Edit

Azure Firewall diagnostic logs (legacy)

  • Article

Diagnostic logs are the original Azure Firewall log queries that output log data in an unstructured or free-form text format.

The following log categories are supported in Diagnostic logs:

  • Azure Firewall application rule
  • Azure Firewall network rule
  • Azure Firewall DNS proxy

Application rule log

The Application rule log is saved to a storage account, streamed to Event hubs and/or sent to Azure Monitor logs only if you've enabled it for each Azure Firewall. Each new connection that matches one of your configured application rules results in a log for the accepted/denied connection. The data is logged in JSON format, as shown in the following examples:

Category: application rule logs.
Time: log timestamp.
Properties: currently contains the full message.
note: this field will be parsed to specific fields in the future, while maintaining backward compatibility with the existing properties field.

{
 "category": "AzureFirewallApplicationRule",
 "time": "2018-04-16T23:45:04.8295030Z",
 "resourceId": "/SUBSCRIPTIONS/{subscriptionId}/RESOURCEGROUPS/{resourceGroupName}/PROVIDERS/MICROSOFT.NETWORK/AZUREFIREWALLS/{resourceName}",
 "operationName": "AzureFirewallApplicationRuleLog",
 "properties": {
     "msg": "HTTPS request from 10.1.0.5:55640 to mydestination.com:443. Action: Allow. Rule Collection: collection1000. Rule: rule1002"
 }
}

{
  "category": "AzureFirewallApplicationRule",
  "time": "2018-04-16T23:45:04.8295030Z",
  "resourceId": "/SUBSCRIPTIONS/{subscriptionId}/RESOURCEGROUPS/{resourceGroupName}/PROVIDERS/MICROSOFT.NETWORK/AZUREFIREWALLS/{resourceName}",
  "operationName": "AzureFirewallApplicationRuleLog",
  "properties": {
      "msg": "HTTPS request from 10.11.2.4:53344 to www.bing.com:443. Action: Allow. Rule Collection: ExampleRuleCollection. Rule: ExampleRule. Web Category: SearchEnginesAndPortals"
  }
}

Network rule log

The Network rule log is saved to a storage account, streamed to Event hubs and/or sent to Azure Monitor logs only if you've enabled it for each Azure Firewall. Each new connection that matches one of your configured network rules results in a log for the accepted/denied connection. The data is logged in JSON format, as shown in the following example:

Category: network rule logs.
Time: log timestamp.
Properties: currently contains the full message.
note: this field will be parsed to specific fields in the future, while maintaining backward compatibility with the existing properties field.

{
 "category": "AzureFirewallNetworkRule",
 "time": "2018-06-14T23:44:11.0590400Z",
 "resourceId": "/SUBSCRIPTIONS/{subscriptionId}/RESOURCEGROUPS/{resourceGroupName}/PROVIDERS/MICROSOFT.NETWORK/AZUREFIREWALLS/{resourceName}",
 "operationName": "AzureFirewallNetworkRuleLog",
 "properties": {
     "msg": "TCP request from 111.35.136.173:12518 to 13.78.143.217:2323. Action: Deny"
 }
}

DNS proxy log

The DNS proxy log is saved to a storage account, streamed to Event hubs, and/or sent to Azure Monitor logs only if you’ve enabled it for each Azure Firewall. This log tracks DNS messages to a DNS server configured using DNS proxy. The data is logged in JSON format, as shown in the following examples:

Category: DNS proxy logs.
Time: log timestamp.
Properties: currently contains the full message.
note: this field will be parsed to specific fields in the future, while maintaining backward compatibility with the existing properties field.

Success:

{
  "category": "AzureFirewallDnsProxy",
  "time": "2020-09-02T19:12:33.751Z",
  "resourceId": "/SUBSCRIPTIONS/{subscriptionId}/RESOURCEGROUPS/{resourceGroupName}/PROVIDERS/MICROSOFT.NETWORK/AZUREFIREWALLS/{resourceName}",
  "operationName": "AzureFirewallDnsProxyLog",
  "properties": {
      "msg": "DNS Request: 11.5.0.7:48197 – 15676 AAA IN md-l1l1pg5lcmkq.blob.core.windows.net. udp 55 false 512 NOERROR - 0 2.000301956s"
  }
}

Failed:

{
  "category": "AzureFirewallDnsProxy",
  "time": "2020-09-02T19:12:33.751Z",
  "resourceId": "/SUBSCRIPTIONS/{subscriptionId}/RESOURCEGROUPS/{resourceGroupName}/PROVIDERS/MICROSOFT.NETWORK/AZUREFIREWALLS/{resourceName}",
  "operationName": "AzureFirewallDnsProxyLog",
  "properties": {
      "msg": " Error: 2 time.windows.com.reddog.microsoft.com. A: read udp 10.0.1.5:49126->168.63.129.160:53: i/o timeout”
  }
}

msg format:

[client’s IP address]:[client’s port] – [query ID] [type of the request] [class of the request] [name of the request] [protocol used] [request size in bytes] [EDNS0 DO (DNSSEC OK) bit set in the query] [EDNS0 buffer size advertised in the query] [response CODE] [response flags] [response size] [response duration]

Storage

You have three options for storing your logs:

  • Storage account: Storage accounts are best used for logs when logs are stored for a longer duration and reviewed when needed.
  • Event hubs: Event hubs are a great option for integrating with other security information and event management (SEIM) tools to get alerts on your resources.
  • Azure Monitor logs: Azure Monitor logs is best used for general real-time monitoring of your application or looking at trends.

Enable diagnostic logs

To learn how to enable the diagnostic logging using the Azure portal, see Monitor Azure Firewall logs (legacy) and metrics.

Next steps