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Active and passive mode sound like personality types, but they simply decide who starts the data connection. In active mode, your computer tells the server which port it is listening on, and the server calls you back. That is like asking a stranger to ring your mobile while you are standing behind a firewall. Your…
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Port 21 walks into a bar and orders a drink. Then it asks a second port to carry the drinks to the table. That, in short, is how FTP works. FTP uses two connections. The control channel on port 21 carries commands such as USER, PASS and STOR. The data channel carries the actual files,…
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File Transfer Protocol was born in 1971, which makes it roughly as old as the floppy disk. Its job is simple: move files from one computer to another. It has done that job faithfully for decades. The trouble is that FTP was designed in a friendlier era, when the internet was a handful of universities…