanning application.
- Apple Support – Use Network Utility on Mac