RFC 959, "File Transfer Protocol", October 1985

Note: This RFC has been updated by RFC 2228, RFC 2640, RFC 2773, RFC 3659, RFC 5797, RFC 7151

Errata ID: 7430
Status: Reported
Type: Technical
Publication Format(s) : TEXT
Reported By: Gordon Steemson
Date Reported: 2023-04-23

Section 5.2 says:

The direction of the transfer and the port used will be determined by the FTP service command.

It should say:

The direction of the transfer will be determined by the FTP service command.

Notes:

Per RFC 1123 (section "4.1.2.12 Connections"), the clause "and the port used" was a remnant of an earlier version of the standard, and ought to have been removed during the rewrite that produced RFC 959. Admittedly, RFC 1123 does only use the term "should" in saying to ignore the wording, as the behaviour described had been correct at one time -- but that time was meant to have ended 38 years ago. For the few brave souls who attempt to program FTP support in the modern day, this really ought to explicitly annotate the actual RFC.

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