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I have OpenVPN network with 5 clients.

Computer with Arch Linux which hosts OpenVPN server, It also hosts virtual machine with Computer with CentOS which is also connnected to OpenVPN subnet. Windows 8 which hosts virtual machine with CentOS. Both of them are connected to OpenVPN. Last one machine is virtual machine with CentOS which is hosted by computer with Ubuntu 14( which is not connected to OpenVPN.

All machines in OpenVPN subnet are bolded. All phisical computers are in different networks.

The problem is that when I use nmap to scan Windows and it's guest virtual machine it's saids that host seems down.

When I force namp to scan specific port it shows filtered state:

 nmap -Pn -p 50010 n3
Starting Nmap 6.46 ( http://nmap.org ) at 2014-06-07 19:49 CEST
Nmap scan report for n3 (10.8.0.3)
Host is up (0.11s latency).
rDNS record for 10.8.0.3: node3.com
PORT      STATE    SERVICE
50010/tcp filtered unknown

Telnet also cannot connect to this port

telnet n3 50010
Trying 10.8.0.3...
telnet: Unable to connect to remote host: No route to host

But ss on this host show's proper state of this port

ss -anp | grep 50010
LISTEN     0      50                 10.8.0.3:50010                    *:*      users:(("java",12310,271))

What might be possible reason of that and how to fix it?

EDIT

I've found that I am able to connect via telnet to ssh port:

telnet n3 22
Trying 10.8.0.3...
Connected to n3.
Escape character is '^]'.
SSH-2.0-OpenSSH_5.3

So it seems that it's not problem with Windows firewall. But I have no idea what it might be.

Also nmap result for first thousand ports:

nmap -Pn -p 1-1000 n3

Starting Nmap 6.46 ( http://nmap.org ) at 2014-06-07 20:08 CEST
Nmap scan report for n3 (10.8.0.3)
Host is up (0.49s latency).
rDNS record for 10.8.0.3: node3.com
Not shown: 999 filtered ports
PORT   STATE SERVICE
22/tcp open  ssh

Nmap done: 1 IP address (1 host up) scanned in 77.87 seconds
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1 Answer 1

To answer your title question, it all depends on what port you're running OpenVPN on. Typically, I'll run my OpenVPN server on 443, since most firewalls allow that through. Not allowing that port prevents https traffic from coming through when browsing the web, so it's a pretty safe bet.

The simplest thing to do is turn the Windows Firewall off and try connecting again. If it connects, yeah, it was the firewall.

However, that wont solve your problem. Telnet is telling you there is no route to the host. In other words, if this is a VM setup you either have no virtual network adapter that is configured to connect to your host, or your routing table needs updating, or both.

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I have added more info in first post. –  nervosol Jun 7 at 18:18

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