Forwarding guest ports

You may ocassionally find the need to expose VM ports to the internet, as would be the case when hosting some game server that only runs on Windows. The easiest way to get this done is to just use libvirt-hook-qemu.

Installing the hook

1. Begin by installing the prerequisites:

   sudo xbps-install git make

2. Clone the repo and change directory into it:

   git clone https://github.com/saschpe/libvirt-hook-qemu
   cd libvirt-hook-qemu

3. Install the hook with:

   sudo make install

4. You will have to restart the libvirt daemon next. Ensure no VM is running, then run:

   sudo sv restart libvirtd

Configuring the ports

The file with the port forwarding configuration for the VM can be found at /etc/libvirt/hooks/hooks.json, so you can open it with e.g.:

sudo nano /etc/libvirt/hooks/hooks.json

Make sure to read the comments, they document the configuration pretty well. The usual steps it takes for configuring the ports are:

1. Replacing example-guest-vm-name-please-change with name of the target VM.

2. Replacing private_ip with the IP shown by the NIC interface of the VM.

3. Removing or commenting out source_ip.

4. Finally, setting the port_map or port_range to your desired configuration.

Note that the configuration is only applied when the VM starts, so it is necessary to restart it for changes to take effect.

Uninstalling the hook

If at any point you wish to uninstall the hook, simply do:

sudo make uninstall

This will remove it while leaving configuration files intact.