Re: A future for the SSH File Transfer Protocol?

[Markus Friedl <markus%openbsd.org@localhost>]

On Sat, Nov 10, 2001 at 01:45:41PM -0500, RJ Atkinson wrote:
> At 13:42 10/11/01, Markus Friedl wrote:
> >i don't understand the problem with SFTP.
> 
> Might not be a problem, but folks want to understand 
> the problem SFTP is trying to solve.
> 
> For example, I'm trying to puzzle out how SFTP
> is different from SCP and why I would care about
> that difference (if I knew what it was)...

the RCP/SCP protocol has many drawbacks so SFTP acts as a simple
replacement for SCP. recent problems include:

error handling in RCP is broken: you send the filesize and the
filecontent to the remote host, if there is an readerror during the
transfer, you cannot stop the transfer for this file, because the two
scp processes might get out of sync.

RCP uses \n in the protocol, so you cannot transfer a filename
containing newlines.

if the remote host is the source of the transfer, the remote host tells
the local scp process the filesnames that should be created (e.g.  more
or different files than requested). with SFTP the local process sends
opendir/readdir/read messages and decides what files to copy.

and so on. i don't think it's worth using RCP/SCP as a starting point.

-m