![]() ![]() To test DNS Server logging of audit events, we added an A record for and reloaded the zone. Once the Perl requirements for Windows have been met, restart the nxlog service via Windows Services.Read about the Windows requirements for Perl in the Perl (xm_perl) in the NXLog Reference Manual.Copy it to the location defined by the PerlCode directive in the xm_perl instance ( plxm, lines 1-4 above) and rename it to. Ensure that you have changed the values of WORKSPACE and SHAREDKEY to match those of your Log Analytics workspace.Use the output instance in this example nf configuration in your current C:\Program Files\nxlog\conf\nf NXLog configuration file.To prepare for testing, let’s run through the steps needed to ensure success: Since all REST API events are categorized by Azure Monitor as Custom Logs, Azure appends _CL to the value of Log-Type in order to prevent naming conflicts with other Azure tables thus the name we originally chose, DNS_Logs, appears in Azure Sentinel as DNS_Logs_CL.īy leveraging $SourceModuleName for defining Log-Type, we have created a completely generic output instance that can be used with any other log sources. Log-Type is dynamically set to $SourceModuleName, the name of the input instance we chose at the beginning. The values for the three HTTP headers Authorization, Log-Type, and x-ms-date are set using the add_http_header procedure as shown above on lines 41-43. Set_var('batch', get_var('batch') $delimiter $raw_event) $x_ms_date = strftime($parsedate_utc_false, '%a, %d %b %Y %T GMT') Īdd_http_header('Authorization',$authorization) Īdd_http_header('Log-Type',$SourceModuleName) $parsedate_utc_false = parsedate($dts_no_tz,FALSE) $dts = strftime(now(),'YYYY-MM-DDThh:mm:ssUTC') $ContentLength = string(size($raw_event)) If (size(get_var('batch')) size($raw_event) 3) > %SIZELIMIT% # The following can be used for debugging batch mode if needed: #-BEGIN- the enrichment of this event with any new fields: HTTPSCAFile %INSTALLDIR%\cert\ca-certificates.crt PerlCode %INSTALLDIR%\modules\extension\perl\ Configuring an NXLog agent to capture Windows DNS Server events using the Event Tracing for Windows (im_etw) input module is fairly straightforward as illustrated here: NXLog can natively collect ETW logs without the need to capture the trace into an. To allow easy integration with the NXLog HTTP(s) ( om_http) module that sends events to REST API endpoints, NXLog provides a Perl script that regenerates the single-use authorization string for each new batch of events to be sent. For details, see the Azure Monitor Authorization section in the Microsoft documentation. The value assigned to the Authorization header is dynamically generated using a cryptographic hash. Azure validates the values of two custom HTTP headers, Authorization and x-ms-date along with the length of the data payload to determine if the request is authentic. The pivotal part of sending secure HTTPS requests to Azure is the authentication process. For more information on supported platforms and how to install an agent, see the NXLog Deployment chapter of the NXLog EE User Guide.Ĭollecting DNS Server logs via Windows Event TracingĮvent Tracing for Windows (ETW) provides not only efficient logging of both kernel and user-mode applications but also access to the Debug and Analytical channels that are not available through Windows Event Log channels (which also contains some DNS Server logs). To evaluate the configurations presented in this post, download the appropriate trial edition for your platform. It offers many additional features not found in the free Community Edition. It can read and write all standard log formats and integrates with over 70 third-party products. If you aren’t familiar with the NXLog Enterprise Edition, it is a full-featured log processing agent with a small footprint. In comparison, Linux Audit has a much wider scope and could arguably be called the most comprehensive tool for monitoring and reporting security events on Linux distributions. Proactive monitoring of DNS activity can help network administrators quickly detect and respond to attempted security breaches in DNS implementations that might otherwise lead to data theft, denial-of-service, or other service disruptions related to malicious activity. Both of these log sources are of interest from a security perspective. We will present two examples of sending logs to Azure Sentinel: in the first one, we send Windows DNS Server logs and in the second one, Linux kernel audit logs. In this post, the technology we will be examining is the Azure Monitor HTTP Data Collector API, which enables clients, such as the NXLog Enterprise Edition agent, to send events to a Log Analytics workspace, making them directly accessible using Azure Sentinel queries. ![]()
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