Substr3am
Passive reconnaissance/enumeration of interesting targets by watching for SSL certificates.
Substr3am is a python tool inspired by subbrute and Sublist3r designed to generate a list of potential subdomains using the certstream service. It helps penetration testers and bug hunters collect and gather subdomains for their lists by connecting to the certstream firehose, watching for real subdomains, and adding them to a list for use with the above tools.