RFC 491 (rfc491) - Page 2 of 2
What is "Free"?
Alternative Format: Original Text Document
RFC 491 What Is Free 12 April 1973 command would be right. (Presumably, FROM would be followed by PASS.) Being reasonably familiar with one of the systems which does allow access control on mailboxes, let me point out how it works: permissible "principal identifiers" are placed on the "access control list" of the mailbox, and when the mailbox is referenced by a process the principal identifier of that process must match (explicitly or as a member of a class) an entry on the list or access will be forbidden. But the principal identifier is associated with the process at login. Now, it is probably a valid objection to say that accounting should be separated from authentification, but it isn't always. So why invent a redundant mechanism based on the assumption that it is? Another point on authentication via login: it has been argued that FTP mail ought to be so cheap that it "can be buried in overhead" by the same token, if it's so cheap it shouldn't bother anybody to login on his own account if he wants to prove the mail's from himself. To be scrupulous, I should close by mentioning the possibility that NETML might be repugnant to some Hosts. If such be the case, then I propose that a new FTP FREE command be introduced so that Servers need not recognize MAIL as an implicit login. The reasons here are at least twofold: First, it appears that when the "subcommands" to MAIL get worked out, some of them will have to precede the MAIL (or users will set awfully tired of typing their names, etc.); therefore, the list of commands which imply a login grow and grow and Server FTP's will have to change and change. Second, if MAIL implies a login, it will be hard in some environments to get the arguments across to the process created on behalf of the mailer (and it is not a good idea at all to assume that the mailing can be handled by the process which is listening on socket 3). Even introducing a new mechanism (and see RFC 451 for my strong feelings against that sort of step in general) in FREE seems better than making all the assumptions that the loginless alternative does. Note that an alternative to this whole line of reasoning would be simply to observe that the FTP is internally inconsistent in that it acknowledges on the one hand (in the definition of the USER command) that some systems may require USER / PASS and then (mis)states on the other hand (in the discussion of mail) that they may not. If this abstract point is more satisfying to some readers than the foregoing pragmatic argument, well and good. [This RFC was put into machine readable form for entry] [into the online RFC archives by Helene Morin, Via Genie,12/1999] Padlipsky
