Need to find Top talkers from Azure Firewall network Logs

Question

I want a KQL query and configuration settings which can give me Azure firewall network rule logs with column having details for SentBytes and received bytes details for each packet.

Answer 1

assuming you already configured Azure Firewall

sending logs to Log Analytics Workspace

the following may help to you

AzureDiagnostics
| where ResourceType == "AZUREFIREWALLS" and Category == "AzureFirewallNetworkRule"
| summarize TotalSentBytes = sum(SentBytes), TotalReceivedBytes = sum(ReceivedBytes) by SourceIP
| order by TotalSentBytes desc

Answer 2

To get Azure Firewall network rule logs with SentBytes and ReceivedBytes details for each packet, you can use the following KQL query in Azure Log Analytics:

AzureDiagnostics

| where ResourceType == "AZUREFIREWALLS" and Category == "AzureFirewallNetworkRule"

| project TimeGenerated, SourceIP, DestinationIP, Protocol, Action, SentBytes, ReceivedBytes

Answer 3

@Shramik Ghadigaonkar Thank you for reaching out.

In order to determine the top talkers in from Azure Firewall activating the top flow logs will be the way to go.

https://learn.microsoft.com/en-us/azure/firewall/monitor-firewall-reference#top-flows

The top flows log is known in the industry as fat flow log and in the preceding table as Azure Firewall Fat Flow Log. The top flows log shows the top connections that are contributing to the highest throughput through the firewall.

Make sure you have enabled structured firewall logs in this case

https://learn.microsoft.com/en-us/azure/firewall/monitor-firewall#enable-structured-logs

Enable the Top flows log using the following Azure PowerShell commands:

Set-AzContext -SubscriptionName <SubscriptionName>
$firewall = Get-AzFirewall -ResourceGroupName <ResourceGroupName> -Name <FirewallName>
$firewall.EnableFatFlowLogging = $true
Set-AzFirewall -AzureFirewall $firewall

Note: Activate Top flows logs only when troubleshooting a specific issue to avoid excessive CPU usage of Azure Firewall.

Please follow the documentation above for disabling the logs.

You can find the sample query here
https://learn.microsoft.com/en-us/azure/azure-monitor/reference/queries/azfwfatflow

// Get the fatflows from past 1000 samples with rate atleast 5 mbps
AZFWFatFlow
| take 1000
| order by TimeGenerated desc
| where FlowRate > 5

This is list of columns available for this log
https://learn.microsoft.com/en-us/azure/azure-monitor/reference/tables/azfwfatflow#columns

Currently this log does not contain the SentBytes and received bytes details and if top flow logs do not satisfy your requirements it will help if you could file a feedback item for this request along with your business requirement. You can file this request here

Hope this helps! Please let me know if you have any additional questions. Thank you!

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