Subject: Re: SSH File Transfer Protocol - draft-moonesamy-secsh-filexfer-00

From: Peter Gutmann <[email-masked]>
Date: Sun, 14 Jul 2013 02:57:26 +0000

Mouse <[email-masked]> writes:

>But, really, it provides a lot more than file transfer; it's really a remote
>filesystem access protocol, misnamed as a file transfer protocol.

I've always thought of it as an RPC mechanism for the Posix filesystem API.
I'm impressed at the level at which the Windows implementations manage to map
it to something that works under Windows.

What I'd like to see is two distinct profiles, one for "move a file from A to
B", a la SCP, which I suspect would satisfy 90% of users, and then the full
second-system-effect RPC-of-Posix-API mechanism for everyone else.  In
particular at the moment it's just way too hard to add basic remote-file-
transfer capabilities to your app without having to reimplement half the RPC
API.

In addition since there's no clear indication of which half you need, people
have to use trial-and-error.  I've talked to a few implementers of SFTP-like
functionality in apps and their target was to implement whatever was necessary
to get OpenSSH to send and receive a file, which seems like a pretty messy way
to do things.

For starters I'd use SCP/FTP functionality as a baseline, LS, GET/PUT/DELETE,
CHDIR/MKDIR/RMDIR/PWD, that's been enough for FTP for decades, it should be
good enough for standard SFTP functionality.

Peter.

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From: Damien Miller <[email-masked]>
Date: Mon, 22 Jul 2013 11:08:21 +1000 (EST)

> good enough for standard SFTP functionality.

Right, and that is basically what the -02 draft provides. Later versions
ran off a cliff trying to support every possible FS feature for every
possible OS, which is why OpenSSH never bothered with them.

-d