{ "api_version": "1", "kind": "dse_post", "self": "https://update.dsesecurity.com/api/v1/posts/dse-20260909-404-check-idps-private-ranges-before-interpreting-azure-firewall-traffic-direction/", "item": { "id": "https://update.dsesecurity.com/updates/dse-20260909-404-check-idps-private-ranges-before-interpreting-azure-firewall-traffic-direction/", "slug": "dse-20260909-404-check-idps-private-ranges-before-interpreting-azure-firewall-traffic-direction", "url": "https://update.dsesecurity.com/updates/dse-20260909-404-check-idps-private-ranges-before-interpreting-azure-firewall-traffic-direction/", "alternate_urls": { "markdown": "https://update.dsesecurity.com/updates/dse-20260909-404-check-idps-private-ranges-before-interpreting-azure-firewall-traffic-direction.md", "json": "https://update.dsesecurity.com/api/v1/posts/dse-20260909-404-check-idps-private-ranges-before-interpreting-azure-firewall-traffic-direction/" }, "title": "Check IDPS private ranges before interpreting Azure Firewall traffic direction", "summary": "The IDPS private-range definition determines inbound, outbound and internal classification used by direction-specific signatures.", "format": { "slug": "guide", "name": "Guide" }, "priority": { "slug": "info", "name": "Information" }, "featured": false, "image": { "theme": "network-infrastructure", "label": "Networks & infrastructure", "alt": "Resilient network core with engineered blue and gold data paths.", "card_url": "https://update.dsesecurity.com/assets/editorial/network-infrastructure-card.webp?v=1.8.20", "hero_url": "https://update.dsesecurity.com/assets/editorial/network-infrastructure-hero.webp?v=1.8.20", "social_url": "https://update.dsesecurity.com/assets/editorial/network-infrastructure-social-v2.jpg?v=1.8.20", "width": 2400, "height": 1350 }, "topics": [ { "slug": "cybersecurity", "name": "Cybersecurity", "url": "https://update.dsesecurity.com/topic/cybersecurity/" }, { "slug": "networks-infrastructure", "name": "Networks & Infrastructure", "url": "https://update.dsesecurity.com/topic/networks-infrastructure/" } ], "author": { "name": "DSE Security Editorial Team", "url": "https://update.dsesecurity.com/#editorial-team", "type": "Organization" }, "publisher": { "name": "Detection Systems & Engineering", "url": "https://dsesecurity.com/" }, "published_at": "2026-09-10T00:25:12+00:00", "modified_at": "2026-09-10T02:04:56+00:00", "reviewed_on": "2026-09-09", "reading_minutes": 2, "word_count": 224, "potentially_affected": "Azure Firewall Premium IDPS deployments with address ranges requiring explicit direction classification.", "dse_recommendation": "Compare the actual address plan with IDPS private ranges before changing signature modes.", "primary_source": { "name": "Azure Firewall Premium features implementation guide | Microsoft Learn", "url": "https://learn.microsoft.com/en-us/azure/firewall/premium-features", "published_on": null, "authority": "Microsoft Learn" }, "publishing_principles": "https://update.dsesecurity.com/updates/dse-updates-editorial-methodology/", "usage_info": "https://update.dsesecurity.com/usage/", "copyright_notice": "Copyright © 2026 Detection Systems & Engineering. All rights reserved.", "content_html": "

Source facts

\n

Azure Firewall Premium IDPS uses configured private IP ranges to classify traffic as inbound, outbound or internal. Its signatures apply to specific directions. By default, only RFC 1918 ranges are classified as private, and traffic between private ranges is considered internal.

\n

Administrators can edit, add or remove those ranges. The separate IDPS bypass list excludes selected addresses or subnets from filtering; Microsoft cautions that it is not intended as a throughput-improvement mechanism. Microsoft Learn.

\n

Applicability

\n

Identify the relevant source and destination ranges and their intended network roles. Keep IDPS direction classification separate from routing, network-rule permission and a filtering bypass.

\n

DSE recommendation

\n

DSE recommends reviewing the address plan against the private-range definition before interpreting unexpected signature behavior. Have the network and security owners agree on the intended classification, including internally used space outside the default ranges. Correct an approved classification mismatch rather than immediately disabling a signature or bypassing an entire subnet.

\n

Verification

\n

Use authorized representative flows to compare their addresses and expected direction with the current IDPS configuration and signature scope. Preserve the pre-change definition and observed results. After an approved adjustment, retest both the intended path and an adjacent path that should retain its classification. Document unresolved differences without claiming that direction classification alone proves complete threat detection.

\n

Official references

\n

Microsoft Learn: Azure Firewall Premium features implementation guide. Source retrieved September 9, 2026.

