In the first part of this series, we explored the critical role of network enumeration in cybersecurity, emphasizing its importance in understanding the devices and services on a network. One of the most powerful tools for this task is Nmap (Network Mapper), an open-source tool used for network discovery and security auditing. We started by highlighting the basics of Nmap, comparing it to an airport scanner that searches for hidden objects, except Nmap searches for open ports and services on computers. We then dived into host discovery, the initial step in network enumeration, where Nmap provides methods for identifying active devices on a network by scanning network ranges, lists of IP addresses, or multiple individual IPs.

The process included discovering live hosts without scanning ports using the -sn option and saving the results in various formats (-oA). We also explored how to filter and extract IP addresses from the output, and discussed the less common but useful method of scanning specific lists of IP addresses. Additionally, we covered the flexibility of Nmap in handling multiple IP addresses, emphasizing the importance of disabling ARP ping to ensure ICMP echo requests are used for ping scans.