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Azure waf nsg

Azure waf nsg

But in the real world, you should lock down network access. In the world of Azure, all network security begins with an NSG. Each backend pool member will be listed here. Otherwise, you will get a warning saying:. Unable to retrieve health status data. Next, I need to allow application traffic. In my example, the WAF is for internal usage. Here is a sample rule:. To be honest, this one caught me out until I reasoned what the cause was.

That puzzled me, and searches led me nowhere useful. And then I realized:. Yes, it has priority But we will be putting in a rule at to prevent all connections, overriding the rule that allows everything from VirtualNetwork — which includes all subnets in the virtual network and all peered virtual networks. Now we will override the default NSG rules that allow all communications to the subnet from other subnets in the same VNet or peered VNets.

This rule should have the lowest possible user-defined priority, which is Why am I using the lowest possible priority?

This is classic good firewall rule practice. General rules should be low priority, and specific rules should be high priority. The more general, the lower. The more specific, the higher. What do those need to look like?

Your email address will not be published. This site uses Akismet to reduce spam. Learn how your comment data is processed. Associate the NSG with the subnet.

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Otherwise, you will get a warning saying: Unable to retrieve health status data. Two questions arise: Is this secure? They are presented to clients as a single IP. This rule should have the lowest possible user-defined priority, which is Why am I using the lowest possible priority? The low priority deny rule will block all other communications. Job done! Please follow and like us:.

Leave a Reply Cancel reply Your email address will not be published.Back-end health : Application Gateway provides the capability to monitor the health of the servers in the back-end pools through the Azure portal and through PowerShell. You can also find the health of the back-end pools through the performance diagnostic logs. Logs : Logs allow for performance, access, and other data to be saved or consumed from a resource for monitoring purposes.

Metrics : Application Gateway has several metrics which help you verify that your system is performing as expected.

Locking Down Network Access to the Azure Application Gateway/Firewall

This article has been updated to use the new Azure PowerShell Az module. You can still use the AzureRM module, which will continue to receive bug fixes until at least December Application Gateway provides the capability to monitor the health of individual members of the back-end pools through the portal, PowerShell, and the command-line interface CLI.

You can also find an aggregated health summary of back-end pools through the performance diagnostic logs. The back-end health report reflects the output of the Application Gateway health probe to the back-end instances. When probing is successful and the back end can receive traffic, it's considered healthy. Otherwise, it's considered unhealthy. This port range is required for Azure infrastructure communication.

They are protected locked down by Azure certificates. Without proper certificates, external entities, including the customers of those gateways, will not be able to initiate any changes on those endpoints. In the portal, back-end health is provided automatically. Back-end pool name, port, back-end HTTP settings name, and health status are shown. Valid values for health status are HealthyUnhealthyand Unknown.

You can use different types of logs in Azure to manage and troubleshoot application gateways. You can access some of these logs through the portal.

azure waf nsg

You can learn more about the different types of logs from the following list:. Logs are available only for resources deployed in the Azure Resource Manager deployment model. You cannot use logs for resources in the classic deployment model. For a better understanding of the two models, see the Understanding Resource Manager deployment and classic deployment article. Activity logging is automatically enabled for every Resource Manager resource.

You must enable access and performance logging to start collecting the data available through those logs. To enable logging, use the following steps:. Note your storage account's resource ID, where the log data is stored. You can use any storage account in your subscription.

You can use the Azure portal to find this information. Note your application gateway's resource ID for which logging is enabled. You can use the portal to find this information. Activity logs do not require a separate storage account. The use of storage for access and performance logging incurs service charges.Web applications are increasingly targeted by malicious attacks that exploit commonly known vulnerabilities.

SQL injection and cross-site scripting are among the most common attacks. The WAF automatically updates to include protection against new vulnerabilities, with no additional configuration needed. You can create multiple policies, and they can be associated with an Application Gateway, to individual listeners, or to path-based routing rules on an Application Gateway.

