[PLUG] FTP-response clarification

Ishak Micheil isaacem at gmail.com
Wed May 6 21:47:31 UTC 2015


I agree with the approach of blocking it. However we have some legacy
connections that we have to secure meanwhile decommissioning the operation
progress.



Thanks John for the RFC refrence.


Regards,

Ishak



On Wed, May 6, 2015 at 1:40 PM, John Meissen <john at meissen.org> wrote:

>
> isaacem at gmail.com said:
> > However the support team of our DLP software claiming that it is NOT
> standard
> > response and the "standard" response should follow this format
>
> > "220-Filezilla Server"
>
> > More specifically the "-" missing, causing our issue for not detecting
> FTP
> > response correctly.
>
> > Anyone with FTP guidance?
>
> RFC959 states:
>
>       A reply is defined to contain the 3-digit code, followed by Space
>       <SP>, followed by one line of text (where some maximum line length
>       has been specified), and terminated by the Telnet end-of-line
>       code.    There will be cases however, where the text is longer than
>       a single line.  In these cases the complete text must be bracketed
>       so the User-process knows when it may stop reading the reply (i.e.
>       stop processing input on the control connection) and go do other
>       things.  This requires a special format on the first line to
>       indicate that more than one line is coming, and another on the
>       last line to designate it as the last.  At least one of these must
>       contain the appropriate reply code to indicate the state of the
>       transaction.  To satisfy all factions, it was decided that both
>       the first and last line codes should be the same.
>
>          Thus the format for multi-line replies is that the first line
>          will begin with the exact required reply code, followed
>          immediately by a Hyphen, "-" (also known as Minus), followed by
>          text.  The last line will begin with the same code, followed
>          immediately by Space <SP>, optionally some text, and the Telnet
>          end-of-line code.
>
>             For example:
>                                 123-First line
>                                 Second line
>                                   234 A line beginning with numbers
>                                 123 The last line
>
>          The user-process then simply needs to search for the second
>          occurrence of the same reply code, followed by <SP> (Space), at
>          the beginning of a line, and ignore all intermediary lines.  If
>          an intermediary line begins with a 3-digit number, the Server
>          must pad the front  to avoid confusion.
>
> So to summarize, the "standard" response is a number followed by a space,
> unless the response is multi-line, in which case it's number followed by
> '-'
> (hyphen).
>
>
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