[e2e] overlay over TCP

[Mark Allman]

> The way the PORT command is spec'd, it almost looks like you could
> initiate a transfer remotely from a separate machine (A tells B to
> send a file to C) too. (anyone know whether that's possible? ever
> implemented?)

Yep.  That was a "feature".  And, it has been implemented in at least
the BSD FTP clients/servers.  Some claim that this is a security problem
and so the feature might be disabled by this point.

As a side note, the ftpext WG extended PORT and PASV to do IPv6 a while
back.  We proposed something that allowed for choosing the network
protocol, as well as the transport protocol.  The WG felt that
negotiating the transport protocol was unnecessary because we {were
stuck with / didn't need more than} TCP.  So, that part was ripped out.
The resulting RFC is:

    Mark Allman, Shawn Ostermann, Craig Metz. FTP Extensions for IPv6
    and NATs, September 1998. RFC 2428.

And, a companion tech report on what the proposal looked like before we
chopped it to match WG consensus:

    Mark Allman, Shawn Ostermann. FTP Extensions for Variable Protocol
    Specification. Technical Report CR-209414, NASA Glenn Research
    Center, February 2000.
    http://www.icir.org/mallman/papers/ftp-var-spec.ps

allman


--
Mark Allman -- ICIR -- http://www.icir.org/mallman/



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