Discovering hosts with UDP ping scans

Ping scans are used to determine if a host is responding and can be considered online. UDP ping scans have the advantage of being capable of detecting systems behind firewalls with strict TCP filtering but that left UDP exposed.

This next recipe describes how to perform a UDP ping scan with Nmap and its related options.

How to do it...

Open your terminal and enter the following command:

# nmap -sn -PU <target>  

Nmap will determine if the target is reachable using a UDP ping scan:

# nmap -sn -PU scanme.nmap.org 
   Nmap scan report for scanme.nmap.org (45.33.32.156) 
   Host is up (0.13s latency). 
   Other addresses for scanme.nmap.org (not scanned):     
   2600:3c01::f03c:91ff:fe18:bb2f 
   Nmap done: 1 IP address (1 host...