FTP

networking

Stands for: File Transfer Protocol

An old, unencrypted protocol for transferring files between hosts.

File Transfer Protocol (RFC 959) uses separate control and data connections and sends credentials in the clear, which is why it has largely been replaced by SFTP or FTPS for anything sensitive.

FTP separates control and data onto different connections, which is why it interacts badly with firewalls and NAT: the data connection's port is negotiated inside the control channel, so a stateless filter cannot know what to permit. Active mode has the server connect back to the client, which almost nothing allows any more; passive mode has the client connect out, which is why it became the default.

It also transmits credentials and data in clear text. FTPS adds TLS to the same protocol and keeps the dual-connection awkwardness; SFTP is unrelated, being a subsystem of SSH over one connection, and is the better answer for essentially every case. The persistence of plain FTP is almost entirely legacy integrations nobody has been funded to replace.

Also known as: ftp

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