Fails to Process Requests Behind a NAT Firewall Due to DNS Resolution in Web Agent
Article ID: 76231
Updated On:
Products
Issue/Introduction
When running a Web Agent on IIS and a user sends a request to a specific protected resource, the browser does not receive the page, and the Web Agent reports the following error:
[04/03/2018][10:37:26][1896][5652][CSmHighLevelAgent.cpp:321][ProcessRequest][][][][][][][Start new request.][04/03/2018][10:37:26][1896][5652][CSmResourceManager.cpp:75][CSmResourceManager::ProcessResource][][][][][][][Calling SM_WAF_HTTP_PLUGIN->ProcessResource.][04/03/2018][10:37:26][1896][5652][CSmResourceManager.cpp:94][CSmResourceManager::ProcessResource][][][][][][][SM_WAF_HTTP_PLUGIN->ProcessResource returned SmExit.][04/03/2018][10:37:26][1896][5652][CSmResourceManager.cpp:160][CSmResourceManager::ProcessResource][][][][][][][Plugins did not collect required resource data.][04/03/2018][10:37:26][1896][5652][CSmHighLevelAgent.cpp:348][ProcessRequest][][][][][][][ResourceManager returned SmExit, end new request.][04/03/2018][10:37:26][1896][2196][CSmHighLevelAgent.cpp:321][ProcessRequest][][][][][][][Start new request.][04/03/2018][10:37:26][1896][5652][CSmLowLevelAgent.cpp:3567][ReportHealthData][][][][][][][Accumulating HealthMonitorCtxt.]
The Web Agent has a firewall in front of it that performs NAT (Network Address Translation).
Environment
Web Agent 12.52SP1CR11
Resolution
In the Web Agent ACO, set DisableDNSLookup to yes.
This parameter disables DNS lookup for all requests. This is safe to do, as it also helps prevent DNS Denial of Service (DoS) attacks, as described in the documentation (1).
Ensure the parameter syntax is correct, per the documentation link below (1)(2)(3)(4).
Additional Information
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