Re: Passive sftp?

FTP has become complicated. These are two standards for secure ftp
SFTP and FTPS.

SFTP operates like ssh/scp. It uses the same port (port 22). openssh
supports sftp both client and server.

FTPS operates like ftp and ssl/tls (port 20/21, etc). Among the ftp
clients that now support this addition are gftp and fireftp. vsftpd is
a FTPS server.

On Wed, Mar 5, 2008 at 9:29 PM, Tom Lobato <tomlobato@xxxxxxxxx> wrote:
Bob Rasmussen escreveu:

> In the FTP protocol, "passive" means that only one connection is
> established, originating in the client. All trafic goes over this
> connection. (In non-passive FTP, the server opens a second channel back to
> the client.)
>
> No such differentiation exists in SFTP. There is only one connection.
>
> The vendor may be using "passive" in a different sense, but I don't think
> it is a widely accepted usage.

in really, both passive and active ftp modes uses two connections. The
first, which is originated on client (to port 21 on server), is the
control connection, for authentication, command/response exchanges, etc.
The second connection, which transfer effective data, support two modes:
passive: originated from client to server. Uses destination port
defined on control connection.
active: originated from server to client. Uses destination port 20 on
client.

See http://www.faqs.org/rfcs/rfc1579.html (Firewall-Friendly FTP).

good resources:
http://en.wikipedia.org/wiki/File_Transfer_Protocol
http://www.slacksite.com/other/ftp.html
http://www.faqs.org/rfcs/rfc959.html (for the braves!)


Tom Lobato
www.tinecon.com.br


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