In the era of rapid digital transformation, network security has become a critical concern for organizations and individuals alike. Vulnerabilities arising from open ports and misconfigured network services are among the most common entry points for cyberattacks. This research focuses on the design, development, and implementation of a custom port scanner and network mapping tool aimed at identifying open ports, active hosts, and service versions within a target network. Unlike generic commercial scanners, this custom tool provides flexibility, transparency, and adaptability for specific network environments. The study addresses key challenges such as scanning efficiency, accuracy of service detection, and reduction of false positives. The tool employs TCP connect scanning, SYN scanning, and banner grabbing techniques to map network topologies and detect potential security loopholes. Experimental results demonstrate that the proposed tool effectively identifies active ports, running services, and operating system fingerprints with high accuracy and minimal network overhead. The findings emphasize the importance of custom security tools in educational and small enterprise settings where cost and customization are significant factors. This research contributes to the field of network security by providing a lightweight, open-source alternative for port scanning and network enumeration, along with recommendations for integrating such tools into regular security auditing practices.