An Nmap scan shows the following open ports, and nmap also reports that the OS guessing results to match too many signatures hence it cannot reliably be identified:
21 ftp
23 telnet
80 http
443 https
What does this suggest ?
A.
This is a Windows Domain Controller
B.
The host is not firewalled
C.
The host is not a Linux or Solaris system
D.
The host is not properly patched
Explanation:
If the answer was A nmap would guess it, it holds the MS signature database, the host not being firewalled makes no difference. The host is not linux or solaris, well it very well could be. The host is not properly patched? That is the closest; nmaps OS detection architecture is based solely off the TCP ISN issued by the operating systems TCP/IP stack, if the stack is modified to show output from randomized ISN’s or if your using a program to change the ISN then OS detection will fail. If the TCP/IP IP ID’s are modified then os detection could also fail, because the machine would most likely come back as being down.