Prescaling in Azure Firewall is now generally available
Azure Firewall protects your applications and workloads with cloud-native network security that automatically scales based on your traffic needs. Today, we’re excited to announce the general availability of prescaling in Azure Firewall – a new capability that gives you more control and predictability over how your firewall scales. Why pre-scaling? Today, Azure Firewall automatically scales in response to real-time traffic demand. For organizations with predictable traffic patterns – such as seasonal events, business campaigns, holidays, or planned migrations – the ability to plan capacity in advance can provide greater confidence and control. That’s where prescaling comes in. With prescaling, you can: Plan ahead– Set a baseline number of firewall capacity units to ensure capacity is already in place before demand rises. Stay flexible – Define both minimum and maximum capacity unit values, so your firewall always has room to grow while staying within your chosen bounds. See clearly – Monitor capacity trends with a new observed capacity metric and configure alerts to know when scaling events occur. You can think of it as adding extra checkout counters before a holiday rush – when the customers arrive, you’re already prepared to serve them without delays or bottlenecks. Example scenarios E-commerce sales events – Scale up before a holiday shopping promotion to handle the surge in online buyers. Workload migrations – Ensure sufficient capacity is ready during a large data or VM migration window. Seasonal usage – For industries like education, gaming, or media streaming, pre-scale ahead of known peak seasons. Getting started in Azure Portal Navigate to your Azure Firewall resource in the Azure Portal. Select Scaling options in settings. By default, every Azure Firewall starts in autoscaling mode. To enable prescaling, simply switch to pre-scaling mode in the Azure Portal and configure your desired capacity range: Minimum capacity: 2 or higher. Maximum capacity: up to 50, depending on your needs. Monitor the scaling behavior with the observed capacity metric. Billing and availability Pre-scaling uses a new Capacity Unit Hour meter. Charges apply based on the number of firewall instances you configure. Standard: $0.07 per capacity unit hour Premium: $0.11 per capacity unit hour ✨ Next steps Prescaling gives you predictable performance and proactive control over your firewall, helping you confidently handle the traffic patterns that matter most to your business. 🚀 Try prescaling today and share your feedback with the team. Learn more about how to configure and monitor this feature in the Azure Firewall prescaling documentation.How Azure network security can help you meet NIS2 compliance
With the adoption of the NIS2 Directive EU 2022 2555, cybersecurity obligations for both public and private sector organizations have become more strict and far reaching. NIS2 aims to establish a higher common level of cybersecurity across the European Union by enforcing stronger requirements on risk management, incident reporting, supply chain protection, and governance. If your organization runs on Microsoft Azure, you already have powerful services to support your NIS2 journey. In particular Azure network security products such as Azure Firewall, Azure Web Application Firewall WAF, and Azure DDoS Protection provide foundational controls. The key is to configure and operate them in a way that aligns with the directive’s expectations. Important note This article is a technical guide based on the NIS2 Directive EU 2022 2555 and Microsoft product documentation. It is not legal advice. For formal interpretations, consult your legal or regulatory experts. What is NIS2? NIS2 replaces the original NIS Directive 2016 and entered into force on 16 January 2023. Member states must transpose it into national law by 17 October 2024. Its goals are to: Expand the scope of covered entities essential and important entities Harmonize cybersecurity standards across member states Introduce stricter supervisory and enforcement measures Strengthen supply chain security and reporting obligations Key provisions include: Article 20 management responsibility and governance Article 21 cybersecurity risk management measures Article 23 incident notification obligations These articles require organizations to implement technical, operational, and organizational measures to manage risks, respond to incidents, and ensure leadership accountability. Where Azure network security fits The table below maps common NIS2 focus areas to Azure network security capabilities and how they support compliance outcomes. NIS2 focus area Azure services and capabilities How this supports compliance Incident handling and detection Azure Firewall Premium IDPS and TLS inspection, Threat Intelligence mode, Azure WAF managed rule sets and custom rules, Azure DDoS Protection, Azure Bastion diagnostic logs Detect, block, and log threats across layers three to seven. Provide telemetry for triage and enable response workflows that are auditable. Business continuity and resilience Azure Firewall availability zones and autoscale, Azure Front Door or Application Gateway WAF with zone redundant deployments, Azure Monitor with Log Analytics, Traffic Manager or Front Door for failover Improve service availability and provide data for resilience reviews and disaster recovery scenarios. Access control and segmentation Azure Firewall policy with DNAT, network, and application rules, NSGs and ASGs, Azure Bastion for browser based RDP SSH without public IPs, Private Link Enforce segmentation and isolation of critical assets. Support Zero Trust and least privilege for inbound and egress. Vulnerability and misconfiguration defense Azure WAF Microsoft managed rule set based on OWASP CRS. Azure Firewall Premium IDPS signatures Reduce exposure to common web exploits and misconfigurations for public facing apps and APIs. Encryption and secure communications TLS policy: Application Gateway SSL policy; Front Door TLS policy; App Service/PaaS minimum TLS. Inspection: Azure Firewall Premium TLS inspection Inspect and enforce encrypted communication policies and block traffic that violates TLS requirements. Inspect decrypted traffic for threats. Incident reporting and evidence Azure Network Security diagnostics, Log Analytics, Microsoft Sentinel incidents, workbooks, and playbooks Capture and retain telemetry. Correlate events, create incident timelines, and export reports to meet regulator timelines. NIS2 articles in practice Article 21 cybersecurity risk management measures Azure network controls contribute to several required measures: Prevention and detection. Azure Firewall blocks unauthorized access and inspects traffic with IDPS. Azure DDoS Protection mitigates volumetric and protocol attacks. Azure WAF prevents common web exploits based on OWASP guidance. Logging and monitoring. Azure Firewall, WAF, DDoS, and Bastion resources produce detailed resource logs and metrics in Azure Monitor. Ingest these into Microsoft Sentinel for correlation, analytics rules, and automation. Control of encrypted communications. Azure Firewall Premium provides TLS inspection to reveal malicious payloads inside encrypted sessions. Supply chain and service provider management. Use Azure Policy and Defender for Cloud to continuously assess configuration and require approved network security baselines across subscriptions and landing zones. Article 23 incident notification Build an evidence friendly workflow with Sentinel: Early warning within twenty four hours. Use Sentinel analytics rules on Firewall, WAF, DDoS, and Bastion logs to generate incidents and trigger playbooks that assemble an initial advisory. Incident notification within seventy two hours. Enrich the incident with additional context such as mitigation actions from DDoS, Firewall and WAF. Final report within one month. Produce a summary that includes root cause, impact, and corrective actions. Use Workbooks to export charts and tables that back up your narrative. Article 20 governance and accountability Management accountability. Track policy compliance with Azure Policy initiatives for Firewall, DDoS and WAF. Use exemptions rarely and record justification. Centralized visibility. Defender for Cloud’s network security posture views and recommendations give executives and owners a quick view of exposure and misconfigurations. Change control and drift prevention. Manage Firewall, WAF, and DDoS through Network Security Hub and Infrastructure as Code with Bicep or Terraform. Require pull requests and approvals to enforce four eyes on changes. Network security baseline Use this blueprint as a starting point. Adapt to your landing zone architecture and regulator guidance. Topology and control plane Hub and spoke architecture with a centralized Azure Firewall Premium in the hub. Enable availability zones. Deploy Azure Bastion Premium in the hub or a dedicated management VNet; peer to spokes. Remove public IPs from management NICs and disable public RDP SSH on VMs. Use Network Security Hub for at-scale management. Require Infrastructure as Code for all network security resources. Web application protection Protect public apps with Azure Front Door Premium WAF where edge inspection is required. Use Application Gateway WAF v2 for