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Re: FTP denial of service attack
From: mouse () RODENTS MONTREAL QC CA (der Mouse)
Date: Thu, 9 Dec 1999 00:06:37 -0500


As far as I can tell the ftp protocol has no way to name data
channels, so there's no way for *any* ftp client to use multiple
concurrent data channels without opening a separate control
connection for each one,

It makes sense that (if the ftp server supports is) for a second
file, for which I've made a second connection, to come down that
stream, etc.  The connections aren't named directly because there is
no need to.  The single order of operations within the FTP protocol
provides some assurance that file request A goes with connection a,
etc.

Now I'm *sure* I'm missing something.

Okay.  Send PASV or PORT.  Send STOR or RETR.  Bits start flowing over
the data connection.

Now, your control connection is, per the protocol, out of commission
until the transfer finishes - all you can do with it is SYNCH/IP and
ABOR.  How are you going to initiate a second transfer?  Even if you
had previously done another PASV/PORT?

Or are you proposing to revise the protocol in some way?  If so, at
least make it clear you're talking about a revised protocol, hmmm?

                                        der Mouse

                               mouse () rodents montreal qc ca
                     7D C8 61 52 5D E7 2D 39  4E F1 31 3E E8 B3 27 4B


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