Unraid and Proxmox Charge Money to Run on Top of Open Source Software

William writes how do companies like Unraid and Proxmox get away with charging money. It's nothing stopping you from selling open source software as long as you provide the source code to it, he says. Red Hat take a bunch of open source software including the kernel and they effectively charge you to use it but the sources are available. Armul in X for example strip out all of the branding like the artwork, the names, the trademarks that sort of stuff and produce a binary compatible bug for bug as they call it clone of it.