regional scenarios. Enable the Microsoft managed rule set and the latest version. Add custom rules for geo based allow or deny and bot management. enable rate limiting when appropriate. DDoS strategy Enable DDoS Network Protection on virtual networks that contain internet facing resources. Use IP Protection for single public IP scenarios. Configure DDoS diagnostics and alerts. Stream to Sentinel. Define runbooks for escalation and service team engagement. Firewall policy Enable IDPS in alert and then in alert and deny for high confidence signatures. Enable TLS inspection for outbound and inbound where supported. Enforce FQDN and URL filtering for egress. Require explicit allow lists for critical segments. Deny inbound RDP SSH from the internet. Allow management traffic only from Bastion subnets or approved management jump segments. Logging, retention, and access Turn on diagnostic settings for Firewall, WAF, DDoS, and Application Gateway or Front Door. Send to Log Analytics and an archive storage account for long term retention. Set retention per national law and internal policy. Azure Monitor Log Analytics supports table-level retention and archive for up to 12 years, many teams keep a shorter interactive window and multi-year archive for audits. Restrict access with Azure RBAC and Customer Managed Keys where applicable. Automation and playbooks Build Sentinel playbooks for regulator notifications, ticket creation, and evidence collection. Maintain dry run versions for exercises. Add analytics for Bastion session starts to sensitive VMs, excessive failed connection attempts, and out of hours access. Conclusion Azure network security services provide the technical controls most organizations need in order to align with NIS2. When combined with policy enforcement, centralized logging, and automated detection and response, they create a defensible and auditable posture. Focus on layered protection, secure connectivity, and real time response so that you can reduce exposure to evolving threats, accelerate incident response, and meet NIS2 obligations with confidence. References NIS2 primary source Directive (EU) 2022/2555 (NIS2). https://eur-lex.europa.eu/eli/dir/2022/2555/oj/eng Azure Firewall Premium features (TLS inspection, IDPS, URL filtering). https://learn.microsoft.com/en-us/azure/firewall/premium-features Deploy & configure Azure Firewall Premium. https://learn.microsoft.com/en-us/azure/firewall/premium-deploy IDPS signature categories reference. https://learn.microsoft.com/en-us/azure/firewall/idps-signature-categories Monitoring & diagnostic logs reference. https://learn.microsoft.com/en-us/azure/firewall/monitor-firewall-reference Web Application Firewall WAF on Azure Front Door overview & features. https://learn.microsoft.com/en-us/azure/frontdoor/web-application-firewall WAF on Application Gateway overview. https://learn.microsoft.com/en-us/azure/web-application-firewall/overview Examine WAF logs with Log Analytics. https://learn.microsoft.com/en-us/azure/application-gateway/log-analytics Rate limiting with Front Door WAF. https://learn.microsoft.com/en-us/azure/web-application-firewall/afds/waf-front-door-rate-limit Azure DDoS Protection Service overview & SKUs (Network Protection, IP Protection). https://learn.microsoft.com/en-us/azure/ddos-protection/ddos-protection-overview Quickstart: Enable DDoS IP Protection. https://learn.microsoft.com/en-us/azure/ddos-protection/manage-ddos-ip-protection-portal View DDoS diagnostic logs (Notifications, Mitigation Reports/Flows). https://learn.microsoft.com/en-us/azure/ddos-protection/ddos-view-diagnostic-logs Azure Bastion Azure Bastion overview and SKUs. https://learn.microsoft.com/en-us/azure/bastion/bastion-overview Deploy and configure Azure Bastion. https://learn.microsoft.com/en-us/azure/bastion/tutorial-create-host-portal Disable public RDP and SSH on Azure VMs. https://learn.microsoft.com/en-us/azure/virtual-machines/security-baseline Azure Bastion diagnostic logs and metrics. https://learn.microsoft.com/en-us/azure/bastion/bastion-diagnostic-logs Microsoft Sentinel Sentinel documentation (onboard, analytics, automation). https://learn.microsoft.com/en-us/azure/sentinel/ Azure Firewall solution for Microsoft Sentinel. https://learn.microsoft.com/en-us/azure/firewall/firewall-sentinel-overview Use Microsoft Sentinel with Azure WAF. https://learn.microsoft.com/en-us/azure/web-application-firewall/waf-sentinel Architecture & routing Hub‑spoke network topology (reference). https://learn.microsoft.com/en-us/azure/architecture/networking/architecture/hub-spoke Azure Firewall Manager & secured virtual hub. https://learn.microsoft.com/en-us/azure/firewall-manager/secured-virtual-hubAzure DDoS Protection now supports QUIC protocol — Securing the future of HTTP/3 traffic
The internet’s transport layer is undergoing one of its most significant evolutions in decades. QUIC (Quick UDP Internet Connections) — the protocol underpinning HTTP/3 — is rapidly becoming the default for high performance, secure communication on the web. From YouTube streaming to WhatsApp messaging, QUIC is already powering billions of connections daily. Recognizing both its potential and its unique security challenges, Microsoft has now integrated full QUIC mitigation capabilities into Azure DDoS Protection. This protection is enabled by default — no configuration required — ensuring that customers adopting HTTP/3 can do so with confidence. What is QUIC and why it matters QUIC was originally developed by Google and standardized by the IETF in 2021 (RFC 9000). Unlike traditional HTTP/2 over TCP, QUIC runs over UDP port 443, combining transport and security layers into a single handshake. This allows a secure, encrypted connection to be established in just one round trip — or even zero round trips for repeat connections. Technical advantages of QUIC include: Integrated TLS 1.3 — Encryption is built into the protocol, eliminating the need for separate TLS negotiation. Multiplexed streams without head of line blocking — Independent streams mean packet loss in one stream doesn’t stall others. Connection migration — QUIC connections survive IP address changes, ideal for mobile devices switching between Wi-Fi and cellular. Faster recovery from loss — QUIC uses packet numbers instead of TCP sequence numbers, improving loss detection and retransmission. These features make QUIC ideal for latency sensitive workloads such as video streaming, online gaming, and real-time collaboration tools. The DDoS challenge for QUIC: While QUIC’s design improves performance and security, its reliance on UDP introduces a distinct threat profile that goes beyond traditional UDP floods. QUIC’s handshake, encryption model, and connection identifiers create attack surfaces unique to the protocol. Key QUIC‑specific DDoS vectors include: Initial Packet Floods with Fake Handshakes Attackers send large volumes of QUIC Initial packets containing incomplete or malformed TLS Client Hello messages. This forces the server to allocate cryptographic resources for each bogus attempt, consuming CPU and memory. Connection ID Exhaustion QUIC uses Connection IDs to maintain state across IP changes. Attackers can rapidly cycle through random Connection IDs to bypass per‑IP rate limits. This can overwhelm connection tracking tables. Version Negotiation Abuse Attackers send unsupported or random QUIC version numbers to trigger repeated version negotiation responses from the server. This consumes bandwidth and processing without establishing a valid session. Malformed Frame Injection QUIC frames (STREAM, ACK, CRYPTO, etc.) can be deliberately malformed to trigger parsing errors or excessive error handling. Unlike generic UDP payloads, these require QUIC‑aware inspection to detect. Amplification via Retry Packets QUIC Retry packets can be abused in reflection attacks if the server responds with larger payloads than the request. Attackers spoof victim IPs to direct amplified traffic toward them. Why this is different from generic UDP floods: Generic UDP attacks typically rely on raw packet volume or reflection from open services. QUIC attacks exploit protocol‑level behaviors — handshake processing, version negotiation, and Connection ID handling — that require stateful, QUIC‑aware mitigation. Traditional UDP filtering cannot distinguish between a legitimate QUIC Initial packet and a crafted one designed to exhaust resources. Azure DDoS Protection — QUIC mitigation [built-in]: Azure DDoS Protection now supports QUIC mitigation by default. This enhancement applies to all customers automatically — no opt-in or no manual tuning is required. Technical capabilities include: Protocol Compliance Validation — Ensures QUIC packets conform to RFC specifications, including fixed bit checks, version enforcement, and valid Connection ID lengths. Initial Packet Verification — Validates that QUIC initial packets contain a proper TLS Client Hello with Server Name Indication (SNI), blocking spoofed or incomplete handshakes. Source & Destination Rate Limiting — Controls excessive connection attempts per 4tuple (source IP, destination IP, source port, destination port). Global Limit IDs (GLID) — Applies connection and packet rate limits globally across the mitigation platform. Retry Authentication — Issues a cryptographic cookie challenge to verify client authenticity before