Virtualbox - NAT Port Forwarding

Can VM communicate with the host in NAT mode?

No, in NAT mode in VirtualBox, the virtual machine (VM) cannot directly communicate with the host unless specific configuration steps are taken.

Explanation of NAT Mode:

• VM to External Network (Internet): The VM can access the internet or any external network via the host, since VirtualBox uses the host's network interface as a gateway. However, the host and the VM are in separate network spaces, and the VM doesn't have an IP address that is directly visible to the host machine.

• VM to Host Communication: In NAT mode, the VM is isolated from the host. It can’t directly communicate with the host machine (e.g., by pinging it or accessing services running on the host) unless additional steps are taken.

How to Enable Communication Between the VM and Host in NAT Mode:

If you still need to allow communication between the VM and the host machine in NAT mode, you have a couple of options:

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1. Port Forwarding (for specific services like SSH, HTTP, etc.)

2. Using Host-Only Adapter (for full communication)

If you need full communication between the host and the VM, including the ability to ping the VM or use other network services, you should consider using Host-Only Networking instead of NAT.

• Host-Only Networking creates a network that allows the host and VM to communicate directly, but it isolates the VM from external networks (like the internet) unless you configure additional routing or port forwarding.

3. NAT Network (for VM-to-VM and Host Communication)

If you want to allow communication between multiple VMs and the host while still using NAT, you can use the NAT Network mode.

• NAT Network allows VMs to communicate with each other and access external networks (internet) via the host.
• Communication between the host and the VMs is still limited, but you can use port forwarding to access specific services running on the VMs.

To enable NAT Network:

1. Create a NAT Network in VirtualBox (File > Preferences > Network).
2. Set the VM to use NAT Network in the Settings > Network > Adapter 1.
3. Configure port forwarding if needed.

 

sudo ufw allow 22/tcp   # For SSH

 

 

This blog post assumes that you are running the latest version of VirtualBox, which at the time of this writing is version 7.0.6. You can check the version by going to Help → About.

The goal of this blog will be to set up port forwarding so that open ports on your VM can be accessed from the host system. The VM needs to be shut down prior to performing these steps.

Highlight the VM you will be working with and select Settings → Network. You should see the network adapter screen.

The “Adapter 1” tab should be showing. Verify that the “Attached to” field is set to “NAT”. Now, click the Advanced drop down and then click the Port Forwarding button.

With port forwarding, we effectively make a “tunnel” from a port on the host system to a port on the VM. When you access the port on the host, your traffic will automatically get forwarded to the defined port on the VM.

We are going to create two entries, one for SSH and another for HTTPS. Click the green plus symbol on the right, and create two entries using the following values:

Name: HTTPS
Protocol: TCP
Host IP: 127.0.0.1
Host Port: <A port not in use on the host, 10443 or similar>
Guest IP: <IP assigned to VM, usually 10.0.2.15>
Guest Port: 443

Name: SSH
Protocol: TCP
Host IP: 127.0.0.1
Host Port: <A port not in use on the host, 10022 or similar>
Guest IP: <IP assigned to VM, usually 10.0.2.15>
Guest Port: 22

Your port forwarding rules should look like this:

 

Click the “Adapter 2” tab. Enable this adapter and set the “Attached to” field to be “Host-only Adapter”.

Once complete, click the “OK” button. You can now start up the VM. Once the VM boots, you should be able to access SSH and HTTPS via the loopback address. For example, if I used the same “Host Port” defined above, I can point my Web browser at:

https://127.0.0.1:10443

and connect to the Web server running on the VM. If I SSH to:

ssh username@127.0.0.1:10022

I’ll connect to the SSH server running on the VM.