aboul3la/Sublist3r ? reverse-engineered prompt

Build me a command-line tool in Python for finding subdomains. It's for people doing security testing or bug hunting. I should be able to give it a domain, like example.com, and it should use a bunch of public sources to find all the subdomains it can. It should check search engines like Google and Bing, but also specialized services like VirusTotal and Netcraft.

I also want it to have a bruteforce mode that uses a wordlist to guess common subdomain names like 'api', 'dev', and 'mail' to find ones that are not publicly listed. It should have options to enable this bruteforce mode, specify the target domain, and save the list of found subdomains to a text file. It would also be great to add an option to scan the found subdomains for specific open ports, like 80 and 443. Make it all work as a single Python script with a requirements.txt file.