allowing session establishment. Packet Rate Limiting by Connection ID — Limits both long header (initial) and short header (post handshake) packet rates to prevent floods. Malformed Packet Filtering — Drops packets with unsupported frames, invalid versions, or missing headers. Version Pinning — Prevents downgrade attacks by enforcing negotiated QUIC versions. All existing Layer 4 protections for UDP traffic — such as flood detection, anomaly scoring, and adaptive thresholds — are fully applied to QUIC. Real-world impact: Without effective mitigation, QUIC based services are highly susceptible to a range of disruptive threats. UDP floods can quickly overwhelm servers, consume resources and render applications unresponsive. Amplification attacks, which exploit the stateless nature of UDP, can multiply inbound traffic by factors of ten to a hundred, creating massive spikes that cripple performance. Such attacks often lead to high packet loss, degraded user experiences, and service interruptions. They can also drive-up infrastructure costs significantly, as organizations are forced to handle large volumes of malicious traffic that consume bandwidth and processing power. With Azure DDoS Protection in place, these risks are proactively addressed. Intelligent rate limiting and packet filtering mechanisms stop floods before they impact service availability. Spoofed packet blocking prevents reflection attacks from ever reaching the application layer. The result is a consistently reliable, low latency connection for QUIC enabled applications, even under hostile network conditions. By scrubbing malicious traffic before it reaches customer workloads, Azure also helps reduce operational costs, ensuring that resources are spent serving legitimate users rather than absorbing attack traffic. Who benefits from QUIC DDoS mitigation: The benefits of QUIC aware DDoS protection extend across industries and use cases. Web applications and APIs built on HTTP/3 gain the performance advantages of QUIC without inheriting its security risks. Streaming platforms such as YouTube or Twitch can deliver high quality, uninterrupted video experiences to millions of viewers, even during attempted network disruptions. Messaging and VoIP services like WhatsApp, Discord, and Zoom maintain crystal clear communication and low latency, which are critical for user satisfaction. Online gaming platforms, where milliseconds matter, can preserve smooth gameplay and prevent lag spikes caused by malicious traffic. Financial services and real-time transaction systems also stand to benefit, as they can maintain secure, uninterrupted operations in environments where downtime or delays could have significant business and compliance implications. Looking ahead: Microsoft is committed to continuously strengthening QUIC protection within Azure DDoS Protection. Efforts are already underway to expand mitigation capabilities ensuring broader coverage across the global network and to detect and neutralize threats faster and with greater precision, adapting to the evolving tactics of attackers. Just as importantly, Microsoft is actively gathering feedback from customers and internal teams to refine mitigation strategies, ensuring that QUIC protection remains both robust and aligned with real world usage patterns. These ongoing enhancements will help customers confidently adopt and scale QUIC based services, knowing that their performance and security are safeguarded by default. Conclusion: QUIC is the future of fast, secure internet communication — and Azure DDoS Protection is ready for it. With always-on, default-enabled QUIC mitigation, Azure customers can confidently adopt HTTP/3 without worrying about the unique DDoS risks that come with UDP based protocols. Your applications stay fast. Your users stay connected. Your infrastructure stays protected.Monitoring web application traffic for configuring rate limit on Azure Front Door WAF
Introduction Azure Web Application Firewall (WAF) is a cloud-native service that actively protects web applications from common vulnerabilities and exploits. It also supports custom rules that allow fine-grained control over traffic. Among these custom rules is the rate-limiting feature available in both Azure Application Gateway and Azure Front Door. Rate limiting helps mitigate denial-of-service (DoS) attacks, prevents abuse from misconfigured clients sending excessive requests, and controls traffic from specific geographies. By limiting requests per client in a set time window, WAF keeps your app available and responsive even under heavy load. While rate limiting is a powerful tool for safeguarding web applications, some users struggle with configuring appropriate thresholds and durations. These two values often require tuning based on actual traffic patterns. Without proper planning or visibility into real traffic patterns, rate limit settings often end up being: Too strict – Blocking legitimate users and degrading user experience. Too lenient – Failing to stop abusive or malicious traffic. This blog is the first in a two-part series designed to help users configure rate limiting in Azure Web Application Firewall (WAF). In this first part, we focus on Azure Front Door WAF and demonstrate how to use diagnostic logs to make informed, data-driven decisions about rate limit thresholds and durations. By analyzing real traffic patterns, you can configure rate limits that strike the right balance between security and usability, protecting your application without disrupting legitimate users. Understanding rate limiting in Azure Front Door WAF At its core, rate limiting is a mechanism that restricts the number of requests a client can make to a web application within a specified period. This helps prevent issues like brute-force login attacks, automated bots scraping data, or sudden traffic spikes. Azure Front Door WAF applies rate limiting through custom rules that monitor incoming requests according to specific match conditions. Key characteristics of rate limiting in Azure Front Door WAF include: Duration: Can be set to 1 or 5 minutes. Threshold: Number of requests allowed in the time window. Customizability match conditions: You can match based on country (geolocation), IP address (remote address or socket address) request URI, HTTP method, and more. Action: What to do when the threshold is exceeded e.g., deny, log, redirect, JS Challenge (preview), CAPTCHA (preview). Below is an example of a rate limit rule configured in Azure Front Door WAF: Using diagnostic logs to configure WAF rate limiting To configure effective rate limiting policies in Azure Front Door WAF, it is important to understand how users are accessing your application. Diagnostic logs from Azure Front Door provide this visibility. In this section, we’ll walk through: Enabling diagnostic logs Querying traffic patterns with KQL Using insights to define smart thresholds and durations Enable diagnostic logs In Azure Front Door: Go to your Front Door profile. Under Monitoring, select Diagnostic settings. Click + Add diagnostic setting. Add a new setting to capture: FrontDoor Access Log – request level data. FrontDoor WebApplicationFirewall Log – WAF rule matches. Send logs to: Log Analytics workspace (recommended for querying), Storage account, or Event Hub. Save the settings. When configuring rate limit rules in Azure Front Door WAF, you can choose either a 1-minute or 5-minute time window. While both options are supported, using a 5-minute window with a higher threshold can improve detection accuracy by reducing false positives. Rate limiting is applied per socket IP - the source IP as seen by Azure Front Door. If there's another CDN or proxy in front of Front Door, this IP may not represent the original client, which can affect how rate limits are enforced. Please refer to Web application firewall rate limiting for Azure Front Door | Microsoft Learn. Analyze traffic behavior with KQL With diagnostic logs flowing into your log analytics workspace, you can begin to understand actual request volumes, IP behavior, and trends across time. These insights form the basis for defining effective rate limits. Query 1: Average requests per IP (5-minute intervals) This first query provides the average number of requests each client IP sends over 5-minute windows. It helps establish a baseline of expected activity per user. Understanding the average request rate helps you distinguish between normal and abnormal behavior. It’s your starting point for setting a rate limit that won’t block legitimate users. AzureDiagnostics | where Category == "FrontDoorAccessLog" | summarize RequestsPerIP = count() by clientIp_s, bin(TimeGenerated, 5m) | summarize AvgRequestsPerIP = avg(RequestsPerIP) by bin(TimeGenerated, 5m) | order by TimeGenerated asc Usage: Set your initial rate limit slightly above the observed average to allow for minor bursts while still preventing abuse. The screenshot below shows the average number of requests per IP in 5-minute intervals from our Azure Front Door demo environment within a 7-day period. Most intervals fall between 1 to 5 requests per IP, indicating normal user behavior. However, there are occasional spikes, such as 15.5 requests at 4:10 PM and a significant burst of 459 requests at 4:15 AM. This highlights the importance of using real data to set thresholds. While a