Discovering hosts with ICMP ping scans
Ping scans are used to determine whether a host is online. ICMP echo request messages were designed specifically for this task, and naturally, ICMP ping scans use these packets to reliably detect the status of a host.
This 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
How it works...
The -sn -PE
options tell Nmap to send an ICMP echo request packet to the scanme.nmap.org
host. We can determine that a host is online if we receive an ICMP echo reply to this probe. Using the --packet...