Using Application Private Networks


An Application Private Network (APN) is a private, encrypted network running in parallel with your standard network - essentially a VPN for your application. Every Cloud 66 application automatically has an APN installed. This allows you to:

By completely eliminating the need for your servers to have any direct, public-facing network access, your APN can make your servers exponentially more secure. APNs run on WireGuard, a very simple but very secure virtual private network (VPN) tunnel.

Configuring your APN

All Cloud 66 accounts have an APN automatically configured, and servers for each application are allocated to an APN-specific IP-range.

Each time you add servers to an application, this configuration is automatically updated to include them. The only manual configuration required is to your firewall if you need to access your APN from an external IP (see below)


If you're accessing your servers remotely via the WireGuard client, you will need to download a new config file whenever you add new servers to your app.

Allowing access via your firewall

There are two ways to allow access your APN via your firewall:

  1. Temporarily, via the APN settings page for your application
  2. Permanently via your firewall settings page

Method 1 opens your firewall to APN access for 24 hours. To do this:

This creates a 24-hour lease based on the (current) local IP address of your computer.

Method 2 requires you to manually add a firewall rule. WireGuard (and thus your APN) runs over port 51820 and uses UDP. Please follow our tutorial on adding firewall rules for help on how to do this.

Accessing your servers remotely via APN

Please follow our “Accessing servers securely” tutorial and you will be up and running in under 5 mins. All you need is:

Exchanging data between servers via APN

Servers can exchange data securely simply by using their APN-specific IP-range. All of the traffic exchanged across these IP addresses runs over the encrypted APN tunnels between servers.

This means that, even if someone gained access to the private IP range of your servers, they would be unable to decrypt this traffic without the private keys of each server (which we store in encrypted format).

APN-specific IP ranges & private DNS

Each application under your Cloud 66 account has a range of (private) IP addresses over which the APN traffic flows.

You can find the IP address of a server on your Cloud 66 Dashboard:

  1. Open the Application Overview page for the application in question
  2. Click on Network in the right-hand column
  3. Click on the Application Private Network tab
  4. You’ll see a list of your servers, each with their APN-specific IP address

Private DNS

The APN also has a private DNS based on the names of the servers that allows you to route internal application traffic more easily (without having to use IP addresses). You’ll find these domain names for each server in the same place and their APN IP addresses (see above).

The format is always: <name of server>.apn

You’ll notice that there is also a DNS entry that uses the application’s private domain name. This allows applications to communicate with each other without namespace collisions.

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