baseline of 20–30 requests per 5 minutes would cover typical traffic, it would still catch outlier spikes like these that may indicate abuse or automation. Query 2: Max requests seen from a client IP (5-minute window) This query surfaces the maximum number of requests observed from any individual IP address in a single 5-minute time window. This helps you understand peak load behavior, which could be from a legitimate spike or a potential abuse/bot. AzureDiagnostics | where Category == "FrontDoorAccessLog" | summarize RequestsPerIP = count() by clientIp_s, bin(TimeGenerated, 5m) | summarize MaxRequestsPerIP = max(RequestsPerIP) by clientIp_s | order by MaxRequestsPerIP desc Usage: Use this to define an upper threshold for rate limiting. To avoid overfitting outliers, consider setting your limit near the 95th percentile of these max values. The screenshot below shows the results of the KQL query executed in my demo environment using Azure Front Door diagnostic logs within a 7-day period. As observed, the most active IP (35.X.X.X) recorded a peak of 459 requests within a 5-minute window, which is significantly higher than the rest. The second highest IP peaked at 106 requests, and most of the client IPs fell well below 30 requests per 5 minutes. This distribution highlights an important insight: while most users exhibit moderate request behavior, a few outliers can generate large bursts. These outliers could be misconfigured clients, aggressive bots, or potential abuse cases. When configuring rate limits, it’s advisable to base your threshold not on the absolute maximum (459), but rather on a statistical percentile such as the 90th or 95th percentile. In this case, a reasonable threshold might be around 120–150 requests per 5 minutes, allowing headroom for legitimate high-traffic users while still blocking abnormal spikes. Query 3: Most active IP per country (Geo-aware limit tuning) This query identifies the top-requesting IP address per country for each 5-minute window. Seeing regional traffic patterns allows you to detect suspicious activity from specific geographies or apply geo-based rate limits. Azure Front Door: AzureDiagnostics | where Category == "FrontDoorAccessLog" | summarize RequestCount = count() by bin(TimeGenerated, 5m), clientCountry_s, clientIp_s | summarize arg_max(RequestCount, clientIp_s) by TimeGenerated, clientCountry_s | project TimeGenerated, clientCountry_s, clientIp_s, RequestCount | order by TimeGenerated asc, clientCountry_s asc Usage: Use this to justify stricter thresholds for high-traffic countries or create region-specific custom WAF rules. The screenshot below shows the output of the geo-based query, which identifies the most active IP address per country in 5-minute intervals. As observed, some IPs consistently generate higher request volumes than others, indicating regional traffic concentration or potential anomalies. This pattern can help inform geo-specific rate limiting strategies, where regions with higher activity may warrant stricter thresholds or additional monitoring to mitigate localized abuse without impacting global user experience. Query 4: Request trends per URI segment This query breaks down requests by the first segment of the URI path (e.g., /api, /assets). It helps identify which parts of your app are most accessed. Azure Front Door: AzureDiagnostics | where Category == "FrontDoorAccessLog" | extend Path = tostring(parse_url(requestUri_s).Path) | extend FirstSegment = extract("^/([^/]+)", 0, Path) | summarize RequestCount = count() by FirstSegment, bin(TimeGenerated, 5m) | order by TimeGenerated asc, RequestCount desc Usage: Endpoints such as /login or /register are often targets for abuse. Segment-level analysis helps you target rate limits to specific parts of your app. The screenshot below shows the request distribution across the first URI segment (or resource) in 5-minute intervals. From the data, it’s clear that certain endpoints such as those serving static files (e.g., /styles.css) or known paths like /favicon.ico have consistent but low traffic. However, there are sudden spikes, such as 27 requests to /styles.css and 56 requests to /checkout.html, which could indicate automation, scraping, or testing behavior. Tracking usage by URI segment helps you identify which parts of your app are under heavy or suspicious load. You can use this insight to apply URI-specific rate limiting rules, especially for sensitive or high-traffic paths (e.g., /checkout, /login, /debug). This minimizes the risk of abuse without throttling static content or safe endpoints. Query 5: Average requests per full URI This query calculates the average number of requests per full URI across all 5-minute intervals. It helps identify high-traffic endpoints. Endpoints with consistently high traffic may need dedicated rate limits. Azure Front Door: AzureDiagnostics | where Category == "FrontDoorAccessLog" | summarize RequestsPerUri = count() by requestUri_s, bin(TimeGenerated, 5m) | summarize AvgRequestsPerUri = avg(RequestsPerUri) by requestUri_s | order by AvgRequestsPerUri desc Usage: Use this to create path-specific rules; for example, /login may need a stricter threshold than /homepage. The screenshot below shows the results of the query, highlighting which full URIs receive the highest average number of requests over 5-minute intervals. The results show frequent access to specific assets (e.g., /favicon.ico, /styles.css), REST API endpoints, and one suspicious XSS injection attempt with unusually high traffic. This insight helps identify abuse patterns, automated scans, or popular resources, guiding you to apply rate limits more precisely either globally or per path to protect critical or vulnerable endpoints. Guidance and Considerations The KQL queries and thresholds shared in this blog are intended as guidance based on common patterns and demo environments. Traffic behavior varies across applications, and you should validate results against your own environment and adjust thresholds accordingly. Always test custom rules in Detection mode before enforcing them in Prevention mode to avoid disrupting legitimate traffic. It’s also important to consider the scalability of the application or backend service behind Azure Front Door. Rate limiting controls traffic, but if your app runs on a single instance or doesn’t scale well, it may still fail under load. As a best practice, ensure your services can auto scale or handle spikes gracefully in tandem with WAF rate limiting rules. Conclusion Configuring effective rate limiting in Azure Front Door WAF is not just about setting arbitrary thresholds. It requires understanding how your application is accessed and where traffic patterns indicate potential abuse or anomalies. By leveraging diagnostic logs and analyzing real-world traffic with KQL, you can create rate limit rules that are both protective and practical. This data-driven approach helps you to reduce noise, prevent misuse, and maintain a smooth experience for legitimate users. References What is Azure Web Application Firewall on Azure Front Door? | Microsoft Learn Web application firewall custom rule for Azure Front Door | Microsoft Learn Web application firewall rate limiting for Azure Front Door | Microsoft Learn Azure Web Application Firewall monitoring and logging | Microsoft LearnIntroducing the new Network Security Hub in Azure
Background: Since its launch in 2020, Azure Firewall Manager has supported customers in securing their networks. But the role of network security has since evolved, from a foundational requirement to a strategic priority for organizations. Today, organizations must protect every endpoint, server, and workload, as attackers continually search for the weakest link. Over the years, we’ve heard consistent feedback about the importance of centralized management, easier service discovery, and streamlined monitoring across their network security tools. These capabilities can make the difference between a minor incident and a major breach. That’s why we’re excited to introduce a new, unified Network Security hub experience. This updated hub brings together Azure Firewall, Web Application Firewall, and DDoS Protection—enabling you to manage, configure, and monitor all your network security services in one place. While Azure Firewall Manager offered some of this functionality, the name didn’t reflect the broader scope of protection and control that customers need. With this new experience, Firewall Manager has expanded into the Network Security Hub, making it easier to discover, configure, and monitor the right security services with just a few clicks. The result: less time navigating, more time securing your environment. What you’ll notice: Streamlined navigation: Whether you search for Azure Firewall, Web Application Firewall, DDoS Protection, or Firewall Manager, you’ll now be directed to the new Network Security hub. This unified entry point presents all relevant services in context—helping you stay focused and quickly find what you need, without feeling overwhelmed. Overview of services: The hub’s landing page provides a high-level view of each recommended solution, including key use cases, documentation links, and pricing details—so you can make informed decisions faster. Common scenarios: Explore typical deployment architectures and step-by-step guidance for getting