[SOLVED] Filtered minecraft server port on Ubuntu vm

[TehN00bz]

Hi!

So I've been trying out proxmox on one of my old laptops to learn but I can't seem to get port forwarding to work correctly.

I'm trying to forward port 25565 on an Ubuntu server LTS 20.04 VM

-I've disabled ufw on the VM and pve-firewall on the server
-I can connect to the VM locally
-Port checking sites say that the port is open but when I use nmap, the port is shown as filtered

I feel like I'm missing some key configuration but I'm not that knowledgeable at networking and I'd appreciate some help. Thanks!

 

[Dunuin]

Did you setup port-forwarding in your router?

 

[TehN00bz]

Did you setup port-forwarding in your router?

Yup, for some reason the modem shows the device name but it's configured to the right IP address

 

[Dunuin]

And you can connect to the minecraft server running inside docker container from another Host in your LAN (so port forwarding of Docker is working too)?

Make sure that you port-forward your router to the IP and port of your Docker VM and not of the IP/port your docker container is using.

 

[TehN00bz]

And you can connect to the minecraft server running inside docker container from another Host in your LAN (so port forwarding of Docker is working too)?

Make sure that you port-forward your router to the IP and port of your Docker VM and not of the IP/port your docker container is using.

Well, that's the name of the machine but the server isn't running in a docker container because it was a pain to deal with so the minecraft server is running directly on Ubuntu

 

[TehN00bz]

Solution:

I figured it out! I was trying to access the server from the public IP address from my local network which seems to be something I can't do. I used my phone tether to test if someone outside the network can access the server and it works just fine!

 

[Milkwyrm]

Sounds like you need NAT reflection enabled on your Router. then you can use the external address internally. Something that may well not be supported on your device. For instance, I use Opnsense, and from their help pages:

NAT reflection: When a client on the internal network tries to access another client, but using the external IP instead of the internal one (which would the most logical), NAT reflection can rewrite this request so that it uses the internal IP, in order to avoid taking a detour and applying rules meant for actual outside traffic.