", "content_text": "Source facts\nAzure Firewall Premium IDPS uses configured private IP ranges to classify traffic as inbound, outbound or internal. Its signatures apply to specific directions. By default, only RFC 1918 ranges are classified as private, and traffic between private ranges is considered internal.\nAdministrators can edit, add or remove those ranges. The separate IDPS bypass list excludes selected addresses or subnets from filtering; Microsoft cautions that it is not intended as a throughput-improvement mechanism. Microsoft Learn.\nApplicability\nIdentify the relevant source and destination ranges and their intended network roles. Keep IDPS direction classification separate from routing, network-rule permission and a filtering bypass.\nDSE recommendation\nDSE recommends reviewing the address plan against the private-range definition before interpreting unexpected signature behavior. Have the network and security owners agree on the intended classification, including internally used space outside the default ranges. Correct an approved classification mismatch rather than immediately disabling a signature or bypassing an entire subnet.\nVerification\nUse authorized representative flows to compare their addresses and expected direction with the current IDPS configuration and signature scope. Preserve the pre-change definition and observed results. After an approved adjustment, retest both the intended path and an adjacent path that should retain its classification. Document unresolved differences without claiming that direction classification alone proves complete threat detection.\nOfficial references\nMicrosoft Learn: Azure Firewall Premium features implementation guide. Source retrieved September 9, 2026.", "content_markdown": "## Source facts\n\nAzure Firewall Premium IDPS uses configured private IP ranges to classify traffic as inbound, outbound or internal. Its signatures apply to specific directions. By default, only RFC 1918 ranges are classified as private, and traffic between private ranges is considered internal.\n\nAdministrators can edit, add or remove those ranges. The separate IDPS bypass list excludes selected addresses or subnets from filtering; Microsoft cautions that it is not intended as a throughput-improvement mechanism. [Microsoft Learn](https://learn.microsoft.com/en-us/azure/firewall/premium-features).\n\n## Applicability\n\nIdentify the relevant source and destination ranges and their intended network roles. Keep IDPS direction classification separate from routing, network-rule permission and a filtering bypass.\n\n## DSE recommendation\n\nDSE recommends reviewing the address plan against the private-range definition before interpreting unexpected signature behavior. Have the network and security owners agree on the intended classification, including internally used space outside the default ranges. Correct an approved classification mismatch rather than immediately disabling a signature or bypassing an entire subnet.\n\n## Verification\n\nUse authorized representative flows to compare their addresses and expected direction with the current IDPS configuration and signature scope. Preserve the pre-change definition and observed results. After an approved adjustment, retest both the intended path and an adjacent path that should retain its classification. Document unresolved differences without claiming that direction classification alone proves complete threat detection.\n\n## Official references\n\n[Microsoft Learn: Azure Firewall Premium features implementation guide](https://learn.microsoft.com/en-us/azure/firewall/premium-features). Source retrieved September 9, 2026." }, "json_ld": { "@context": "https://schema.org", "@graph": [ { "@type": "Organization", "@id": "https://dsesecurity.com/#organization", "name": "Detection Systems & Engineering", "alternateName": "DSE Security", "url": "https://dsesecurity.com/", "logo": { "@type": "ImageObject", "url": "https://update.dsesecurity.com/assets/dse-logo-20260812.png?v=1.8.20" } }, { "@type": "Organization", "@id": "https://update.dsesecurity.com/#editorial-team", "name": "DSE Security Editorial Team", "url": "https://update.dsesecurity.com/", "parentOrganization": { "@id": "https://dsesecurity.com/#organization" } }, { "@type": "WebSite", "@id": "https://update.dsesecurity.com/#website", "name": "DSE Updates", "alternateName": "DSE Security Knowledge Hub", "url": "https://update.dsesecurity.com/", "inLanguage": "en-US", "publisher": { "@id": "https://dsesecurity.com/#organization" }, "potentialAction": { "@type": "SearchAction", "target": { "@type": "EntryPoint", "urlTemplate": "https://update.dsesecurity.com/?q={search_term_string}" }, "query-input": "required name=search_term_string" } }, { "@type": "WebPage", "@id": "https://update.dsesecurity.com/updates/dse-20260909-404-check-idps-private-ranges-before-interpreting-azure-firewall-traffic-direction/", "url": "https://update.dsesecurity.com/updates/dse-20260909-404-check-idps-private-ranges-before-interpreting-azure-firewall-traffic-direction/", "isPartOf": { "@id": "https://update.dsesecurity.com/#website" }, "lastReviewed": "2026-09-09" }, { "@type": "BreadcrumbList", "@id": "https://update.dsesecurity.com/updates/dse-20260909-404-check-idps-private-ranges-before-interpreting-azure-firewall-traffic-direction/#breadcrumbs", "itemListElement": [ { "@type": "ListItem", "position": 1, "name": "DSE Updates", "item": "https://update.dsesecurity.com/" }, { "@type": "ListItem", "position": 2, "name": "Check IDPS private ranges before interpreting Azure Firewall traffic direction", "item": "https://update.dsesecurity.com/updates/dse-20260909-404-check-idps-private-ranges-before-interpreting-azure-firewall-traffic-direction/" } ] }, { "@type": [ "Article", "TechArticle" ], "@id": "https://update.dsesecurity.com/updates/dse-20260909-404-check-idps-private-ranges-before-interpreting-azure-firewall-traffic-direction/#article", "identifier": "https://update.dsesecurity.com/updates/dse-20260909-404-check-idps-private-ranges-before-interpreting-azure-firewall-traffic-direction/", "url": "https://update.dsesecurity.com/updates/dse-20260909-404-check-idps-private-ranges-before-interpreting-azure-firewall-traffic-direction/", "headline": "Check IDPS private ranges before interpreting Azure Firewall traffic direction", "description": "The IDPS private-range definition determines inbound, outbound and internal classification used by direction-specific signatures.", "abstract": "The IDPS private-range definition determines inbound, outbound and internal classification used by direction-specific signatures.", "articleBody": "Source facts\nAzure Firewall Premium IDPS uses configured private IP ranges to classify traffic as inbound, outbound or internal. Its signatures apply to specific directions. By default, only RFC 1918 ranges are classified as private, and traffic between private ranges is considered internal.\nAdministrators can edit, add or remove those ranges. The separate IDPS bypass list excludes selected addresses or subnets from filtering; Microsoft cautions that it is not intended as a throughput-improvement mechanism. Microsoft Learn.\nApplicability\nIdentify the relevant source and destination ranges and their intended network roles. Keep IDPS direction classification separate from routing, network-rule permission and a filtering bypass.\nDSE recommendation\nDSE recommends reviewing the address plan against the private-range definition before interpreting unexpected signature behavior. Have the network and security owners agree on the intended classification, including internally used space outside the default ranges. Correct an approved classification mismatch rather than immediately disabling a signature or bypassing an entire subnet.\nVerification\nUse authorized representative flows to compare their addresses and expected direction with the current IDPS configuration and signature scope. Preserve the pre-change definition and observed results. After an approved adjustment, retest both the intended path and an adjacent path that should retain its classification. Document unresolved differences without claiming that direction classification alone proves complete threat detection.\nOfficial references\nMicrosoft Learn: Azure Firewall Premium features implementation guide. Source retrieved September 9, 2026.", "datePublished": "2026-09-10T00:25:12+00:00", "dateModified": "2026-09-10T02:04:56+00:00", "mainEntityOfPage": { "@id": "https://update.dsesecurity.com/updates/dse-20260909-404-check-idps-private-ranges-before-interpreting-azure-firewall-traffic-direction/" }, "inLanguage": "en-US", "isAccessibleForFree": true, "author": { "@type": "Organization", "name": "DSE Security Editorial Team", "url": "https://update.dsesecurity.com/#editorial-team" }, "publisher": { "@id": "https://dsesecurity.com/#organization" }, "image": { "@type": "ImageObject", "@id": "https://update.dsesecurity.com/updates/dse-20260909-404-check-idps-private-ranges-before-interpreting-azure-firewall-traffic-direction/#primaryimage", "url": "https://update.dsesecurity.com/assets/editorial/network-infrastructure-social-v2.jpg?v=1.8.20", "contentUrl": "https://update.dsesecurity.com/assets/editorial/network-infrastructure-social-v2.jpg?v=1.8.20", "width": 1200, "height": 630, "caption": "Check IDPS private ranges before interpreting Azure Firewall traffic direction" }, "articleSection": [ "Cybersecurity", "Networks & Infrastructure" ], "keywords": [ "Cybersecurity", "Networks & Infrastructure", "Guide", "Information priority" ], "genre": "Guide", "about": [ { "@type": "Thing", "name": "Cybersecurity", "url": "https://update.dsesecurity.com/topic/cybersecurity/" }, { "@type": "Thing", "name": "Networks & Infrastructure", "url": "https://update.dsesecurity.com/topic/networks-infrastructure/" } ], "wordCount": 224, "timeRequired": "PT2M", "publishingPrinciples": "https://update.dsesecurity.com/updates/dse-updates-editorial-methodology/", "usageInfo": "https://update.dsesecurity.com/usage/", "copyrightHolder": { "@id": "https://dsesecurity.com/#organization" }, "copyrightNotice": "Copyright © 2026 Detection Systems & Engineering. All rights reserved.", "citation": { "@type": "CreativeWork", "name": "Azure Firewall Premium features implementation guide | Microsoft Learn", "url": "https://learn.microsoft.com/en-us/azure/firewall/premium-features" } } ] } }