This way, you can have separate policies for each site behind your Application Gateway if needed. That means this feature is subject to Microsoft's Supplemental Terms of Use. Application Gateway operates as an application delivery controller ADC. It offers Transport Layer Security TLSpreviously known as Secure Sockets Layer SSLtermination, cookie-based session affinity, round-robin load distribution, content-based routing, ability to host multiple websites, and security enhancements.

The combination protects your web applications against common vulnerabilities. And it provides an easy-to-configure central location to manage. Protect your web applications from web vulnerabilities and attacks without modification to back-end code. Protect multiple web applications at the same time. An instance of Application Gateway can host up to 40 websites that are protected by a web application firewall.

Monitor attacks against your web applications by using a real-time WAF log. Security Center provides a central view of the security state of all your Azure resources.

Customize WAF rules and rule groups to suit your application requirements and eliminate false positives. This Policy is where all of the managed rules, custom rules, exclusions, and other customizations such as file upload limit exist. Application Gateway supports three rule sets: CRS 3. These rules protect your web applications from malicious activity. For more information, see Web application firewall CRS rule groups and rules.

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Application Gateway also supports custom rules. With custom rules, you can create your own rules, which are evaluated for each request that passes through WAF.

These rules hold a higher priority than the rest of the rules in the managed rule sets.

Azure - Application Gateway Part - 1

If a set of conditions is met, an action is taken to allow or block. The geomatch operator is now available in public preview for custom rules. Please see geomatch custom rules for more information.

The geomatch operator for custom rules is currently in public preview and is provided with a preview service level agreement. Certain features may not be supported or may have constrained capabilities. For more information on custom rules, see Custom Rules for Application Gateway.

A managed Bot protection rule set can be enabled for your WAF to block or log requests from known malicious IP addresses, alongside the managed ruleset. Intelligent Security Graph powers Microsoft threat intelligence and is used by multiple services including Azure Security Center. Bot protection rule set is currently in public preview and is provided with a preview service level agreement.

If Bot Protection is enabled, incoming requests that match Malicious Bot's client IPs are logged in the Firewall log, see more information below. You may access WAF logs from storage account, event hub, or log analytics. It is recommended that you run a newly deployed WAF in Detection mode for a short period of time in a production environment.

This provides the opportunity to obtain firewall logs and update any exceptions or custom rules prior to transition to Prevention mode. This can help reduce the occurrence of unexpected blocked traffic.Azure Application Gateway consists of several components that you can configure in various ways for different scenarios.

This article shows you how to configure each component. This image illustrates an application that has three listeners. Both listen on port This article has been updated to use the new Azure PowerShell Az module.

You can still use the AzureRM module, which will continue to receive bug fixes until at least December An application gateway is a dedicated deployment in your virtual network.

Within your virtual network, a dedicated subnet is required for the application gateway. You can have multiple instances of a given application gateway deployment in a subnet. You can also deploy other application gateways in the subnet. But you can't deploy any other resource in the application gateway subnet. Azure also reserves five IP addresses in each subnet for internal use: the first four and the last IP addresses. For example, consider 15 application gateway instances with no private front-end IP.

You need at least 20 IP addresses for this subnet: five for internal use and 15 for the application gateway instances. Consider a subnet that has 27 application gateway instances and an IP address for a private front-end IP. In this case, you need 33 IP addresses: 27 for the application gateway instances, one for the private front end, and five for internal use. This size gives you 11 usable IP addresses.

But there are some restrictions:. This port range is required for Azure infrastructure communication. These ports are protected locked down by Azure certificates.

External entities, including the customers of those gateways, can't communicate on these endpoints.

azure waf nsg

Outbound internet connectivity can't be blocked. Default outbound rules in the NSG allow internet connectivity. We recommend that you:. Put the following restrictions on the subnet in this order of priority:.

Using UDRs on the Application Gateway subnet might cause the health status in the back-end health view to appear as Unknown. It also might cause generation of Application Gateway logs and metrics to fail. We recommend that you don't use UDRs on the Application Gateway subnet so that you can view the back-end health, logs, and metrics. For example, you can set up a UDR in the Application Gateway subnet to point to a firewall appliance for packet inspection.

