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Source NAT

Source NAT (SNAT) allows instances in a private network tier within a VPC to communicate with external networks (e.g., the internet) using a public IP address. When a VM sends outbound traffic, the source IP address is replaced with a Source NAT IP, ensuring secure, managed access without exposing the internal IP addresses.

This section outlines the steps to acquire a public IP and configure it for Source NAT with a specific VM using the Cloud Management Portal.

What is Source NAT?​

  • Source NAT rewrites the source IP of outbound traffic from a private IP (VM) to a public IP.

  • It enables outbound internet connectivity for instances that do not have Static NAT or public IP assignment.

  • A default Source NAT IP is automatically allocated when a VPC is created, mainly used for remote VPN access.

  • Additional public IPs can be acquired and configured for SNAT and Port Forwarding.

Prerequisites​

Ensure the following before proceeding:

  • You have a running VM inside a VPC network.

  • Your VPC has available public IPs or the ability to acquire new ones.

  • The public IP used for SNAT is not already associated with another tier or NAT configuration.

1. Accessing the VPC Section :​

  • Log in to your Cloud Management Portal using your authorized credentials.

  • From the left navigation pane, go to:

    Network → VPC

  • You will see a list of all existing VPC networks associated with your cloud account.

  • Identify the VPC you want to configure and click on its name.

2. Open VPC Configuration :​

  • On the VPC overview page, click the Configure button.
  • This opens the VPC configuration interface.

3. Access Public IP Management :​

  • In the left sidebar under Router, click on Public IP Addresses.
  • This page shows the list of all public IPs acquired within this VPC.

Note: By default, one Source NAT IP is allocated at VPC creation. It is used only for remote VPN access and is not available for VM NAT services like port forwarding.

4. Acquire a New Public IP (if needed) :​

  • If there are no free public IPs, or if you wish to dedicate a new IP for SNAT:

    • Click on the Acquire New Public IP button.
  • A confirmation dialog will appear. Check the acknowledgment box and click Yes to proceed.
  • A new public IP will be added to the list. All newly acquired public IPs are marked as Source NAT IPs by default.

5. Source NAT IP via Port Forwarding :​

  • From the list of public IPs, click on the newly acquired IP address.

  • On the public IP configuration page, navigate to the Port Forwarding tab.

  • Click Add VM to start configuring the rule.

6. Configure Port Forwarding Rule :​

  • In the rule creation form, fill out the following fields:

    • Private Start Port / End Port : The internal port(s) on the VM.

    • Public Start Port / End Port : The external port(s) accessible via the public IP.

    • Protocol : Choose between TCP or UDP.

    • Description : Add a meaningful description for this rule.

  • Click Add VM & Configure to proceed.

7. Select VM and Confirm Tier :​

  • In the next window:

    • Select the network tier where the VM resides.

    • Choose the specific VM from the listed instances.

  • Click Configure to complete the process.

  • Your VM is now associated with the Source NAT IP and will be able to access external networks with proper port forwarding in place.

Important Notes :​

  • Once a public IP is used for one network tier, it cannot be reused for another tier within the same VPC.

  • Ensure the correct Access Control Lists (ACLs) are in place to manage allowed traffic.