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000029_hvanclee@nyx.net_Mon Oct 21 11:15:27 EDT 2002.msg
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Article: 13792 of comp.protocols.kermit.misc
Newsgroups: comp.protocols.kermit.misc
Subject: Re: Problems transferring over ppp connection
References: <1034801647.495773@irys.nyx.net> <m1n0pab9d2.gnus@usa.net> <1035092921.407864@irys.nyx.net> <aouo2c$rc0$1@watsol.cc.columbia.edu>
Organization: Nyx, Spirit of the Night
X-Newsreader: trn 4.0-test76 (Apr 2, 2001)
From: hvanclee@nyx.net (Henry van Cleef)
Originator: hvanclee@nyx.net (Henry van Cleef)
Message-ID: <1035199157.27507@irys.nyx.net>
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Date: 21 Oct 2002 05:18:18 -0600
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Xref: newsmaster.cc.columbia.edu comp.protocols.kermit.misc:13792
In article <aouo2c$rc0$1@watsol.cc.columbia.edu>,
Frank da Cruz <fdc@columbia.edu> wrote:
>In article <1035092921.407864@irys.nyx.net>,
>Henry van Cleef <hvanclee@nyx.net> wrote:
>
> (More about Kermit vs Netscape file transfers over a PPP connection.)
>
(snip)
>Of course we realize this doesn't always happen, which is why Kermit has
>so many user-level adjustments: streaming vs Ack/Nak; packet length,
>window size, various adaptations to lack of transparency. Kermit can't
>see though the TCP layer to get at the datalink layer or physical devices.
>If they are not doing their jobs, then you have to step in and either fix
>them or else scale back on Kermit's performance settings.
>
>As to why Netscape transfers work and Kermit ones don't, I'm sure this
>could be pinned down given enough evidence, such as TCP packet traces.
>Once you see the characteristics of the HTTP data transfer, you could
>adjust Kermit to the same characteristics and it would work the same way.
>
Thanks for the comments. I've had a chance to do enough experimenting
and testing to have homed in on a few things.
1. Setting nocpp in the pppd options to prevent software compression
made a huge and consistent difference.
2. Eliminating ssh from the stream by using a straight telnet, after
killing compression, now makes Kermit work "just like downtown."
So it turns out that the major issues were in the transport layer, not
in Kermit. So far as I know, Netscape doesn't use encryption in
downloading---would be essentially the same as working through telnet.
And it is also becoming obvious to me that I've got some problems at
the Radius end of things with ssh---it tends to lock up from time to
time just trying to read Usenet. So of course it isn't going to
support a file transfer through anything.
At this point I'm satisfied that the problems I need to chase have
nothing to do with Kermit itself. And thanks for the tutorial---it
may seem like something of an exercise at your end, but just walking
through the basics has suggested that I refresh my memories of packet
communications in general---it's only been 20-25 years since I thought
about any of this stuff.
Hank