started, right from the overview page. Related services: We’ve consolidated overlapping or closely related services to reduce noise and make your options clearer. The result? Fewer, more meaningful choices that are easier to evaluate and implement. New insights: We've enhanced the security coverage interface to show how many of your key resources are protected by Azure Firewall, DDoS Protection, and Web Application Firewall. Additionally, our integration with Azure Advisor now provides tailored recommendations to help you strengthen your security posture, reduce costs, and optimize Azure Firewall performance. What this means for you: No changes to Firewall Manager pricing or support: This is a user experience update only for Firewall Manager. You can continue to deploy Firewall policies and create Hub Virtual Network or Secured Virtual Hub deployments —now within the streamlined Network Security hub experience. Aligned marketing and documentation: We’ve updated our marketing pages and documentation to reflect this new experience, making it easier to find the right guidance and stay aligned with the latest best practices. Faster decision-making: With a clearer, more intuitive layout, it’s easier to discover the right service and act with confidence. Better product experience: This update brings greater cohesion to the Azure Networking portfolio, helping you get started quickly and unlock more value from day one Before: The original landing page was primarily focused on setting up Firewall Policies and Secured Virtual Hub, offering a limited view of Azure’s broader network security capabilities. After: The updated landing page delivers a more comprehensive and intuitive experience, with clear guidance on how to get started with each product—alongside common deployment scenarios to help you configure and operationalize your network security stack with ease. Before: The previous monitoring and security coverage experience was cluttered and difficult to navigate, making it harder to get a quick sense of your environment’s protection status. After: The updated Security Coverage view is cleaner and more intuitive. We've streamlined the layout and added Azure Advisor integration, so you can now quickly assess protection status across key services and receive actionable recommendations in one place. The expansion of Firewall Manager into the Network Security hub is part of a greater strategic effort to simplify and enhance the Azure Networking portfolio, ensuring better alignment with customer needs and industry best practices. You can learn more about this initiative in this blog. This shift is designed to better align with customer needs and industry best practices—by emphasizing core services, consolidating related offerings, and phasing out legacy experiences. The result is a more cohesive, intuitive, and efficient product experience across Azure Networking. 📣 If you have any thoughts or suggestions about the user interface, feel free to drop them in the feedback form available in the Network Security hub on the Azure Portal. Documentation links: Azure Networking hub page: Azure networking documentation | Microsoft Learn Scenario Hub pages: Azure load balancing and content delivery | Microsoft Learn Azure network foundation documentation | Microsoft Learn Azure hybrid connectivity documentation | Microsoft Learn Azure network security documentation | Microsoft Learn Scenario Overview pages What is load balancing and content delivery? | Microsoft Learn Azure Network Foundation Services Overview | Microsoft Learn What is hybrid connectivity? | Microsoft Learn What is Azure network security? | Microsoft LearnEnhancements to the Azure Firewall User Experience
This blog was co-authored by Abhinav Sriram, with contributions from Gopikrishna Kannan. Introduction Everyday, IT administrators face the challenge of securing networks while maintaining application uptime and performance. With a constantly evolving threat landscape and an influx of new vulnerabilities, staying ahead is no easy task. Cloud applications are increasingly leveraging AI to access critical data with reliability, and new applications are rapidly being onboarded. At the same time, organizational security requirements continue to expand in response to government regulations and customer expectations. CIOs are demanding that IT teams do more with less, and the demands can feel daunting. To meet these challenges, IT administrators need modern tools and resources that simplify operations, maintain security, and ensure application performance and compliance. The Azure Firewall team understands these operational needs and the proactive measures administrators require to minimize risk. We're excited to introduce new experiences and capabilities that streamline firewall management, making it easier to monitor, diagnose, and resolve issues quickly. Improved governance and compliance: Through Azure Policies and Azure Advisor recommendations, IT teams can maintain alignment with product and organizational standards, minimizing risk through proactive guidance. Optimized management and diagnostics: Through Azure Firewall Policy Change Tracking and the Diagnose and Solve Blade, administrators can monitor configuration changes and identify solutions to resolve issues quickly. In addition, the new user experiences for setting up a Management NIC and upcoming features like Packet Capture and Maintenance Configuration provide users with the kind of enhanced control and visibility they need for critical services like Firewall. Stay Updated with New Capabilities: The "What's New" experience in Azure Firewall Manager and the Private Preview Program keep administrators informed about updates and provide early access to new features. In this blog, we'll walk through each of these features more in-depth and explore how they assist administrators with tasks at different stages of firewall management beginning with features that bring enhanced governance and compliance to Azure Firewall. Built-In Azure Policies Azure Firewall now includes support for Azure Policy, designed to enhance governance and enforce security best practices. When administrators are initially configuring their firewalls or shortly after deployment, managing configurations across multiple firewalls to meet organizational standards can be complex and prone to oversight or error. These built-in policies simplify this process by automatically applying rules across your firewall resources and ensuring compliance with essential security and operational requirements. For example, administrators can enforce policies requiring Threat Intelligence to be enabled on all firewalls for added protection or mandating that only encrypted traffic is allowed into the environment. These policies offer a streamlined way to maintain consistent security practices, aligning firewall settings with organizational and regulatory standards. For detailed information on configuration and enforcement of these policies, see this blog. Image: Built-in Azure Policies Image: Azure Policy compliance enforcement across Firewall resources Built-In Azure Advisor Recommendations After deploying a firewall, it's essential to monitor any limitations that could impact its performance, particularly in large or complex environments with high traffic volumes. Azure Advisor, a personalized service, offers recommendations to help users optimize Azure resources across five key areas: reliability, security, operational excellence, performance, and cost. With this integration, Azure Advisor can proactively notify you if your Azure Firewall deployment is reaching any limitations, experiencing performance impacts, or has potential misconfigurations. This means you’ll be able to receive timely recommendations to address issues before they affect your network security, ensuring a seamless and secure experience. The current Azure Advisor recommendations include the following: Exceeding rule limitations on Firewall policy: Get notified if your firewall policy is reaching the maximum allowed rules, which may impact performance. Exceeding IP Group limitations on Firewall policy: Alerts for when IP groups used in your firewall policies exceed their defined limits. Exceeding Firewall Policy or Rule Collection Group size: Suggestions to optimize or restructure policies when they grow too large, potentially affecting management or performance. By leveraging these recommendations, you can maintain optimal firewall performance, address potential security risks, and reduce unnecessary costs. Stay tuned for more enhancements as we continue to add more recommendations into Azure Advisor for Azure Firewall. Policy Analytics is another Firewall capability that provides you with insights and recommendations for your environment. Image: Azure Advisor recommendation for “Firewall policy is reaching network rule limitations” Next, let’s dive into the capabilities that help with optimized management and diagnostics. Change Tracking (Preview) Azure Resource Graph (ARG) is an Azure service designed to provide efficient and performant resource exploration at scale. Azure Resource Graph (ARG) provides change analysis data for various management and troubleshooting scenarios. Users can find when changes were detected on an Azure Resource Manager (ARM) property, view property change details and query