If I had the powers, I would make it unlawful to use FTP. One of the troublesome protocols. Let alone it’s text based, the semantics are totally screwed. Active and passive mode. Yeah, that totally solves all the problems, right. Especially the 2 sockets (network connections) for file transfer. Is it intentionally so f*cked up to make firewall software much harder to get right? In short, it’s broken. Don’t use it. Let it die slowly.

Use SFTP wherever you can. If you are a system administrator, make the world a favour: never enable FTP on your servers.