Step by Step Azure NAT Gateway – Static Outbound Public IP address #ANG #NAT #WVD #Azure #Security #Cloud #MVPBuzz #AzOps #ITPRO #VirtualNetworks #PowerShell

There a several ways on using an external IP in Azure, What method to use is up to you. Remember there is no good or wrong but only different opinions or insights on how to use it.

Public IP addresses allow Internet resources to communicate inbound to Azure resources. Public IP addresses also enable Azure resources to communicate outbound to Internet and public-facing Azure services with an IP address assigned to the resource. The address is dedicated to the resource, until it is unassigned by you. If a public IP address is not assigned to a resource, the resource can still communicate outbound to the Internet, but Azure dynamically assigns an available IP address that is not dedicated to the resource.

Some of the resources you can associate a public IP address resource with are:

  • Virtual machine network interfaces
  • Internet-facing load balancers
  • VPN gateways
  • Application gateways
  • Azure Firewall
  • NAT Gateway

Matching SKUs must be used for load balancer and public IP resources. You can’t have a mixture of basic SKU resources and standard SKU resources. You can’t attach standalone virtual machines, virtual machines in an availability set resource, or a virtual machine scale set resources to both SKUs simultaneously.

Virtual Network NAT (network address translation) simplifies outbound-only Internet connectivity for virtual networks. When configured on a subnet, all outbound connectivity uses your specified static public IP addresses. Outbound connectivity is possible without load balancer or public IP addresses directly attached to virtual machines. NAT is fully managed and highly resilient.

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So this is only for the Outbound connection. why not use the Resource group IP this is also “static” ? using this IP means that al VM’s must be in the same resource group and when the resource group changed the IP is also changing.

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NAT is compatible with standard SKU public IP address resources or public IP prefix resources or a combination of both. You can use a public IP prefix directly or distribute the public IP addresses of the prefix across multiple NAT gateway resources. NAT will groom all traffic to the range of IP addresses of the prefix. Any IP whitelisting of your deployments is now easy.

So How to implement this. a step by step guide. GUI and powershell Looking at my demo setup, There are 2 vm’s both in a different Resource group.

Setting up the NAT gateway is done by 3 tabs to fill in the name and what vnet to use

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We add a new NAT gateway.

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We create a new resource group and choose NAT gateway name.

The Timeout we leave this on 4 min for now.

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We configure an external IP and with a standard SKU. Basic is not supported.

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the next step is choose the External outbound IP pool minimal is 2 and max is 256. this is not needed but only if you want to have a pool of External IP’s else it just go the one external ip

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you can select max 2 prefixes

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Configure which subnets of a virtual network should use this NAT gateway. Subnets with Basic load balancers or virtual machines that are using a Basic public IP are not compatible and cannot be used.
Note: While you do not have to complete this step to create a NAT gateway, the NAT gateway will not be functional until you have added at least one subnet. You can also add and reconfigure which subnets are included after creating the NAT gateway.

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in the last step we tag the NAT gateway to a subnet. When checking the VM’s on this subnet for the outbound IP ( remember the VM does not need a public IP on the network card)

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Here I have 2 VM’s getting both an IP from the prefix

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If there is only a small prefix then both machines will get the same external outbound IP

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With this time flow it recycles the External IP, depending on the scope and usage.

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So in just a few steps you can use a useful gateway for all your outbound traffic.

Building this in Powershell is also easy. I use a semi automatic script as I want to choose my network. but you can change this to a fixed network if you want.

remember this will need the az.network latest module. in the old modules there is no get-AzNatGateway command. without this the posh is not working.

First we have some parameters

# Set the variables for the NAT Gateway.
$rg = ‘rg-rsm-natgw001’
$Location = ‘Westeurope’
$sku = ‘Standard’
$PublicIpname = ‘pup-rsm-natgw001’
$Publicprefixname = ‘pxp-rsm-natgw001’
$NatGatewayname=’gwn-rsm-natgateway001′

#create Rsource group
New-AzResourceGroup -Name $rg -Location $Location 

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First we make some external IP and or a range.

