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000052_news@columbia.edu _Mon Jan 17 19:55:57 2000.msg
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Subject: Re: MS-DOS Kermit, more capabalities
From: cangel@famvid.com
Message-ID: <VoOg4.6712$NU6.285660@tw12.nn.bcandid.com>
Organization: bCandid - Powering the world's discussions - http://bCandid.com
Date: Tue, 18 Jan 2000 00:24:22 GMT
To: kermit.misc@columbia.edu
On 2000-01-17 jaltman@watsun.cc.columbia.edu(JeffreyAltman) said:
JA>Newsgroups: comp.protocols.kermit.misc
JA>This is simply a brief follow up to address specific technical
JA>issues not touched by Frank's reply. -jea
JA>In article <011700040222not-2-disclose@the.net>,
JA><not-2-disclose@the.net> wrote:
N2> Isn't there any MS-DOS `Kermit' update in preparation that
N2> will offer `ZMoDem' file transfer capability?!
JA> No.
N2> What about the suggestion from Charles Angelich that
N2> `Kermit' should be able to "share" : the internal
N2> stack/~TelNet~ stuff with an external (`ZMoDem') protocol?!
JA> How could this possibly work is the single tasking
JA> environment of DOS?
JA> In 32-bit Windows, Unix, or VMS it is possible to run
JA> multiple programs at the same time because there is a task
JA> scheduler in the operating system. DOS does not have one.
First let me use the disclaimer that no one person can be
everywhere on the Internet nor can they sit at a variety of
computer terminals and be an expert on all of them. Having said
that ...
I was not recommending a multitasking function but since you
brought multitasking into the conversation ...
The multitasking is written into the application but DOS using
DoubleDos, Desqview, and others has multitasked for over a
decade.
If anyone at Columbia U. would be interested there are at least
two or three DOS telnet apps that do indeed multitask. DOSLynx
does this albeit not really well. NCSA telnet even mentions in
the docs that although it can maintain multiple windows
(connects) it is not adviseable to FTP in one and be using the
others.
YAN, a KA9Q variant, can FTP and continue to use it's other
windows (connections) with little difficulty even on an XT PC.
I've got it here and have done it while using EPPPD.EXE to
emulate an ethernet card and function as the packet driver for
YAN. If you do take time to install YAN you might also want to
take a look at it's handling of HTML and FORMS. Quite
impressive for a 16 bit app on an XT (if you _have_ an XT to
try this on). 8)
JA> In order for Kermit to be able to share the TCP/IP stack
JA> with an external Zmodem process it would be necessary for
JA> the Zmodem process to be built with internal support for
JA> the same networking features as are built into Kermit. This
JA> supposed Zmodem implementation does not exist.
Yes, actually it has been around for quite a few years now but
not in one application - two are required. FDSZ for the zmodem
and TCPPORT for the TCPIP stack.
FDSZ.EXE is scattered on many FTP servers in the USA and in
Europe. I've checked using ARCHIE servers. The 'F' is for
`fossil' and means it hooks the `int 14h' vector of DOS that
has been designated as the telecom vector since before DOS
v3.x. TCPPORT from the WATTCP package can supply the TCP/IP and
the `int 14h' vector that connects FDSZ.
These two apps have been in existence for about 8 years or
more. Seems no one realized they could be combined?
JA> Even if you could find a Zmodem implementation that
JA> implemented a TCP/IP stack, you would have the problem of
JA> how does Kermit transfer the state of the TCP/IP and Telnet
JA> state machines from one process to another.
I suggested an `int 14h' vector reset to point to the TCP/IP
routines in MSKermit.
JA> The answer is that it is not possible to use an external
JA> protocol implementation over TCP/IP socket. The only way
JA> that Zmodem could ever be used is if it were built into
JA> Kermit.
The TCPPORT.EXE from the WATTCP package can do exactly what you
think cannot be done if you use FDSZ.EXE from Omen Tech.
TCPPORT connects to the 0x60 hook of EPPPD, supplies the TCP/IP
stack, and resets the `int 14h' vector to point to TCPPORT.
FDSZ thinks it's talking to DOS.
If MSKermit did a vector reset of `int 14h' to point to it's
TCP/IP send_char(), receive_char() and returned dummy `OK' data
to other requests (in the AX register) then FDSZ would happily
load and execute thinking it was sending / receiving through
the original DOS vector. The code to accomplish this is
relatively small (30 lines of code or less?).
If you take a look at TCPPORT.C in the WATTCP package (it's
quite small) and look near the end of the source code you will
see the required `hooks' and dummy replies required to make
FDSZ or other apps think they are hooked into DOS. Short,
simple, no big deal really.
This works for downloading, I do it every day. Uploading is a
bit trickier hence my original questions regarding the WATTCP
package. I need to make some adjustments in the TCPPORT code to
understand XON/XOFF so that FDSZ can upload (FDSZ has no
`handshake' command as DSZ does). I thought that while I am
doing this I might improve the speed and stability by comparing
the functions in MSKermit send / receive to those in TCPPORT
(since MSK is some order of magnitude faster and smoother in
operation).
JA> As we have stated previously, no one at the present time is
JA> working to implement Zmodem in MS-DOS Kermit. If you want
JA> to implement Zmodem in MS-DOS Kermit be our guest. The
JA> source code is available. However, as the source code is
JA> copyright you must submit your changes back to Columbia
JA> University for distribution. You cannot distribute the
JA> altered software yourself.
I might try to vector the `int 14h' into MSKermit to allow
`fossil apps' to function as external events but if I was to
implement a full zmodem send / receive Columbia would have to
buy it from me or live without a copy. 8) Money can be _so_
important when man-hours are a part of the equation.
N2> I discovered that i could access my ~SMTP~ server on ~IP~
N2> port #25 but `Kermit' is the only program not to allow me
N2> such access if i try! Why?
JA> Spoofing is just what you think it is. It is someone
JA> sending mail via an e-mail address which either does not
JA> belong to them. The usual purpose is to SPAM or commit
JA> fraud. Are there other ways to do this? Yes. But a decision
JA> was made a long time ago that MS-DOS Kermit should not be a
JA> tool that could be used for this purpose. Therefore, port
JA> 25 is blocked.
I always imagined a bored employee sitting at a terminal
somewhere fiddling with the keyboard trying to look busy using
these stupid tricks to fill an otherwise empty headed existence
that dedicates his / her life to learning how to fowl things up.
You've either done everyone a favor or become CyberCop. Either
way I have no idea what `spoofing' is and don't really care
very much.
I would like to have external protocols function with MSKermit
- that would not be wasted time IMO. Who knows, there may be
another new protocol in a few years that we would all like to
try out without writing an entire application just to try it? 8)
The source code being written _only_ for MSC and MASM means
that I'm not going to be able to help a great deal any time
soon. I would have to first convert the code to compile here
and _then_ attempt to implement the vector reset of `int 14h'.
8(
>
> , ,
> o/ Charles.Angelich \o ,
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