Provide secure RDP/SSH access to Azure VMs without exposing management ports to the internet.
→Deploy Azure Bastion (Standard SKU for advanced features).
Why: Bastion acts as a managed jump box, providing access via the Azure portal over TLS. It eliminates the need for public IPs on VMs for management.
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Access an Azure PaaS service (e.g., SQL, Storage) using a private IP address from within your VNet.
→Create a Private Endpoint for the PaaS resource. Integrate with a Private DNS Zone for automatic name resolution.
Why: Private Endpoint projects the PaaS service into your VNet with a private IP, enabling truly private connectivity. Disabling public network access on the PaaS service enforces this.
Access Azure PaaS services from a VNet over the Azure backbone without using public IPs, but without managing a dedicated private IP.
→Enable a Service Endpoint for the specific service (e.g., Microsoft.Storage) on the source subnet.
Why: Service Endpoints provide a direct route to PaaS services from a VNet, but don't use a private IP in the VNet. It is simpler but less flexible than Private Endpoints.
Expose a service running in your VNet to consumers in other VNets (potentially other tenants) privately.
→Place the service behind a Standard Load Balancer and create a Private Link Service pointing to it.
Why: Private Link Service is the provider-side component. Consumers create Private Endpoints in their VNets to connect to your service privately.
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Simplify NSG rules for a multi-tier application where VMs may scale or change IPs.
→Create Application Security Groups (ASGs) for each tier (e.g., Web, App, DB). Define NSG rules using ASGs as source/destination.
Why: ASGs act as network object tags for VMs, allowing you to create rules based on application structure rather than brittle IP addresses.
Traffic is unexpectedly blocked when NSGs are applied to both a NIC and its subnet.
→Recall the NSG rule evaluation order. Inbound: NIC rules first, then Subnet rules. Outbound: Subnet rules first, then NIC rules.
Why: A deny at any level will block the traffic. Both NSGs must permit the traffic flow for it to succeed.
Automatically block traffic to/from known malicious IP addresses and domains.
→Enable Azure Firewall Threat intelligence-based filtering in "Alert and deny" mode.
Why: This uses Microsoft's threat intelligence feed to provide managed, up-to-date protection against known threats with zero configuration.
Inspect encrypted HTTPS traffic for threats like malware.
→Use Azure Firewall Premium. Enable TLS Inspection in the policy and deploy an intermediate CA certificate that clients must trust.
Why: This is a premium feature that performs a man-in-the-middle decryption to inspect traffic, which is critical for a zero-trust security posture.
Allow outbound access to complex Microsoft services like Windows Update without maintaining IP lists.
→In Azure Firewall, create an Application Rule using FQDN Tags (e.g., "WindowsUpdate", "AzureBackup").
Why: Microsoft manages the FQDNs associated with these tags, simplifying firewall rule management for dynamic services.
Protect public-facing applications from volumetric DDoS attacks and get access to rapid response support.
→Enable DDoS Network Protection (formerly Standard) on the VNet.
Why: Provides adaptive tuning, attack telemetry, mitigation reports, and access to the DDoS Rapid Response team, which the free Basic protection lacks.
Diagnose a connectivity failure and identify the exact hop where traffic is being dropped.
→Use Network Watcher > Connection Troubleshoot.
Why: It performs an end-to-end check, showing the full hop-by-hop path and pinpointing failures due to NSGs, UDRs, or other network issues.
Quickly verify if an NSG rule is allowing or denying traffic to/from a VM.
→Use Network Watcher > IP Flow Verify.
Why: This is the most direct tool to test a specific 5-tuple against NSG rules and see which rule is responsible for the outcome.
Log all allowed and denied network traffic for compliance and analysis.
→Enable NSG Flow Logs and ingest them into Traffic Analytics (via a Log Analytics Workspace).
Why: NSG Flow Logs provide raw traffic data. Traffic Analytics enriches and visualizes this data to identify traffic patterns, top talkers, and security threats.