I have a Ubuntu box connected to a wifi router. This wifi router is connected to a d-link adsl modem/router. I am preparing this Ubuntu box to run a server that will use some special ports in UDP and TCP. I have setup this wifi router to put my Ubuntu box on a DMZ. So, the Ubuntu is on the DMZ of the wifi router, what means it is still on the local network of the D-link.

The big question is: how do I test, using Ubuntu, if these special ports are getting thru? I mean: there is some command I can type to check if a port is getting thru and certify that the computer is really on DMZ?

Part on the premise that the D-link is port-forwarding the ports correctly.


I would say tcpdump on the Ubuntu box, and netcat on anything that should act as the client.

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  • any examples on how to use the commands? lets say I wanna test port 443. – Duck Dec 31 '11 at 3:20
  • tcpdump host <host> and port 443 and nc <host> 443. – S19N Dec 31 '11 at 3:23

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