changes at scale across their subscription, management group, or tenant. ARG change analysis recently added support for RuleCollectionGroups. You can now track changes to Azure Firewall Rule Collection Groups using an Azure Resource Graph query from the Azure Portal ResourceGraphExplorer page using a query like this: Below is a sample change output. This capability can help you track changes made to your Firewall rules helping ensure accountability for a sensitive resource like a Firewall. Diagnose and Solve Blade The Diagnose and Solve problems blade is a feature in Azure that helps customers troubleshoot and solve Azure issues. It helps you explore the most common problems for your Azure Firewalls by providing quick access to service/resource health insights, automated troubleshooters, curated do-it-yourself troubleshooting guides, and additional troubleshooting tools that are all part of the self-help experience designed to help customers solve their problems even before bringing it to Microsoft support teams. To use this feature, you need to navigate to your Firewall in the Azure portal and select Diagnose and solve problems. Image: The Diagnose and Solve blade in Azure Firewall Portal This feature allows you to troubleshoot failures without needing to go through the standard process of filing a support ticket and also provides you with a summarized view of resource health and changes made to the resource in the last 72 hours. Management NIC Changes An Azure Firewall Management NIC separates Firewall management traffic from customer traffic. The firewall routes its management traffic via the dedicated AzureFirewallManagementSubnet (minimum subnet size /26) and its associated public IP address. This feature was previously called Forced Tunneling, as originally, a Management NIC was required only for Forced Tunneling. However, upcoming Firewall features will also require a Management NIC. To support any of these capabilities, you must create an Azure Firewall with the Firewall Management NIC enabled or enable it on an existing Azure Firewall. This is a mandatory requirement to avoid service disruption. To learn more, see Azure Firewall Management NIC | Microsoft Learn. Image: The updated Firewall Management Portal UX in the Create Azure Firewall workflow Lastly, let’s take a look at some of the ways in which you can stay updated with the latest going on with Azure Firewall. Updates to What’s new in Firewall Manager The “What’s new” page in Firewall Manager is kept updated with the most recent product releases across the Network Security portfolio and now easily links to the Copilot for Security integration for Azure Firewall. The Azure Firewall Plugin has four capabilities that help analysts perform detailed investigations of the malicious traffic intercepted by the IDPS feature of their firewalls across their entire fleet using natural language questions in the Copilot for Security standalone experience. To learn more about the user journey and value that Copilot can deliver, see the Azure blog. To see these capabilities in action, take a look at this Tech Community blog, and to get started, see the documentation. Image: Snapshot of the What's New user experience in Azure Firewall Manager Azure Connection Program The Azure Connection Program is an engineering feedback community for Azure customers and partners allowing you to directly engage with the product team of Azure Firewall and get early access to upcoming features like Packet Capture and Maintenance Configurations. This is an avenue where the product team actively engages with customers to get valuable feedback that can help impact the product roadmap. If you’re interested in joining and trying out new features early, please sign up here.Share Your Expertise: Help Shape Our Network Practitioner Community
Hello Azure network practitioners, We’re working on refining our understanding of network practitioner personas and building stronger community engagement strategies for networking practitioners. Your insights as an MVP are invaluable to this effort. Could you take a few minutes to complete this short survey? Your feedback will directly influence how we design future programs and resources for the community. 👉 https://forms.office.com/r/dfgXxNwQd9 Thank you for helping us make the Azure networking community even better! Best regards, Dan Product Marketing Manager, Identity & Network Access Growth
Getting Started with Azure Firewall REST API – Part II
In Part I of this series, we explored how to interact with Azure’s REST APIs using Bruno. We laid the foundation for provisioning and managing Azure Firewall using REST API, covering the core setup tasks such as creating the firewall instance, defining policies, and implementing basic rule configurations. In Part II, we take a step forward by diving into advanced configurations that are crucial for securing complex, large-scale environments. These configurations allow you to fine-tune traffic control, improve security posture, and enhance visibility into network activities. In this part, we’ll cover: Initial setup: Authentication and prerequisites Creating DNAT Rules to expose internal resources securely Enabling IDPS (Intrusion Detection and Prevention System) with Signature Overrides and Bypass Rules Using Web Categories to simplify and strengthen application rule Creating FQDN Filtering Rules to allow or deny traffic based on domain names Creating URL Filtering Rules to allow or deny traffic based on URLs Associating Multiple Public IPs with Azure Firewall for better scalability Enabling Diagnostic Settings for detailed logging and monitoring Customizing SNAT Private IP Address Ranges for precise outbound traffic control By the end of this part, you'll have a deeper understanding of how to leverage Azure Firewall’s full potential to meet real-world enterprise security needs— using REST API. Initial Setup: Authentication and Prerequisites: After downloading and setting up Bruno as the REST API client, creating a new collection as described in Part I, you will do the following: Service Principal Creation: Using Azure CLI, create a Service Principal in the correct subscription as shown below: az ad sp create-for-rbac --name "BrunoClient" --role Contributor --scopes /subscriptions/{subscription-id} Make a note of the following: App ID (client_id) Tenant ID Password (client_secret) Request a Bearer Token: Using BRUNO, get the Bearer Token using the following PUT request and details we derived from the above Service Principal Creation. POST: https://login.microsoft.com/{TenantID}/oauth2/token Body (x-www-form-urlencoded): grant_type: client_credentials client_id: {App ID} client_secret: {Password} resource: https://management.azure.com Add Authorization Header for API Requests: Once you get the Bearer Token, you need to add this to every Request as shown below: We also need to refresh the Bearer Token each time it expires and update it in the Token field for every request. Typically, it expires every 1 hour, however, the exact expiration time can vary depending on the API and its configuration. Get Your Subscription ID: Retrieve the Subscription ID for the Azure subscription where your Azure Firewall instance is deployed Using AZ CLI, get the Subscription ID to be used in the API requests: az account show --query id -o tsv Azure Firewall Configurations via REST API: In Part I of this series, we discussed how to use REST API to configure the Azure Firewall resource and the Firewall Policy. Now, let's delve into the advanced features. Configuring DNAT Rule: This example demonstrates how to configure a DNAT (Destination Network Address Translation) rule using Azure Firewall's REST API. It uses the 'FirewallPolicyNatRuleCollection' type to redirect traffic from a public IP and port to an internal FQDN and port. Request: PUT https://management.azure.com/subscriptions/{SubscriptionID}/resourceGroups/{Resourcegroupname}/providers/Microsoft.Network/firewallPolicies/{FirewallPolicyName}/ruleCollectionGroups/{RuleCollectionName}?api-version=2024-05-01 Request Body: { "properties": { "priority": 100, "ruleCollections": [ { "ruleCollectionType": "FirewallPolicyNatRuleCollection", "priority": 100, "name": "Example-Nat-Rule-Collection", "action": { "type": "DNAT" }, "rules": [ { "ruleType": "NatRule", "name": "nat-rule1", "translatedFqdn": "internalhttp.server.net", "translatedPort": "8080", "ipProtocols": [ "TCP", "UDP" ], "sourceAddresses": [ "2.2.2.2" ], "sourceIpGroups": [], "destinationAddresses": [ "{Firewall IP}" ], "destinationPorts": [ "8080" ] } ] } ] } } When the PUT request is successful, the following rule is created under DNAT Rule Collection Group as shown below: Enabling Intrusion Detection (IDPS): When using Azure Firewall Premium, enabling Intrusion Detection and Prevention (IDPS) helps monitor, detect and respond to suspicious activities, enhancing security. Below is a simple example that shows how to use the PUT method to update your Firewall policy with an IDPS configuration such as enabling it, applying signature overrides and bypassing certain trusted traffic from the IDPS rules. 