FTP technical references
The IETF (Internet Engineering Task Force) is a large open international community of network designers, operators, vendors, and researchers that has been charged with developing and maintaining internet related protocols and implementations. The IETF releases RFC documents which serve as the definitive guide for FTP, HTTP, and many other protocols. The following documents are useful for understanding and implementing the FTP protocol.
RFC 959
This document provides fundamental details for the implementation of a file transfer protocol that is compatible between various computer systems.
RFC 2228
This document extends the security features of the FTP protocol. These extensions provide authentication and integrity on both the control and data channels. New new optional commands and replies are also defined.
RFC 2640
This document extends the FTP protocol for international audiences, and defines support for multiple character sets.
RFC 2577
This document provides suggestions for system administrators and those implementing FTP servers about potential security issues such as "bounce attacks".