GVM no detection of OS


When i scan some servers i don’t get the OS while NMAP does perfectly. Why ?

Thank you for your answers.

Some wild guessing based on the minimal info provided:

  1. the portlist used in nmap differs from the one used in GVM (See https://docs.greenbone.net/GSM-Manual/gos-20.08/en/scanning.html#creating-port-lists for creating a port list in GVM)
  2. a detection of the OS is only covered by VTs included in the commercial GCF feed
  3. no detection for the mentioned OS exists (See Call for info: Unknown OS and Service Banner Reporting how to contribute)
  4. there are some other unknown factors (like a network equipment in between the scanner and the target, using outdated versions of GVM, …) causing a missing detection