#create Standard SKUP public IP
$publicIP = New-AzPublicIpAddress -Name $PublicIpname -ResourceGroupName $rg -AllocationMethod Static -Location $Location -Sku $sku
$publicIP | Select-Object Name, ResourceGroupName, IpAddress, IdleTimeoutInMinutes, ProvisioningState

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With the Zone attribute you can create zone redundancy, but this is not needed for this resource.

#create  IP prefix ( how many IP’s are needed)
$publicIPPrefix = New-AzPublicIpPrefix -Name $Publicprefixname -ResourceGroupName $rg -Location $Location -PrefixLength 29

$publicIPPrefix | Select-Object Name, IPPrefix, PrefixLength, ProvisioningState

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You can skip this if you want only one external IP.

Next is creating the gateway.


#Create NAT gateway
$natGateway = New-AzNatGateway -Name $NatGatewayname -ResourceGroupName $rg -PublicIpAddress $publicIP -PublicIpPrefix $publicIPPrefix -Location $Location -Sku $sku -IdleTimeoutInMinutes 4
$natGateway  | Select-Object Name, ResourceGroupName, IdleTimeoutInMinutes , SKuText | Format-table -autosize –wrap

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Now that the Gateway is created we can add a subnet to this. I used a point an click so that I can choose the network and subnet. but you can also use a variable to do this.

$virtualNetwork = Get-AzVirtualNetwork | Out-GridView -PassThru -Title "Pick the vnet that will be used for the NAT gateway"

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$NATSubnet = Get-AzVirtualNetworkSubnetConfig -VirtualNetwork $virtualNetwork | Out-GridView -PassThru -Title "Pick the Subnet that will be used for the NAT gateway"

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$NATSubnet.NatGateway = $natGateway
$virtualNetwork | Set-AzVirtualNetwork

The network is chosen and the subnet is selected.

In the Azure portal you can see the result.

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Author: Robert Smit [MVP]

Robert Smit is Senior Technical Evangelist and is a current Microsoft MVP in Clustering as of 2009. Robert has over 20 years experience in IT with experience in the educational, health-care and finance industries. Robert’s past IT experience in the trenches of IT gives him the knowledge and insight that allows him to communicate effectively with IT professionals who are trying to address real concerns around business continuity, disaster recovery and regulatory compliance issues. Robert holds the following certifications: MCT - Microsoft Certified Trainer, MCTS - Windows Server Virtualization, MCSE, MCSA and MCPS. He is an active participant in the Microsoft newsgroup community and is currently focused on Hyper-V, Failover Clustering, SQL Server, Azure and all things related to Cloud Computing and Infrastructure Optimalization. Follow Robert on Twitter @ClusterMVP Or follow his blog https://robertsmit.wordpress.com Linkedin Profile Http://nl.linkedin.com/in/robertsmit Robert is also capable of transferring his knowledge to others which is a rare feature in the field of IT. He makes a point of not only solving issues but also of giving on the job training of his colleagues. A customer says " Robert has been a big influence on our technical staff and I have to come to know him as a brilliant specialist concerning Microsoft Products. He was Capable with his in-depth knowledge of Microsoft products to troubleshoot problems and develop our infrastructure to a higher level. I would certainly hire him again in the future. " Details of the Recommendation: "I have been coordinating with Robert implementing a very complex system. Although he was primarily a Microsoft infrastructure specialist; he was able to understand and debug .Net based complext Windows applications and websites. His input to improve performance of applications proved very helpful for the success of our project

2 thoughts on “Step by Step Azure NAT Gateway – Static Outbound Public IP address #ANG #NAT #WVD #Azure #Security #Cloud #MVPBuzz #AzOps #ITPRO #VirtualNetworks #PowerShell”

  1. Thanks for the guide. However it leaves with a kind of a gap…

    In situations where Azure Firewall is used, how to implement NAT Gateway? Is it possible to use the NAT gateway to designate a public IP address to specific resources (say FTP, web server, VMs) in order that those resources are getting the same public IP address all the time? Specifically when Azure Firewall holds multiple public IP addresses?

    As far as MS Docs say, Azure Firewall is not able to designate outbound traffic to a specific public IP address (missing feature).

  2. well you can use both right the firewall and the nat gateway, or add more external ip’s to the firewall. it all depends on the pool of IP’s you are using, but it is not the vm nic ip.

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