I installed a vsftp server. It works, with command line 'ftp' I can connect to it and upload ('put') files. But if I type 'ls', then it hangs after displaying:
Entering Extended Passive Mode (|||<port>|)
Reading documentation and tutorials, I discovered that a lot of background regarding passive mode, extended passive mode and related port opening is expected from the maintainer of a vsftp server. All this is cryptic to me as I lack this background.
When using vsftp (and maybe ftp at large): what is passive mode, extended passive mode, why do they exist (i.e. to solve which issue) and how should they be be configured for the most common use cases?
