network – nmap -oG X.X.X.0-255 doesn’t work and all my ports closed ( expected list of open ports )


I’m running kali Linux on VirtualBox. I ran sudo ifconfig to get my IP and subnet mask (X.X.X.15 and 255.255.255.0 for eth0)

I tried the command nmap -oG X.X.X.0-255 -vv but I got

Read data files from: /usr/bin/../share/nmap
WARNING: No targets were specified, so 0 hosts scanned.
Nmap done: 0 IP addresses (0 hosts up) scanned in 0.07 seconds

When I remove the -oG option, I get a result of scanning 265 host and one is up which is

X.X.X.15 // my ip  

But all ports are closed. I don’t know why. Can you help me?

I’m following this tutorial.