Tries it’s best to establish a connection to a ftp-server. If cannot connect, retries tirelessly for network to come back up. If can connect, but cannot establish a DATA-connection, starts brute forcing with parallel ftp-connections to find an open port.
You should use ftp in passive mode for brute-forcing to work best.
git clone https://github.com/kivilahtio/Net-FTP-Brute && cd Net-FTP-Brute