Connect Common Event Format Logs to Azure Sentinel

By Ashwin Venugopal -

 



Plan for Common Event Format Connector

Events from Linux-based Syslog-supporting machines or appliances can be streamed into Azure Sentinel using the Log Analytics agent which can be done for any device that allows you to install the Log Analytics agent directly on the host.

Log Analytics readily help in collecting the messages sent by the rsyslog or syslog-ng daemons, where rsyslog is the default that on version 5 of Red Hat Enterprise Linux (RHEL), CentOS, and Oracle Linux version sysklog is not supported for Syslog event collection. Sysklog should be replaced by rsyslog daemon for these versions of Linux.  

How it works?

Syslog is an event logging protocol that is common to Linux and when the Log Analytics agent for Linux is installed on your VM or appliance, the installation routine can easily configure the local Syslog daemon to forward messages to the agent on TCP port 25224 which in turn send the message to your Log Analytics workspace over HTTPS, where can be parsed into an event log entry in the Syslog table in Azure Sentinel logs.

Connect your External Solution using the CEF Connector    

Designation and configuration of a Linux machine should be done to forward the logs from your security solution to your Azure Sentinel workspace and by using the link provided, you can  thoroughly run a script on the designated machine that performs the following tasks:

Installs the Log Analytics agent for Linux and configures it for the following purposes:

  • Listening for CEF messages from the built-in Linux Syslog daemon on TCP port 25226
  • Sending the messages securely over TLS to your Azure Sentinel workspace, where they are parsed and enriched                                                                                                                                                                                                                                                      

Configures the built-in Linux Syslog daemon for the following purposes:

  • Listening for Syslog messages from your security solutions on TCP port 514
  • Forwarding only the messages it identifies as CEF to the Log Analytics agent on localhost using TCP port 25226 

Run the deployment script

To view the connector page:

  1. Select Data Connectors page.
  2. Select CEF
  3. Select the Open Connector page on the preview pane
  4. Verify that you have the appropriate permissions
  5. Copy the "sudo wget ..." and run with elevated permissions on the dedicated Linux VM 

Using the same machine to forward both plain Syslog and Common Event Format messages

If it is necessary to log forwarder machine to forward Syslog messages as CEF, to avoid the duplication of events to the Syslog and CommonSecurityLog tables:

On each source machine that sends logs to the forwarder in CEF format, and Syslog configuration file must be edited to remove the facilities used to send CEF messages.




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