💡 Note: Make sure your Azure Firewall SKU is Premium, as IDPS is only available in that tier. Request: PUT https://management.azure.com/subscriptions/{SubscriptionID}/resourceGroups//{Resourcegroupname}/providers/Microsoft.Network/firewallPolicies//{FirewallPolicyName}?api-version=2024-05-01 Request Body: { "tags": { "key1": "value1" }, "location": "westus", "properties": { "threatIntelMode": "Alert", "threatIntelWhitelist": { "ipAddresses": [], "fqdns": ["*.microsoft.com"] }, "snat": { "privateRanges": ["IANAPrivateRanges"] }, "sql": { "allowSqlRedirect": true }, "sku": { "tier": "Premium" }, "intrusionDetection": { "mode": "Alert", "configuration": { "signatureOverrides": [ { "id": "2000105", "mode": "Off" } ], "bypassTrafficSettings": [ { "name": "BypassCustomRule1", "protocol": "TCP", "sourceAddresses": ["192.168.1.0/24"], "destinationAddresses": ["10.1.1.4"], "destinationPorts": ["443"] } ] } } } } When the PUT request is successful, IDPS is enabled in Alert mode (you can also set it to Alert & Deny if needed) as shown below. In this example: Signature ID 2000105 is overridden and set to Off, which appears as Disabled in the Azure Portal. A custom bypass rule is configured to exclude specific traffic (based on source IP, destination IP, and port) from IDPS filtering. This configuration provides flexibility to fine-tune your threat detection settings while allowing exception/safe traffic to pass without inspection. Creating Web Categories Rule: Azure Firewall supports filtering outbound web traffic based on web categories, allowing administrators to block or allow access to entire categories of websites (e.g., Social Networking, Gambling, Adult Content). This provides a scalable way to enforce corporate internet usage policies without needing to specify individual domains. 💡 Note: While this feature is available in both Azure Firewall Standard and Premium, the Premium SKU offers more granular control by matching categories based on the entire URL for both HTTP and HTTPS traffic. Below is an example of how to configure a web category-based application rule using REST API: Request: PUT https://management.azure.com/subscriptions/{SubscriptionID}/resourceGroups/{Resourcegroupname}/providers/Microsoft.Network/firewallPolicies/{FirewallPolicyName}/ruleCollectionGroups/{RuleCollectionName}?api-version=2024-05-01 Request Body: Request Body: { "properties": { "priority": 200, "ruleCollections": [ { "name": "WebCategoryRuleCollection1", "ruleCollectionType": "FirewallPolicyFilterRuleCollection", "priority": 200, "action": { "type": "Deny" }, "rules": [ { "ruleType": "ApplicationRule", "name": "blockWebCategories", "description": " Block social networking and travel-related websites", "protocols": [ { "protocolType": "Https", "port": 443 }, { "protocolType": "Http", "port": 80 } ], "sourceAddresses": [ "10.0.0.0/24" ], "webCategories": [ "SocialNetworking", "Travel" ] } ] } ] } } When this PUT request is successful, the rule denies outbound traffic to websites categorized under Social Networking and Travel from the source IP address range 10.0.0.0/24, for both ports 80 & 443 as shown below: Creating FQDN Filtering Rule: In many enterprise scenarios, it’s important to control which websites users can access. Azure Firewall supports FQDN-based application rules that allow you to filter outbound traffic based on fully qualified domain names (FQDNs), such as www.instagram.com or www.expedia.com. These rules work by inspecting the Server Name Indication (SNI) field during the TLS handshake (for HTTPS traffic) or the Host header in HTTP requests. This makes it possible to apply access control without decrypting the full traffic stream — which means FQDN filtering works even without TLS inspection and is supported in both Standard and Premium SKUs. Request: PUT https://management.azure.com/subscriptions/{SubscriptionID}/resourceGroups/{Resourcegroupname}/providers/Microsoft.Network/firewallPolicies/{FirewallPolicyName}/ruleCollectionGroups/{RuleCollectionName}?api-version=2024-05-01 Request Body: { "properties": { "priority": 100, "ruleCollections": [ { "name": "AppRuleCollection1", "ruleCollectionType": "FirewallPolicyFilterRuleCollection", "priority": 100, "action": { "type": "Deny" }, "rules": [ { "ruleType": "ApplicationRule", "name": " blockSpecificFQDNs", "description": " Block specific websites by FQDN", "protocols": [ { "protocolType": "Https", "port": 443 } ], "sourceAddresses": [ "10.0.0.0/24" ], "targetFqdns": [ "www.instagram.com", "www.expedia.com" ] } ] } ] } } Creating URL Filtering Rule: If you want to control not just which domains users can access, but also specific URLs or paths within those domains, you can use the URL filtering capabilities. To enable this, you must turn on TLS inspection. With HTTPS traffic, only the domain name (e.g., example.com) is visible during the TLS handshake via SNI (Server Name Indication). The full URL path (e.g., /downloads/malware.exe) remains encrypted. To inspect it, the firewall must decrypt the traffic, apply your rules, and then re-encrypt it before forwarding it to the destination. This capability gives you granular control for scenarios like: Blocking access to specific file download paths Restricting parts of websites while allowing others Enforcing strict security policies without over blocking 💡 Note: URL path-based filtering is available only in Azure Firewall Premium. 💡 Note: Ensure TLS inspection is enabled for URL filtering to work on HTTPS traffic. Request: PUT https://management.azure.com/subscriptions/{SubscriptionID}/resourceGroups/{Resourcegroupname}/providers/Microsoft.Network/firewallPolicies/{FirewallPolicyName}/ruleCollectionGroups/{ApplicationRuleCollectionName}?api-version=2024-05-01 Request Body: Request Body: { "properties": { "priority": 100, "ruleCollections": [ { "name": "AppRuleCollection1", "ruleCollectionType": "FirewallPolicyFilterRuleCollection", "priority": 100, "action": { "type": "Deny" }, "rules": [ { "ruleType": "ApplicationRule", "name": " blockSpecificURLs", "description": " Block specific websites by FQDN", "protocols": [ { "protocolType": "Https", "port": 443 } ], "sourceAddresses": [ "10.0.0.0/24" ], "terminateTLS": true, "targetUrls": [ "www.example.com/downloads/malware.exe", "www.example.com/blockedpath/"] } ] } ] } } When this PUT request is successful, the following rule will be created to block access to the specified target FQDNs from the 10.0.0.0/24 source IP address range, as shown below: Associating Multiple Public IP’s: When managing Azure Firewall at scale, assigning multiple public IP addresses can help support higher availability and throughput, especially for SNAT or DNAT scenarios. We will walk through how to use the PUT method in Azure Firewall's REST API to deploy and associate multiple IP configurations efficiently. 💡 Note: When configuring multiple public IP addresses, ensure that you use Standard SKU public IP addresses, as Basic SKU public IPs are not supported with Azure Firewall. 💡 Note: Associating multiple public IP addresses with your firewall increases the available SNAT ports, enhancing scalability. Request: PUT https://management.azure.com/subscriptions/{SubscriptionID}/resourceGroups/{ResourceGroup}/providers/Microsoft.Network/azureFirewalls/{FirewallName}?api-version=2023-05-01 Request Body: { "location": "westus", "properties": { "ipConfigurations": [ { "name": "ipConfig1", "properties": { "publicIPAddress": { "id": "/subscriptions/{SubscriptionID}/resourceGroups/{ResourceGroupName}/ providers/Microsoft.Network/publicIPAddresses/{PublicIPName} " }, "subnet": { "id": "/subscriptions/{SubscriptionID}/resourceGroups/{ResourceGroupName}/providers/Microsoft.Network/virtualNetworks/{VnetName}/subnets/{SubnetName}" } } }, { "name": "ipConfig2", "properties": { "publicIPAddress": { "id": "/subscriptions/{SubscriptionID}/resourceGroups/{ResourceGroupName}/ providers/Microsoft.Network/publicIPAddresses/{PublicIPName} " } } } ] } } When this PUT request is successful, the specified public IP addresses will be associated with the Azure Firewall, as shown below: Enable Diagnostic Logging: Using the REST API, you can configure Azure Firewall to capture important log categories such as Application Rules, Network Rules, and DNS Proxy logs, as well as performance metrics and more. 