# Azure Firewall > Guidance for Azure Firewall — managed cloud-native L3-L7 stateful network firewall for centralised egress, east-west, and ingress control. Covers SKU choice (Basic vs Standard vs Premium), Firewall Policy hierarchy, application/network/DNAT rules, threat intelligence and IDPS, TLS inspection, hub-spoke deployment with UDRs, and forced tunneling. WHEN: Azure Firewall, network firewall, egress filt… - **Type:** Skill - **Install:** `agentstack add skill-vinayaklatthe-microsoft-security-skills-azure-firewall` - **Verified:** Yes — security-reviewed for prompt injection and unsafe behavior - **Seller:** [vinayaklatthe](https://agentstack.voostack.com/s/vinayaklatthe) - **Installs:** 0 - **Category:** [Cloud & Infrastructure](https://agentstack.voostack.com/c/cloud-infrastructure) - **Latest version:** 0.1.0 - **License:** MIT - **Upstream author:** [vinayaklatthe](https://github.com/vinayaklatthe) - **Source:** https://github.com/vinayaklatthe/microsoft-security-skills/tree/main/skills/azure-firewall ## Install ```sh agentstack add skill-vinayaklatthe-microsoft-security-skills-azure-firewall ``` Requires the [AgentStack CLI](https://agentstack.voostack.com/docs/cli). Works with Claude Code, Cursor, and any MCP-compatible agent. ## About # Azure Firewall Azure Firewall is a managed, highly available, cloud-native stateful **network firewall** used to centrally govern and log traffic, typically deployed in the **hub** of a hub-spoke network. It is the choke point that enforces a default-deny egress posture across an Azure estate. ## When to use Centralising egress (and east-west / ingress) traffic control and inspection across an Azure network estate. Use this skill to pick the SKU, design rules, and deploy in the hub. **Do not use this skill** for L7 web app protection (WAF on Front Door / App Gateway), subnet microsegmentation (NSGs - see `azure-network-security-design`), or third-party NVA design. ## Pick the SKU by capability need | Requirement | SKU | Notes | |---|---|---| | SMB / dev / small estate, **Rule of thumb:** Standard SKU is right for most enterprise hubs in 2026. Move to Premium > only when you have a concrete TLS-inspection or IDPS requirement - the certificate / > PKI overhead of TLS inspection is real and breaks some apps. Basic only for SMB or sandbox. ## Approach 1. **Deploy in the hub** — Single firewall per region in the hub VNet (with at least two availability zones for resilience). All spokes peer to the hub; egress and east-west traffic flows through. *Verify: firewall has public IP for egress, deployed across ≥ 2 AZs, capacity baseline established.* 2. **Use Firewall Policy (not classic rules)** — Author rules in **Azure Firewall Policy** with **hierarchical** parent + child policies (e.g. parent = enterprise baseline, child = region-specific). Don't author rules per firewall. *Verify: policy hierarchy mapped; one base policy reused across regional firewalls.* 3. **Default-deny + structured rule collections** — Order: **DNAT** (inbound) → **Network rules** (IP/port/protocol) → **Application rules** (FQDN/URL). Inside each collection group, priority controls evaluation. Default action = deny. *Verify: a probe from a spoke to an unallowed FQDN is logged as deny.* 4. **Application rules with FQDN tags** — Use built-in **FQDN tags** (WindowsUpdate, AzureKubernetesService, Office365) for Microsoft service egress instead of hand-curated lists. Custom FQDNs for third-party SaaS. 5. **Force spoke egress through firewall via UDRs** — User-defined routes on spoke subnets: `0.0.0.0/0` next hop = firewall private IP. Without UDRs, traffic bypasses the firewall. *Verify: `Get-AzEffectiveRouteTable` on a spoke NIC shows next hop = firewall.* 6. **Enable threat intel + IDPS (Premium)** — Threat-intel-based filtering in **Deny** mode for known-bad IPs / FQDNs. Premium: enable **IDPS** in Alert+Deny for high-severity signatures; tune false positives. 