From: Reese Chappuis <c0dege3k@...>
Date: 2011-09-20T05:49:16+09:00
Subject: Re: FTP ports

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Thank you! That worked- and sorry Sam- the link you gave me just showed me
to the net/ftp page, and I didn't see anything about passive in there

On Sun, Sep 18, 2011 at 9:56 PM, Gary Wright <gwtmp01@mac.com> wrote:

>
> On Sep 18, 2011, at 9:18 PM, Reese Chappuis wrote:
>
> > The connect method suggestion didn't work. And I just noticed another
> thing-
> > the port number in the error keeps changing. In one test it was 11742,
> and
> > in the next it was 11728.
>
> ftp is an old protocol and has a somewhat unique architecture.
>
> The command connection is initiated by the client towards port 21.  When an
> actual
> file transfer is needed, the *client* begins listening on a local port that
> is
> picked by the OS (sometimes called an ephemeral port).  The client then
> tells the
> server which port number was allocated via the control connection (11742
> then
> 11728 in your instance).
>
> At this point the *server* initiates a data connection to
> the client towards the port number that was allocated by the client system.
>  This
> is called 'active mode' in the protocol spec.  This is where problems
> usually
> occur because many firewalls or administrative policies block that incoming
> TCP connection from the server to the client.
>
> An alternative is to tell ftp to use 'passive mode'.  In this mode, the
> *server*
> picks an ephemeral port, tells the client what it picked via the command
> connection, and then the client establishes the data connection towards the
> server.  In this mode the two TCP connections are both outbound from the
> client
> and can often negotiate any firewalls as necessary.
>
> You may be experiencing problems with either of these modes based on the
> firewall policies between the client and the server.
>
> You can set passive mode on as follows (based on quick look at net/ftp):
>
>        ftp = Net::FTP.new(hostname)
>         ftp.passive = true              # make sure you do this, defaults
> to false
>         ftp.login uname, pass
>        ftp.puttextfile filename, rfilename
>        ftp.close
>
>
> Gary Wright
>



-- 
Reese Chappuis

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