Hey folks, you’re a little bit crazy to advise or to accept using VNC without tunneling it throug a VPN and to make an end user desktop device direct available to the internet by portforwarding. Even more in case of a remote access tool. Great invitation to unwanted visitors discovering your device, @drmacro, by a portscan in the twinkling of an eye.
I do not agree. By comparison it’s a mutch better idea to use something like Teamviewer than implementing a direct reachable VNC-Server. You know about the security issue but proceed to advise. The OP seems not to know and is just desperately seeking a remote support option and would use what ever by chance works - masking any security risks.
@drmacro, you could take account of using something like Teamviewer to install the VPN-Client on the remote device. Also to change IP configuration from DHCP to fixed IP so that your target device is available at always the same local subnet IP and also to install the according VNC-Server for further assistance later without having to use services like Teamviewer then. That could be a reasonable way to proceed. In that case you don’t need portforwarding and you’re tunneling VNC secure through a VPN-Connection.
Of course the WAN IP of your Comcast box responds to ICMP ping. But hopefully there is a firewall on that box and the target device is behind that firewall? Or is it really that way you described it at the beginning, that your target device is connected directly to the internet only with the software firewall of the choosen Linux protecting it? But also in that case, it’s the WAN side that is responding to your pings and the hopefully active firewall would block anything else inbound. E.g. the attempt to reach a local VNC-Server on Port 5900.
Regards,
Simulacron