The “-sP” option in Nmap, which refers to (Network Mapper), is a highly useful tool for system and network administrators. Nmap is an open-source tool used by network professionals to scan networks, find open ports, and map network infrastructure.
In older versions of Nmap, the “-sP” option was utilized for something known as a “ping scan”. The “ping scan” is essentially a method used to discover hosts that are functioning and connected to the network, hence reachable. When given the “-sP” command, Nmap would send an ICMP echo request, commonly known as a “ping”, to each IP address in the specified range. If the host returned an ICMP echo reply, it was marked as up and reported in the results.
However, it’s essential to note that the “-sP” option has been replaced by the “-sn” option in Nmap’s recent versions. According to the official documentation of Nmap, “-sn” (No port scan) option is now used for host discovery which, essentially, performs the same function as “-sP”. This option tells Nmap not to do a port scan after host discovery, and only print out the available hosts that responded to the scan.
More on this, Nmap sends an ARP (Address Resolution Protocol) request to communicate with the target host inside the local network, and for hosts outside the local network, it uses ICMP echo request, TCP SYN to port 443, TCP ACK to port 80, and ICMP timestamp request to make the discovery.
Nmap with “-sn” option can be used for various types of network checks, for example, checking live hosts in the network, preparing for a penetration testing, ensuring strict network policies, or just to get a quick view of services running on the network.
Remember that using Nmap, especially techniques such as “-sP” or “-sn” scanning on any network without permission, is a violation of the Computer Fraud and Abuse Act in the United States and potentially equivalent laws in other countries. Always ensure you have the appropriate authorization before scanning a network.
To support this information, here are the sources used:
1. “Nmap Ping Scanning (-sP)” on Nmap Network Scanning (https://nmap.org/book/man-host-discovery.html)
2. “Official Nmap Documentation” by Gordon Lyon (https://nmap.org/book/man.html)
3. “Introduction to Network Scanning with Nmap” published on the University of Rhode Island’s Department of Electrical, Computer, and Biomedical Engineering website (http://www.ele.uri.edu/courses/csc3940/CSC3940_Spring_2011\_files/Nmap%20Tutorial.pdf).
4. “United States Computer Fraud and Abuse Act” (https://uscode.house.gov/view.xhtml?path=/prelim@title18/part1/chapter47&edition=prelim)
