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