💡 Note: A Log Analytics workspace must be set up beforehand to store the logs generated by the API configuration below. Below is an example of how to set up diagnostic settings by linking the firewall to a Log Analytics workspace: Request: PUT https://management.azure.com/subscriptions/{Subscription ID}/resourceGroups/{ResourceGroupName} /providers/Microsoft.Network/azureFirewalls/{FirewallName} /providers/microsoft.insights/diagnosticSettings/{DiagnosticsSettingsName}?api-version=2021-05-01-preview Request Body: { "properties": { "workspaceId": "/subscriptions/{SubscriptionID}/resourceGroups/{Resourcegroupname}/providers/Microsoft.OperationalInsights/workspaces/FirewallLogs", "logs": [ { "category": "AzureFirewallApplicationRule", "enabled": true, "retentionPolicy": { "enabled": false, "days": 0 } }, { "category": "AzureFirewallNetworkRule", "enabled": true, "retentionPolicy": { "enabled": false, "days": 0 } }, { "category": "AzureFirewallDnsProxy", "enabled": true, "retentionPolicy": { "enabled": false, "days": 0 } } ], "metrics": [ { "category": "AllMetrics", "enabled": true, "retentionPolicy": { "enabled": false, "days": 0 } } ], "logAnalyticsDestinationType": "Dedicated" } } When the PUT request is successful, the following logs and metrics will be enabled, and these logs will be sent to the Log Analytics Workspace specified here: Configuring SNAT Exclusions: Azure Firewall provides SNAT capability for all outbound traffic to public IP addresses. If your organization uses registered IP address ranges outside of IANA RFC 1918 or IANA RFC 6598 for private networks, Azure Firewall SNATs the traffic to one of the firewall's private IP addresses in AzureFirewallSubnet. You can configure Azure Firewall to not SNAT your public IP address range. For example, specify an individual IP address as x.x.x.x or a range of IP addresses as x.x.x.x/24. Below is an example of how to configure SNAT exclusions using REST API: Request PUT https://management.azure.com/subscriptions//{Subscription ID}/resourceGroups//{ResourceGroupName} /providers/Microsoft.Network/firewallPolicies/ {FirewallPolicyName}?api-version=2024-05-01 Request Body: { "tags": { "key1": "value1" }, "location": "westus", "properties": { "threatIntelMode": "Alert", "threatIntelWhitelist": { "ipAddresses": [ ], "fqdns": [ "*.microsoft.com" ] }, "snat": { "privateRanges": [ "1.2.3.4", "5.6.7.8”, "IANAPrivateRanges" ] }, "sql": { "allowSqlRedirect": true }, "sku": { "tier": "Premium" } } } When this PUT request is successful, the following SNAT exclusion is added alongside the default private IP ranges as shown below: Conclusion: In this part of the series, we explored how to take Azure Firewall deployments to the next level by configuring advanced features through the REST API. From setting up DNAT rules and enabling IDPS with fine-grained control, to applying web category-based filtering, FQDN filtering, URL filtering, associating multiple public IP addresses, enabling diagnostic logging, and customizing SNAT behaviors — you now have a comprehensive toolkit to secure complex environments at scale. By using the REST API, you can automate firewall management, enforce consistent security policies, and quickly adapt to changing network requirements — all critical capabilities for modern cloud-native architectures.Optimize Azure Firewall logs with selective logging
A common question from customers is whether Azure Firewall supports filtering or selecting which logs are sent to a Log Analytics workspace. This concern usually stems from the high cost of storing large volumes of data — especially in environments where the firewall inspects substantial amounts of network traffic. Azure Firewall now supports ingestion-time transformation of logs in Azure Log Analytics. This capability introduces selective and advanced filtering, giving customers more control over what data is collected and analyzed. In this blog post, we’ll explore a major new capability: Azure Firewall now supports ingestion-time transformations in Log Analytics — enabling flexible, cost-efficient logging through selective data collection. Why does it matter? For many enterprise customers, the cost of ingesting Azure Firewall logs into Log Analytics — especially at scale — can be significant. Depending on the logging mode (Basic or Analytics), ingestion costs can be substantial, potentially making it challenging to expand logging coverage across additional workloads. With ingestion-time transformations, users can filter logs by rows, columns, timestamps, and more — and apply transformations before ingestion. This ensures that only relevant and critical data is stored, helping reduce costs while retaining the necessary telemetry for analysis, threat detection, and compliance. Customer benefits Security monitoring: Log only suspicious traffic for more targeted threat detection. Cost optimization: Avoid ingesting and storing unnecessary data. Compliance: Use DCR (data collection rules) to filter and route logs to meet audit/reporting needs. Incident response: Focus on logs that matter, accelerating investigation time. Custom alerts: Build insights on top of curated, high-value logs. What are transformations in Azure Monitor? Ingestion-time transformations in Azure Monitor allow you to filter or modify incoming telemetry before it reaches your Log Analytics workspace. This happens in the cloud pipeline — after the data source (such as Azure Firewall) sends its logs, but before those logs are ingested and stored. Transformations are defined using DCR and written in Kusto Query Language (KQL). Each transformation runs against incoming records individually, letting you precisely control what gets stored – and what doesn’t. For example, you might collect only entries where the action column contains the word “deny”. That filter can be applied at ingestion time, so only those critical logs are stored. The diagram below shows how this works end-to-end, from data source to filtered ingestion. To learn more and estimate potential processing charges, refer to the official documentation. Transforming Azure Firewall logging In this section, we’ll walk through a few real-world use cases shared by customers — including how to create a DCR based on specific filtering criteria. Important: Ingestion-time transformations for Azure Firewall logs are supported only when using resource-specific logs. If you’re using legacy diagnostic settings, this capability is not available. To enable transformations, ensure your firewall is configured to send logs using the Azure Firewall resource-specific log schema. First, navigate to your Log Analytics workspace and locate the table where your Azure Firewall logs are stored (e.g., AZFWApplicationRule). Click the three-dot menu (…) on the right and select “Create transformation”. Creating a transformation is a 3 steps-process. Step 1 – Basics: Create a DCR to define how incoming data is processed and specify where it should be stored. Step 2 – Schema and transformation: Use the Transformation Editor to write a KQL query that filters the incoming data based on your criteria. Step 3 – Review: Review the table name, DCR name, and KQL query before clicking “Create”. This summary ensures everything is configured correctly. For more information on how to create a DCR, refer to the official documentation. Use case 1: Excluding alerts from low priority IDPS signatures This DCR transformation filters and reshapes incoming Azure Firewall IDPS logs before they're ingested into a Log Analytics workspace. source | where Action !contains "alert" and Severity != 3 | project TimeGenerated, Protocol, SourceIp, SourcePort, DestinationIp, DestinationPort, Action, SignatureId, Description, Severity Here's a breakdown of what it does: source: This refers to the incoming data stream — in this case, the AZFWIdpsSignature table (intrusion detection/prevention logs from Azure Firewall). | where Action !contains "alert" and Severity != 3: This line filters out any log entries where the Action contains "alert" (non-blocking detection events). Any entries where Severity equals 3 (which represents low severity events). The result: We’re keeping only more actionable or higher-severity entries that don’t just raise alerts but may involve blocks or higher-severity behaviors (e.g., deny actions, critical or warning severities). | project ...: The project statement selects and forwards only the specified columns to the Log Analytics workspace. When you run a query in your Log Analytics workspace, you’ll notice that only the specific columns defined in your transformation’s project statement are available — and they appear in the exact order specified in the query. Use case 2: Filtering out unnecessary logs (trusted or testing networks) This DCR transformation filters out log entries from specific source IP address ranges before they're ingested into Azure Monitor. In this scenario, the 10.0.200.x and 10.0.300.x ranges might represent trusted or test network segments that generate high volumes of traffic — traffic that don’t need to be logged. By excluding these IPs at ingestion time, you can significantly reduce unnecessary log volume and associated costs. source | where not( SourceIp startswith "10.0.200." or SourceIp startswith "10.0.300." ) | project TimeGenerated, Protocol, SourceIp, SourcePort, DestinationIp, DestinationPort, Action, ActionReason, Policy, RuleCollection, Rule Here's a breakdown of what it does: source: This refers to the incoming data stream — in this case, the AZFWNetworkRule table. | where not (…): Applies a filter to exclude logs that match the criteria inside. SourceIp startswith "10.0.200." and SourceIp startswith "10.0.300.": These conditions match any log where the SourceIp address falls within the 10.0.200.0/24 or 10.0.300.0/24 subnets (i.e., IPs like 10.0.200.1, 10.0.200.45, etc.). | project ...: The project statement selects and forwards only the specified columns to the Log Analytics workspace. Conclusion By leveraging ingestion-time transformations through DCR, organizations gain full control over which Azure Firewall logs are ingested in Log Analytics. This selective logging capability helps reduce noise, cut costs, and retain only high-value data for security, compliance, and operational insights. As Azure Firewall evolves these enhancements offer greater flexibility and efficiency for managing cloud-native network telemetry. Resources Azure updates | Microsoft Azure Monitoring data reference for Azure Firewall | Microsoft Learn Transformations Azure Monitor - Azure Monitor | Microsoft Learn Create a transformation in Azure Monitor - Azure Monitor | Microsoft Learn
