Re: ftp problem

If my problem is a restricted group of ports, that may explain the
sometimes works/not works. And my stop/start is really doing nothing.
My next try goes for another port (that may not be restricted).
I have sent this whole thread to net admin who is the contact for the
isp firewall (a "managed T1").
I do appreciate all the explanations that have made this very clear
how the process works.
jim

----- Original Message -----
From: "Scott Klement" <klemscot@xxxxxxxxxxxx>
To: "Midrange Systems Technical Discussion" <midrange-l@xxxxxxxxxxxx>
Sent: Tuesday, July 29, 2003 12:56 PM
Subject: Re: ftp problem


>
> Did you upgrade the server's software when you did this?   Change OS
> versions, or FTP software?  Or, change your router/firewall in some way?
>
> Each file transferred via FTP opens a new connection on a new port.   The
> FTP client sends the PORT command to the FTP server to tell the server
> how to connect to the client so that it can open this new connection.
> The fact that you never see a 150 message means that it's unable to
> establish the connection that the client/server have agreed upon.
>
> The client will typically choose a new/available port for every single
> connection, letting the TCP/IP stack choose which port is available, and
> then will send the new port number.
>
> >From the symptoms you list, I would assume that some of the possible
ports
> are being blocked by a firewall or NAT.   It's possible if you changed
> either the OS or the FTP software that the "range" of ports that FTP uses
> has changed.  If that's the case, it would explain why the upgrade would
> change the behavior.
>
> The easiest thing to try (which may or may not help) would be using
> passive mode for your FTP.   Simply specify passive in your batch file,
> and see if that helps.
>
> The thing that really puzzles me is the need to stop/start the FTP server.
> The whole idea that the FTP server stops working and needs to be
> started/stopped just because of a network error is not a good sign.
> That's a bug that should be reported to IBM.  I'm sure that IBM wants
> their server to be as stable as possible!
>
>
> On Tue, 29 Jul 2003, Jim Franz wrote:
> >
> > At V4R5 I have a site I FTP to from an offsite pc, using a batch file &
> > WinXP, every week, 2 diff files.
> > Working for years. After a "network upgrade", the FTP is sometimes
> > "hanging" and won't work till i stop/start the FTP server. (have latest
cume)
> > ftp logs on
> > 200 PORT subcommand successful    and hangs there...
> >          never get 150 Sending file......
> >
> > I can see FTP job QTFTPxxxxx and nothing odd in log.
> > In exit program log i can see the SET and GET, just like successful one
> >
> > Happens about 1 out of 4 tries, but once happens, must reset FTP server.
> > Any ideas?
> > jim franz
> >
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