Re: [ftpext] HOST back to FTPEXT2 WG for more review

[Robert McMurray <[e-mail]>]

In response to Daniel's and Paul's emails, which are archived at http://www.ietf.org/mail-archive/web/ftpext/current/msg00388.html and http://www.ietf.org/mail-archive/web/ftpext/current/msg00389.html respectively, Daniel brings up a point in section 3 that has been addressed before, which is where I documented two possible options when a HOST command is issued after the user has been authenticated.

After recent discussions, I do not think that this is necessary after all. In a separate thread it was suggested that the HOST draft should be specific and not provide both options, and after looking at Daniel's and Paul's emails I concede the point that it is probably better for the HOST draft to specify only one option. That being said, I agree with Paul that an implicit REIN is not the way to implement this. FTP already has a REIN command, and it's simple enough for a client to send a REIN command followed by HOST command if that's the desired behavior. Therefore the better option is to return a 503 reply for an erroneous sequence of commands when a HOST command is issued after the user has been authenticated. With that in mind, I am rewording that portion of section 3 as follows:

"Server-FTP processes that conform to this specification MUST treat a situation where the HOST command is issued more than once before the user has been authenticated as though a previous HOST command was not sent, and return the appropriate reply for the new HOST command. Server-FTP processes MUST treat a situation where the HOST command is issued after the user has been authenticated as an erroneous sequence of commands and return a 503 reply."

Of course, in situations where a server-FTP process does NOT implement the HOST command, the server-FTP process will return a 500 or 502 reply, as it would with any other unrecognized command.

As far as specifying a port is concerned, it does not make sense to pass a port in the HOST command. This concept has been discussed previously, see http://www.ietf.org/mail-archive/web/ftpext/current/msg00264.html for details.

Thanks!

--Robert