Re: [Net::FTPServer] FTP<>SFTP bridge?

[Richard Jones]

On Thu, Dec 18, 2003 at 04:47:40PM -0800, Ken McGlothlen wrote:
> I've been trying to secure communications on my network, getting rid of old
> protocols and embracing encryption as much as possible.  One of those moves 
> was
> to finally retire my FTP server.
> 
> Unfortunately, there are still some clients out there that just can't manage
> secure communications, the most problematic of which (for me) is Adobe GoLive.
> It only supports HTTP and FTP.
> 
> Tunnelling FTP over SSH hasn't been very successful, either; I keep getting
> 
>       421 Service not available, remote server has closed connection.
> 
> errors with the following command sequence:
> 
>       $ ssh -L 8021:destination.host:21 destination.host  # in window 1
>         $ ftp -P 8021 localhost                             # in window 2

I think the reason this may not work is because FTP uses two
connections, one for the control connection (in this case on port
8021) and one other for each data connection.  Data connections happen
each time you type 'dir', or upload or download a file.

In addition, data connections may happen in either direction, this
being the difference between active and passive mode.  It's all rather
more complex than something which can be handled by an ssh tunnel.

> There's a Java application called Mindterm that ostensibly allows you to have 
> a
> local server that emulates an FTP server but actually talks to a remote SFTP
> server.  Unfortunately, it's not very good, and doesn't even seem to work on a
> Mac OS X system.

SFTP is a separate protocol, as far as I'm aware.  A server and client
are available for Mac OS X - it's called OpenSSH, and it should be
installed already on all recent versions.

> I've been poking around with Net::FTPServer and Net::SFTP, trying to create a
> Frankensteinian version of such an FTP<>SFTP bridge.  I've only just started,
> but Net::FTPServer is a big chunk of unfamiliar code, and I'm under some time
> pressure.
> 
> What I'm trying to find out is:
> 
>      *        Has anyone already done this in Perl?

Not as far as I know.

>      *        Has anyone already done this with Net::FTPServer somewhere?

I don't think so.

>      *        If not, is anyone familiar enough with the code that it seems 
> like an
>       easy addition, and if so, could I somehow talk you into it with, say,
>       some local microbrews?  (I live in Seattle.)

The problem is with the port numbers and data connections - see above.

>      *  If not, could someone more familiar with the code give me a pointer on
>       the best way to go about this?

Rich.

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