# howto detect if some host is running openvpn service?

## shallpion

If I know the IP of some machine and I want to know if it is running openvpn service, what should I do? I tried to use nmap but what I can see is only there is a udp port open, but not sure it is for openvpn. Is there any tools can do this job? Thanks.

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## richard.scott

Due to OpenVPN being encrypted I would guess that the only way to see if its OpenVPN listening on a port is to try and connect a client to it.

In my experience, nmap doesn't seem to provide any extra info other than the ports open

Rich

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## d2_racing

Do you have a physical access to it ?

If so, just plug a hub on it and then start wireshark on your box.

With that, you will be able to sniff all the communication and since you use a hub, it's invisible  :Razz: 

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## shallpion

Well I am afraid not  :Sad: 

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## malern

You can use the -sV option with nmap

 *Quote:*   

> −sV: Probe open ports to determine service/version info 

 

It's pretty good at working out what service is running on a port.

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## richard.scott

nmap -sV doesn't provide any results for me for port 1194... its as if its not even open (even tho OpenVPN Server is running and working).

Rich

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## shallpion

I am not sure if I am correct : nmap by default doesn't scan high port, so you can try

nmap -p 1-65536 -sU localhost

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## d2_racing

Indeed, you need to specify the range ports.

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