anasfanani/masscan-termux-android ? reverse-engineered prompt

Build me a fast command line TCP port scanner that works like nmap, but is lightweight and can run in Termux on Android too.

I want to be able to scan a host, a subnet, or a big IP range for one port or a list of ports, and have it print the open ports to the terminal or save them to a file. It should be able to run very quickly by sending SYN packets asynchronously, and it would be great if it can also grab simple banner info for common services like HTTP, SSH, SMTP, FTP, and similar when asked.

Make it build cleanly from source with a simple make command, and keep it usable on Linux and other platforms if possible. If there are any special caveats about raw packets, source IPs, or source ports, include clear warnings and sensible defaults. If you need to check the latest docs or build steps, look them up online.