Checking TCP/UDP ports!

Even this post is rather old, but it still comes up with the search results so I would like to reply a solution to the question.

You can open the Terminal in Mac (type terminal on Spotlight) and then use NetCat command by typing like a sample below to test your specific port like this replacing 1xx with your target IP address, then the port to check.

>nc -vnzu 1xx.xxx.xxx.xxx 53

or if you want to check a range of ports for example from port 1 to 53, just type

>nc -vnzu 1xx.xxx.xxx.xxx 1-53

NetCat is already a built-in command in Mac so no need to install anything.

Hope this helps.

avp3000 wrote:

I was looking for the same thing and I found this artile by Applie, which helped me:

http://support.apple.com/kb/PH10793

FWIW, this is the utility that was referenced earlier in the thread.

In OS X 10.9, the Network Utility app is still around, but it's been hidden away. To quicky find it in Mavericks, use Spotlight search and enter Network Utility in the search box.

The "wording" for the Port Scan part of Network Utility seems to apply that it is scanning for TCP port status (and not UDP). Is this actually the case? I'm trying to diagnose if my L2TP VPN service on my OS X Server machine is open for business, and nothing is showing with Network Utility. (The PPTP port, which is TCP, as opposed to L2TP's UDP connection, shows up just fine.)

If something like nmap is the answer, then I'll need some handholding on where to find it / run it (I expect via Terminal, which by itself is not too daunting, but at the moment "man nmap" doesn't bring up anything.

If you are on the machine that has ports mapped to it, you can test the TCP ports using a tool like http://www.whatsmyip.org/port-scanner/

You would likely have to have the service up and running so the port test has something to connect to on the destination end.

I was looking for the same thing and I found this artile by Applie, which helped me:

http://support.apple.com/kb/PH10793