Maybe it is not a good idea to open your network (port forwarding), without knowing how it is working. Even if the goal is a much more secure solution (VPN).

In short:

  • You are ‘dial in’ at your provider, with given user/password.
  • Your provider assign an IP to your router.
  • The whole Internet should be able to reach your router via this IP.
  • But because of your router got no monitor/keyboard/mouse, there are other Systems behind.
  • The Router has one IP on WAN (assigned by Provider) and a Network (mostly 192.168.00/24) on the other side.
  • Because all possible 245 devices in the internal network has to share one IP, the router knows some magic: NAT (Network Address Translation).
  • If a device is connecting from the inside to the internet, the router knows 'ah, there is a established connection, i know from my NAT table who is the origin and where to route the answers.
  • But this ‘workaround’ can’t work from the outside. How should the router decide which device can answer services at port 1234?
  • Here comes the ‘port forwarding’.
  • One device in your network (f.ex. 192.168.0.224) is able to speak VPN on port 1234. But this port is only known in your internal network.
  • So the router needs to know 'if some device asking at WAN for xx.xx.xx.xx:1234 (WAN IP) forward this request to internal 192.168.0.224:1234. In this case the port is se same, but don’t need to be.
  • It is very important, that the internal network and the Beryl Network are not the same! The beryl can’t work, if you use 192.168.8.0/24 for your home network!

I really have no Idea, why I’ve used bullet points. But I am too lacy to remove them now. I hope this paints a clearer picture about what will happen.
Be aware EVERY system on the internet can reach your beryl via [WAN IP]:1234 … If there is a exploitable service is listening at this port, an attacker could get full access to your whole LAN!
This is the reason, why you should a. be aware what you are doing and b. know the risk at any time!