Anssi Saari wrote:
John Nagle <na...@animats.com> writes:
In theory, the FTP spec supports "three-way transfers", where the
source, destination, and control can all be on different machines.
But no modern implementation supports that.
I remember even using that way back when, Unix machines in the 1990s.
But, server to server transfers are supported even today, since it's
part of the RFC. RFC959 explains how it's done in chapter 5.2. Usually
this is called FXP now.
http://en.wikipedia.org/wiki/Comparison_of_FTP_client_software lists a
bunch of clients with FXP support. I don't know about doing this with
ftplib, though.
Although the protocol allows setting up a 3-way transfer, many
FTP servers disallow data connections to an IP address different
from the control address. It's a security risk.
It's useful when you want to move data between machines with high
bandwidth connections, as within a server farm, and the control machine
has less bandwidth. But there are more modern approaches for that.
John Nagle
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