Issues with count_hosts_by_os example

[mikemadden42]

I'm seeing a few issues with the count_hosts_by_os example in this repository.

I get this error when I run the program without sudo. Does this example require to be ran with sudo or root?

$ ./count_hosts_by_os
2021/05/23 07:03:44 nmap scan failed: unable to parse nmap output, see warnings for details

When I run the example, the number of Linux hosts is more than the number of hosts seen on the network.

$ sudo ./count_hosts_by_os
Discovered 25 linux hosts and 0 windows hosts out of 18 total up hosts.

[Ullaakut]

Hi @mikemadden42 ! Thanks for opening this issue :) It indeed requires root privileges, since in order to detect operating systems, nmap needs to do TCP/IP fingerprinting.

As for the inaccurate counts, I think I know what is happening, but just to be sure, could you please run the following on your machine?

sudo nmap -F -O 192.168.0.0/24

I think what happens is that the OS detection counts multiple times per host, in some cases. I am unable to reproduce it on my network though, which is why it would be helpful to see the output you are getting :)

Either way, the fix is as simple as adding a break statement when we increase the count for a host, to avoid counting more than once per host.

[mikemadden42]

Hi @Ullaakut , is there a subset of information I could provide? The full output of the nmap command you listed above could expose a lot of internal information.

[Ullaakut]

Hi @mikemadden42,

Sure, you could just manually check whether or not it shows multiple OSes per host, and let us know here :)