Is there any approach to replace NAT Gateway?

Question

We currently have a NAT Gateway configured to manage outbound traffic for one of our Azure App Services. However, since the NAT Gateway is one of the most expensive resources in our setup, we're looking for a more cost-effective alternative that can serve the same purpose. Any suggestions or guidance would be greatly appreciated.

Answer 1

Hi Khaleel Shaik,

In addition to Luke Murray response,

we recommend replacing the NAT Gateway with a lightweight Linux VM acting as a NAT instance. This setup uses VNet Integration, a User Defined Route (UDR), and standard Linux NAT capabilities. while maintaining control over outbound IPs from Azure App Services

Do follow configure-virtual-machine-software

1. Enable VNet Integration

In the App Service, go to Networking → VNet Integration

Integrate with a VNet and select a dedicated subnet

2. Provision the NAT VM

Create a Linux VM (Ubuntu/Debian recommended) in the same VNet or a peered VNet

Assign a Standard SKU Static Public IP

• Enable IP forwarding: example in the document above enable-ip-forwarding-in-the-operating-system
• 

3. Configure NAT with iptables

4. Create a User Defined Route (UDR)

• Create a route table and a route for all traffic:

az network route-table create \
                 --resource-group test-rg \
                 --name route-table-nat-hub \
                 --location eastus2

Associate the route table with the subnet used by VNet Integration

5. Update NSG Rules (if any)

• Ensure that traffic is allowed:
  • From App Service subnet → NAT VM (private IP)
  • From NAT VM → Internet
  • From Internet → NAT VM (optional, for testing/monitoring)

6. we can test it by Deploy an endpoint in the App Service that calls: test-nat-gateway-from-spoke-one

https://whatsmyip.com

This should return the static public IP of the NAT VM, confirming that traffic is routing correctly.

If you have any further assistant, do let me know.