The operating system for a host was identified incorrectly. For example, a host running Windows is reported as running Linux. What should I do?
This can typcally happen when mapping or scanning a host through a firewall. The scanner engine uses TCP fingerprinting to identify the operating system. As a result, the operating system for the hosts is reported as the operating system of the firewall instead because the response from the host has to be translated through the firewall.
Mapping through firewalls can cause incorrect and incomplete results. The best way to map those hosts is to have a scanner appliance on the same network as the target hosts, allowing you to map them without going through the firewall.
If the issue is not related to the firewall, please contact Qualys Support and they will work with you to properly fingerprint and identify the operating system in question.
Qualys Support KnowledgeBase