Subfinder

Subfinder is a utility designed for identifying subdomains associated with a specified domain. It is commonly employed in cybersecurity tasks, particularly for penetration testing and security audits.

Subfinder works by sending requests to DNS servers and analyzing the responses. It can detect both known and unknown subdomains, which can be useful for:

Detecting hidden resources or services
Defining network boundaries and perimeter
Vulnerability testing and detection
Network security monitoring and control

Subfinder uses various sources to discover subdomains, including:

DNS resolvers
WHOIS databases
Internet archives
Open-source intelligence systems

As a result of its work, Subfinder can generate a report with information about the discovered subdomains, including their names, IP addresses, and other metadata.

Subfinder is a popular tool among information security specialists and penetration testers, as it allows for quick and effective subdomain discovery and information gathering.