7. **Stream logs and monitor capacity** — Send to Log Analytics / Sentinel using **structured firewall logs**. Use the workbook for top denied flows, capacity / throughput. *Verify: firewall workbook populated; alert on > 80% throughput sustained for 15 minutes.* ## Guardrails - **Azure Firewall complements, not replaces, NSGs (subnet/NIC microsegmentation) and WAF (L7 web).** Layered defence; each does a different job. - **TLS inspection (Premium) requires certificate / PKI planning.** Internal CA cert chain trusted on clients; some apps (cert-pinning, mTLS) break under inspection. Pilot first. - **Plan capacity and availability zones for resilient hub deployments.** Single-zone = single zone outage takes the hub down. - **UDRs are the enforcement.** Without `0.0.0.0/0 → firewall` on spokes, traffic doesn't go through. Audit UDRs as part of landing zone. - **Firewall Policy is hierarchical for a reason.** Don't author per-firewall rules at scale - they drift. - **Don't enable Premium features speculatively.** Cost is meaningfully higher; only enable when there's a use case. ## Common anti-patterns - **"Allow `*` for outbound to start"** - Defeats the firewall. Default-deny + named FQDN rules from day one. - **"Premium SKU for everyone"** - Cost without value if no IDPS / TLS inspection in scope. - **"TLS inspection on day one for all traffic"** - Breaks half the apps. Pilot per workload. - **"No UDR - we assume traffic goes through the firewall"** - It doesn't. Routes are the enforcement. - **"One single firewall, single zone"** - AZ outage = hub down. Multi-AZ from day one. - **"Don't log - it's noisy"** - First incident, no forensics. Structured logs + Sentinel always. ## Example prompts - `Design Azure Firewall egress filtering with FQDN and application rules in a hub-spoke topology.` - `When should I choose Firewall Premium with IDPS and TLS inspection?` - `Set up Firewall Policy hierarchy and force spoke egress through UDRs.` - `How do I protect Azure Virtual Desktop traffic with Azure Firewall?` - `Build a Sentinel workbook for top denied flows from Azure Firewall logs.` - `Plan capacity, availability zones, and DNS proxy for the hub firewall.` ## Microsoft Learn - Azure Firewall overview: https://learn.microsoft.com/azure/firewall/overview - Firewall Policy: https://learn.microsoft.com/azure/firewall/policy-rule-sets - Premium features (IDPS / TLS): https://learn.microsoft.com/azure/firewall/premium-features - Hub-spoke + firewall: https://learn.microsoft.com/azure/architecture/networking/architecture/hub-spoke - FQDN tags: https://learn.microsoft.com/azure/firewall/fqdn-tags - Threat intelligence: https://learn.microsoft.com/azure/firewall/threat-intel - Structured logs: https://learn.microsoft.com/azure/firewall/firewall-structured-logs - Forced tunneling: https://learn.microsoft.com/azure/firewall/forced-tunneling ## Source & license This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code. - **Author:** [vinayaklatthe](https://github.com/vinayaklatthe) - **Source:** [vinayaklatthe/microsoft-security-skills](https://github.com/vinayaklatthe/microsoft-security-skills) - **License:** MIT Install and usage instructions live in the source repository linked above. ## Pricing - **Free** — Free ## Security capabilities Automated source analysis of v0.1.0 — what this tool can access: - **Network access:** no - **Filesystem access:** no - **Shell / process execution:** no - **Environment & secrets:** no - **Dynamic code execution:** no *"Yes" means the capability is present in the source — more access means more to trust, not that it is unsafe.* ## Versions - **0.1.0** — security scan: passed — Imported from the upstream source. ## Links - Listing page: https://agentstack.voostack.com/l/skill-vinayaklatthe-microsoft-security-skills-azure-firewall - Seller: https://agentstack.voostack.com/s/vinayaklatthe - Browse the marketplace: https://agentstack.voostack.com/browse --- Listed on AgentStack — the marketplace for AI agent skills and MCP servers. Every listing is security-reviewed. Creators keep 70%.