Subject: Re: avoiding reinventing the wheel on file transfer.

From: Jeffrey Altman <[email-masked]>
Date: Wed, 28 Mar 2001 9:09:31 EST

I can agree with Bill's desire to not re-invent the wheel.  But I also
agree with Niels that the FTP solution is hardly clean and does not
really solve many of the issues it is attempting to address.

If you really want a protocol that is going to replace FTP (RFC 959
...) then you need to make it OS and file system independent.  It
needs to be able to provide a standardized wire format for:

 . file format (binary, ascii, record based, ...)

 . attributes (MacOS resources, OS/2 EAs, Unix permissions, owner,
   groups, time/date info, ACLs, ...)

 . directory structures (not everything uses slashes or is a single
   rooted tree)

 . character-set issues (for ascii files there needs to be a standard
   character-set.  at this point the choice is easy, something based 
   on Unicode.)

Not all of this information is useable by all OSs.  But when two
systems of the same type communicate you want files to be transfered
in their entirety.  When they move between systems, you want them to
be as close as possible.  These issues do not appear to be addressed
by the SSH group because there is no representation from non-Unix
communities.  Or because the SSH group believes that anything that is
non-Unix (or Win32) should no longer be used.

Before a decision can be made as to whether reusing FTP (RFC 959) or
building something else, you need to have a requirements document that
explains your needs.  Otherwise, you will never be happy with what is
produced.  

The Kermit project built the Internet Kermit Service (RFC 2839) in
order to create a secure, single channel solution which addresses the
requirements of transfering data among heterogeneous platforms.  I
strongly recommend that you look at the work that was done before
coming to any conclusion about how you should proceed.

 Jeffrey Altman * Sr.Software Designer      C-Kermit 7.1 Alpha available
 The Kermit Project @ Columbia University   includes Secure Telnet and FTP
 http://www.kermit-project.org/             using Kerberos, SRP, and 
 [email-masked]          OpenSSL.  SSH soon to follow.