From: "Steven Levine" <ecs-isp@2rosenthals.com>
Message-ID: <66fb19e5.23.mr2ice.fgrirsq@earthlink.net>
Date: Mon, 30 Sep 2024 14:36:37 -0700
To: "eCS ISP Mailing List" <ecs-isp@2rosenthals.com>
In-Reply-To: <list-11054921@2rosenthals.com>
Subject: Re: [eCS-ISP] FTP problem

In <list-11054921@2rosenthals.com>, on 09/30/24
   at 05:05 PM, "Lewis G Rosenthal" <ecs-isp@2rosenthals.com> said:

Hi all,

>Surely. As good a place as any.

There's always Peter's FTPServer list, but it seems that almost everyone
is on all the lists and the lists are low traffic, so it really does not
matter, IMO.

>Bear in mind that the Zeitgeist is that FTP is evil. It is quite possible
> that a router along the way blocked your FTP traffic.

While it's possible, the failure's I've seen are typically something else. 
Most often a firewall requires the client to toggle between active/passive
mode.  Another less likely case is that the ports specifed for use by
FTPServer don't match the open ports.  See Setup->Options->Restrict PASV
data port numbers.

>difficult to  determine which intervening hop is blackholing your
>traffic. tracerte uses  UDP, so even specifying the port (tracerte -p 21)
>may not get you reliable  results (timed out for me around hop 12, even
>specifying a longer wait time).

My experience is that tracerte fails more often than not these days.  The
routers are not configured to support it.  My workaround is

  telnet ftp.foo.com 21

This tests if a connection is even possible.  It takes login issues and
data port issues out of the mix.

If you want a bit more data, iptrace can provide some.  On the client end
it will show you if the SYN packet gets a response.  On the server side it
will show you if the SYN packet ever makes it to the server.

Steven

-- 
----------------------------------------------------------------------
"Steven Levine" <steve53@earthlink.net>  Warp/DIY/BlueLion etc.
www.scoug.com www.arcanoae.com www.warpcave.com
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