But you must make sure that the packet can reach its intended destination after inspection. Failure to do so might result in incorrect health-probe or traffic-routing behavior. This includes learned routes or default 0. An incorrect configuration of the route table could result in asymmetrical routing in Application Gateway v2.

Logging and metrics could also be affected. Sometimes the default gateway route 0. This breaks management plane traffic, which requires a direct path to the Internet.This article has been updated to use the new Azure PowerShell Az module. You can still use the AzureRM module, which will continue to receive bug fixes until at least December It offers various layer 7 load-balancing capabilities for your applications.

This service is highly available, scalable, and fully managed by Azure.

azure waf nsg

For a full list of supported features, see Introduction to Application Gateway. It supports capabilities such as TLS termination, cookie-based session affinity, and round robin for load-balancing traffic. See supported backend resources. Application Gateway is available in all regions of global Azure. Redirection is supported. See Application Gateway redirect overview.

See the order of listener processing. Or find it in the portal, on the overview page for the application gateway. If you're using internal IP addresses, find the information on the overview page.

Keep-Alive timeout governs how long the Application Gateway will wait for a client to send another HTTP request on a persistent connection before reusing it or closing it. But the DNS name associated with the application gateway doesn't change over the lifetime of the gateway. See Application Gateway subnet size considerations.

In addition to multiple instances of a given Application Gateway deployment, you can provision another unique Application Gateway resource to an existing subnet that contains a different Application Gateway resource. Yes, but only specific scenarios. For more information, see Application Gateway configuration overview. See Modifications to a request. Changes to instance size or count aren't disruptive, and the gateway remains active during this time.

Most deployments that use the v2 SKU take around 6 minutes to provision. However it can take longer depending on the type of deployment. For example, deployments across multiple Availability Zones with many instances can take more than 6 minutes.

However, it is strongly recommended that you move to v2 to take advantage of the feature updates in that SKU. For more information, see Autoscaling and Zone-redundant Application Gateway v2.

The Application Gateway v1 SKU supports high-availability scenarios when you've deployed two or more instances. Azure distributes these instances across update and fault domains to ensure that instances don't all fail at the same time. The v1 SKU supports scalability by adding multiple instances of the same gateway to share the load.

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The v2 SKU automatically ensures that new instances are spread across fault domains and update domains.Network Security Group NSG is the main tool you need to use to enforce and control network traffic rules at the networking level. In the diagram below, both VNETs and NSGs reside in a specific layer in the Azure overall security stack, where NSGs, UDR, and network virtual appliances can be used to create security boundaries to protect the application deployments in the protected network.

In one of my recent engagement with my partners, I had the opportunity to test NSG power, facing some limitations and gaining some good knowledge and experiences I would like to share with you. For some of them, I will include links to existing documentations since published before this blog post. If you played even only minimally with NSG, you immediately realized that you need to think very carefully about your subnets and virtual network architecture: even if you can also assign NSG to the VM network interface NIC level, probably you will want to use subnets as your level of granularity see below for more details.

Since it is not easy and immediate to change subnet structure, if you already deployed VMs in there, my first suggestion is to design your VNET architecture before and also according to your NSG needs. Once you have designed your network topology, you need to think about the architecture of the boundaries you want to enforce and probably how your DMZ will look like. In this case, you need to answer at least the questions below, I fetched from an excellent article see URL belowwritten by Jon Ormondthat I strongly encourage you to read:.

It is highly recommended to use ARM for new deployments, and then use ASM only when necessary to support existing environments. Also consider that if you want to do some advanced stuff, probably you will not be able to do that in Azure Portal GUI.

This is what I found in my activities, be aware of the following:. Binding NSG to the individual VMs by NIC is powerful, but you may quickly lose control of the complexity of your deployment since would be hard to track and maintain.

For outgoing traffic is obviously the converse. The picture below should even clarify this concept more: you can see how rules are evaluated for network packets, once again remember that you need to evaluate this diagram two times: once for subnet level NSG rules, and once for NIC level NSG rules.

