Discovering hosts with ICMP ping scans

Ping scans are used to determine if a host is online. ICMP echo request messages were designed specifically for this task, and naturally, ping scans use these packets to reliably detect the status of a host.

The following recipe describes how to perform an ICMP ping scan with Nmap and the flags for the different types of supported ICMP messages.

How to do it...

To make an ICMP echo request, open your terminal and enter the following command:

# nmap -sn -PE <target>  

If the host responded, you should see something similar to this:

# nmap -sn -PE scanme.nmap.org 
   Nmap scan report for scanme.nmap.org (74.207.244.221)  
   Host is up (0.089s latency).  
   Nmap done: 1 IP address (1 host up) scanned in 13.25 seconds  

...