In this article I wrote down a step-by-step walkthrough on creating an isolated environment for hosting services, using a VLAN setup. By using a VLAN and setting up a firewall we can isolate the virtual server from your primary private network, layering an additional shield of security to your setup. As an example we’ll use a virtual machine (VM) hosting a database service as our primary example.

Ubiquiti VLAN Configuration

1. Create a VLAN

• Log into your UniFi Controller.
• Navigate to the “Settings” (gear icon) at the bottom left.
• Under “Networks”, click on “Create New Network”.
• Provide a name for the network, for instance, “Public VLAN”.
• Set “Purpose” to “Corporate”.
• Assign a VLAN ID of “10”.
• Define the subnet as 10.0.0.1/24.
• Configure the DHCP range if required and save these settings.

2. Firewall Rules for VLAN Traffic

• Proceed to “Routing & Firewall” within the settings.

• Select “Firewall” and then “LAN IN”.

• Set up a rule that permits only PostgreSQL traffic:

  • Name: Allow PostgreSQL to WAN
  • Action: Accept
  • Source: Public VLAN
  • Destination: Any
  • Ports: 5432 (PostgreSQL’s default port)

• Create rules that block all traffic from the VLAN to other local networks:

  • Name: Block VLAN to all LANs
  • Action: Drop
  • Source: Public VLAN
  • Destination: All other local networks/VLANs

3. Port Forwarding

• Navigate to “Routing & Firewall” and select “Port Forwarding”.

• Click on the “+ Create New Rule” or “Add New Port Forward Rule” button, which should open a new window or pane for rule creation.

• Name: Give the rule a descriptive name, e.g., “PostgreSQL Remote Access”.

• Enabled: Make sure this is toggled on.

• Rule Applied: Set to “After Predefined Rules”

• WAN Interface: Usually set to “All” unless you have multiple WANs and prefer a specific one.

• Original IP: Leave as “Any” to allow access from any external IP or specify a range/IP if you have a static IP where you’ll be connecting from.

• Original Port: Set to the PostgreSQL default port, “5432”.

• Forward IP: Enter the IP address of the machine where PostgreSQL is running, in this case, the VM’s IP, 10.0.0.2.

• Forward Port: Again, set this to “5432”.

• Protocol: PostgreSQL typically uses TCP, so set this to “TCP”. If there are any reasons to believe you need both TCP and UDP, you can set it to “Both”, but this is usually not necessary for PostgreSQL.

Proxmox VM Configuration

1. VM Creation or Modification

Now lest assign our newly created VLAN to a VM. Either initiate a new VM or select an existing one.

• Access the Proxmox web interface.
• During the setup or via the “Network” menu for an existing VM:
  • Set the Bridge, you can use your default, typically vmbr0.
  • Assign the VLAN Tag to “10”.
  • Ensure the firewall is activated.
  • IPv4/CIDR: 10.0.0.2/32
  • Gateway: 10.0.0.1
• Once the VM is started or rebooted, it should automatically acquire the assigned static IP.

Testing the Configuration

1. Verify the IP Address

• In Proxmox, access the VM’s console.
• Execute the ifconfig command to ensure that the IP address 10.0.0.2 has been correctly assigned.

2. Test Connectivity

• In the same console, check internet access by pinging an external website: ping www.daangeijs.nl.
• Subsequently, attempt to ping a device from your private network. This ping should fail, verifying that the VM is isolated from the private network.

There you go! You’ve successfully set up a VLAN and isolated a VM within it. You can now host services on this VM and access them from the internet, while keeping your private network secure.