Notice in the output that there are three inbound and three outbound rules. Rules are assigned a priority, and while the default rules cannot be deleted, they can be overridden by rules with higher priority.

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Then, what is not included here? Tools are also very important and final results may differ greatly depending on your choice. In this case the tool you have chosen has taken care of ensure that, since your VM is exposed to the Internet, access is restricted and secured. On the other side, if you use PowerShell instead, you will not be prompted or required to create NSG: it us under your responsibility to create proper NSG and rules.

If your intention is to harden network security of your environment, be very careful with adding NSG rules that will block everything, instead proceed incrementally in a test environment until you will be satisfied with the results. This specific rule has been added to defaults to do not break previous Azure VM behaviors, I have seen many customers and partners that restricted this adding a new rule, with higher priority lower numberto deny Internet connection partially or totally.

This is legitimate, but deny all the Internet traffic maybe dangerous and cause your VM to fail if, for example, you are using VM Extensions as explained in the article below:. The case above is only one, but there may be other situations where the applications and services installed inside your environment may need to access, for example, other Azure services like Azure SQL DB or Azure Storage resources.

Unfortunately, today there is no tag in NSG to identify Azure datacenter IP ranges, they can vary over time and by regions, then how to selectively block Internet outbound traffic without compromising Azure access? My colleague Keith Mayer built a nice solution as described in the article below.

Since Azure datacenter ranges are published here, you can use his work to automate NSG creation, using PowerShell, based on this piece of information that Microsoft periodically update. Another useful example is Azure Diagnostic: if you need to enable this feature for your VMs, you cannot deny all outbound traffic, otherwise the agent running inside the Virtual Machine will not be able to connect.

The list can continue with SQL Server VM agents for automated patching and backup to Azure blob storage: if you enable these extensions, you need to permit outbound Internet access from these VMs.

Azure Web Application Firewall on Azure Application Gateway

After digging into the details of objects and making some experiment, I created a piece of PowerShell code to achieve that:. You can use the same technique to change the assigned NSG.

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Diagnostic and logs are an important part, especially if you need to troubleshoot unexpected behaviors that may be related to NSG mis-configurations.Combined with the isolation and additional scaling provided by App Service Environments, this provides an ideal environment to host business critical web applications that need to withstand malicious requests and high volume traffic. A high-level diagram of the setup would look like the following image:.

To configure an App Service Environment, refer to our documentation on the subject. Barracuda has a detailed article on deploying its WAF on a virtual machine in Azure. But because we want redundancy and not introduce a single point of failure, you want to deploy at least two WAF instance VMs into the same Cloud Service when following these instructions.

Use a browser to browse to the management endpoint on your Cloud Service. If your Cloud Service is called test. You should see a login page like the following image that you can log in using credentials you specified in the WAF VM setup phase.

Once you log in, you should see a dashboard like the one in the following image that presents basic statistics about the WAF protection.

Clicking on the Services tab lets you configure your WAF for services it is protecting. For more details on configuring your Barracuda WAF, see their documentation. Depending on how your applications are configured and what features are being used in your App Service Environment, you need to forward traffic for TCP ports other than 80 andfor example, if you have IP TLS setup for an App Service app.

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If your application is available in multiple regions, then you would want to load balance them behind Azure Traffic Manager. To do so, you can add an endpoint in the Azure portal using the Cloud Service name for your WAF in the Traffic Manager profile as shown in the following image.

If your application requires authentication, ensure you have some resource that doesn't require any authentication for Traffic Manager to ping for the availability of your application. You can configure the URL on the Configuration page in the Azure portal as shown in the following image:. To forward the Traffic Manager pings from your WAF to your application, you need to set up Website Translations on your Barracuda WAF to forward traffic to your application as shown in the following example:.

Here's a sample Powershell command for performing this task for TCP port Make sure to update the IP address in the Network Resource group once you do so. You may also leave feedback directly on GitHub.