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Description

Consider migrating from network security group flow logs to virtual network flow logs.

Retirement Notice On September 30, 2027, network security group (NSG) flow logs will be retired. Starting June 30, 2025, it will no longer be possible to create new NSG flow logs. Azure recommends migrating to virtual network flow logs. Review https://azure.microsoft.com/en-gb/updates?id=Azure-NSG-flow-logs-Retirement for more information. For virtual network flow logs, consider applying the policy Azure Virtual Network Flow Logs retention period is less than 90 days in this section.

Rationale​

Flow logs enable capturing information about IP traffic flowing in and out of network security groups. Logs can be used to check for anomalies and give insight into suspected breaches.

Impact​

This will keep IP traffic logs for longer than 90 days. First determine your need to retain data, then apply your selection here. As this is data stored for longer, your monthly storage costs will increase depending on your data use.

Audit​

This policy marks an Azure Network Security Group as INCOMPLIANT if any of the following conditions are met:

  • Flow Logs Retention Policy Enabled is set to false.
  • Flow Logs Retention Policy Days is configured to fewer than 90 days.

References​

  1. https://docs.microsoft.com/en-us/azure/network-watcher/network-watcher-nsg-flow-logging-overview
  2. https://docs.microsoft.com/en-us/cli/azure/network/watcher/flow-log?view=azure-cli-latest
  3. https://learn.microsoft.com/en-us/security/benchmark/azure/mcsb-logging-threat-detection#lt-6-configure-log-storage-retention