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Asked: 2024-10-01T15:01:31+05:30

How can I prevent a virtual machine or container in Proxmox from connecting to the internet?

I’ve been diving into virtualization lately, and I’ve set up a couple of virtual machines in Proxmox for testing some software. Everything’s been running smoothly so far, but I realized I don’t want these VMs to have internet access for a specific project I’m working on. I want to ensure they stay isolated to avoid any unwanted updates or interactions with the outside world.

I’ve skimmed through the Proxmox documentation and some forums, but there are so many different setups and configurations that I’m feeling a bit overwhelmed. I mean, one minute I’m reading about bridging networks, and the next, I see references to setting up VLANs. Can someone explain in layman’s terms how to effectively cut off internet access for a VM or even a container?

I understand that there are several ways to go about this, but I’m looking for a straightforward approach. For example, should I just mess around with the network settings in the VM configuration? Or can I do something at the host level that could apply to multiple VMs? Maybe there’s a simple checkbox I need to uncheck?

Also, does anyone know if this is reversible? Like, what if I later decide I want to give these VMs internet access for testing purposes? I want to avoid a complicated redo of my settings just to make that happen.

And, while we’re at it, how does this affect things like shared folders or file transfers? Will I still be able to move files between my host and the VM without an internet connection?

I appreciate any tips or tricks you can share. I just want to create a safe little environment for my testing without worrying about accidental updates or downloads messing things up. Thanks in advance for your help!

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    2 Answers

    1. To isolate your virtual machines (VMs) and prevent them from accessing the internet, you can start by modifying the network settings in Proxmox. One straightforward way to achieve this is by setting the VM’s network adapter to “No Network Device” or disconnecting the existing network interface in the VM configuration settings. This can be done by going to the “Hardware” tab of your VM, selecting the network interface, and choosing “Remove” or disabling it. Alternatively, if you want to keep the network interface for local communication but disable internet access, you can change the VM’s network configuration to connect it to an isolated virtual network, which will effectively deny internet access while still allowing inter-VM communications. For multiple VMs, this can be efficiently managed by creating a new virtual bridge that does not connect to any external network.

      Making these changes is reversible; you can later enable internet access by reconnecting the network interface or changing the bridge settings back to your public network. As for file transfers or shared folders, these should still function normally through a shared storage or local network setups, as long as the network settings allow for it. If you require file transfers between your host and VMs, you might consider using shared folders or local network access that does not rely on an internet connection. In summary, with a few changes to your VM’s network configuration, you can create a safe environment for your testing without unintended internet interactions.

    2. How to Cut Off Internet Access in Proxmox VMs

      If you want to isolate your VMs in Proxmox from the internet, there are a few simple methods to achieve this. Here’s a straightforward approach:

      Method 1: Disable Network Access in VM Configuration

      1. Go to your Proxmox web interface.
      2. Select the VM you want to modify.
      3. Click on Hardware from the left menu.
      4. Find the Network Device (usually named net0) and click Edit.
      5. In the settings, you can either:
        • Uncheck the option that allows it to connect to a bridge, or
        • Simply change the Bridge setting to none or a nonexistent bridge.
      6. Click OK to save your changes.

      Method 2: Use Isolated Networks

      If you need a more advanced setup or want to apply the same setting to multiple VMs, creating an isolated virtual network might be better:

      1. In the Proxmox web interface, go to Datacenter → Network.
      2. Add a new Linux Bridge (let’s say it is vmbr1).
      3. Don’t assign any physical NIC to that bridge, keeping it isolated.
      4. Assign your VMs’ network interfaces to this new bridge.

      Is It Reversible?

      Yes, cutting off internet access is completely reversible! When you decide you want to restore internet access, just go back to the VM’s network settings and reassign it to a connected bridge (like vmbr0, which connects to your physical network).

      File Transfers and Shared Folders

      You’re good to go! You can still set up shared folders or use other methods like SCP or SFTP to transfer files between your host and the VM, as long as those services are accessible via the internal network. Just keep in mind that while the VM is isolated from the internet, it will still be able to communicate with your host machine.

      Final Notes

      By following these steps, you can create a safe, isolated testing environment for your VMs. Just remember, whenever you need to change the settings back, it is usually just a matter of a few clicks. Good luck with your testing!