Re: FTP passive mode again

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Date: 20 Jul 2004 16:23:00 -0700

ibuprofin@painkiller.example.com (Moe Trin) wrote in message news:<slrncfokob.qdn.ibuprofin@atlantis.phx.az.us>...
> In article <9efa6216.0407181201.3d4365e3@posting.google.com>, JRoot wrote:
> >After reading the faq's and several of the posted messages on this
> >forum, I'm still getting nowhere, other than a headache, with trying
> >to ftp.
>
> Well, there's also the man page, and a nearly useless built-in help.
>
> >After a successful logon, the session proudly announces it is in
> >Passive mode
>
> Did you give the 'passiv' command? It takes two to Tango.
>
> >and then just hangs while it goes down the rabbit hole with Alice and
> >the Mad Hatter leaving me with no choice other than to kill the
> >session. Bummer.
>
> There are two modes - active and passive - but commands should be
> accepted (and acknowledged) is either mode. If you are active and the
> peer is passive (or vice-versa), then you won't see the results of
> the commands, and probably won't get another prompt.
>
> >I know this passive stuff is some sort of handshaking between the
> >client and server
>
> No. In Active mode, you send a command from some high port number
> (for example, 1050) to the server's port 21. The response comes back
> from his port 21 to your 1050. You then give a command, like 'dir'
> which goes out on your 1050, to his 21. The command acknowledgement
> comes back from his 21 to your 1050, and ftp then opens ANOTHER
> connection from (for example) 1052 to his port 20, and the data
> (in this example a list of files) comes back from his port 20 to your
> 1052. The difference between active and passive mode is that in
> passive, the _second_ data connection is not created, and the data
> comes to you on his 21 to your 1050. This makes more work for the
> client, but only uses one network connection. The problem occurs
> when one is active and the other passive, because one is sending data
> on a different port, while the other is listening on the same port (or
> vice versa). This situation _looks_ as if the service is wedged, but
> one is waiting for the other to respond.
>
> >so do I have to talk to my ISP and have them configure something at
> >their end
>
> Nope
>
> >or is there something I can do?
>
> _AFTER_ you log in to the ftp server, but before issuing any commands
> to the server, type the command
>
> passiv
>
> and then continue with your 'cd', 'dir' and whatever.
>
> >I also know it has something to do with the firewall and to be honest,
> >I don't even know if I have a firewall and if I do, it's nothing other
> >that what loads straight out of the box.
>
> One would hope you do - so here's a challange for you. See if you can
> find a copy of the Security-Quickstart-Redhat-HOWTO (if you have
> installed the HOWTOs, it should be in /usr/share/HOWTO/, or you can get
> it at any LDP mirror, such as
>
> http://en.tldp.org/HOWTO/HOWTO-INDEX/howtos.html
> http://ibiblio.org/pub/Linux/docs/HOWTO/
>
> >I also went through several HOW-TO's and most of them were either over
> >my head or need to be rewritten so the average person can understand
> >them.
>
> Honest, the HOWTOs are really written with the aim to be understandable
> and helpful. Some of them are written by people whose primary language
> is not English, but the people who review the documents try to help the
> author make them understandable. When you have nothing better to do,
> have a look at the LDP-Reviewer-HOWTO.
>
> >It would be nice if there is some easy way to get my command line ftp
> >session working so I don't have to log onto Windows (UGH) to put/get
> >my files.
>
> windoze has ftp? I stopped using it in 1992, and it didn't them ;-)
>
> Actually, as I understand it, windoze does default to passive mode,
> which breaks things in different ways.
>
> Hope this helps,
>
> Old guy

Thanks Old guy

Your comprehensive response was more than helpful.

I'm ftp-ing as we speak -- I was only one word away from success and
didn't know it. I guess I was looking for something much more
complicated.

The run down on active/passive was great and inspired me to read a
little more on the subject. Got a real handle on it now.

Also, looking over the security How-to docs that you recommend. Good
stuff.

Thanks again.

Jorge

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