Subj : DOStelnet u/l's by zmodem
To : All
From : Nancy Backus
Date : Tue Oct 12 2004 10:21 pm
* Crossposted from: F-DOSInterne
Some time ago, we were discussing the total impossibility of uploading
files and message reply packets using zmodem when telnetting with a DOS
setup, no Windows involved at all. I don't know if anyone is even
lurking here anymore besides me, but I wanted to let people know that my
resident wizard managed to accomplish the impossible, and now I AM able
to do zmodem uploads with my still totally DOS telnetting setup!!! I am
cross-posting this to BBS Internet, where it may also be appropriate, and
to Bluewave Support (where we recently were discussing this as well). :)
Let him tell you what he did:
--------------------------
I have had trouble finding a DOS TelNet setup that could send a file using
ZModem over the TelNet link. Being a laid-off professional programmer, I had
time to look into the problem.
Access to the source for the WATTCP libraries made it possible to look at
the logic, turn on debug functions not normally available, and see what the
problem is.
To keep the story short, peering at TCP packet traces and comparing them to
the ZModem and TelNet documentation finally led me to realize the problem is
caused by the TelNet IAC character (0xff). I was using TCPPORT as the TelNet
interface for CONEX, and TCPPORT doesn't escape the IAC character on sends.
It doesn't handle IAC sequences on receive very well either. The ZModem part
was working to specification, the TelNet part wasn't.
I ended up writing my own version and called it TNPORT. It uses the WAT2001
library (current 16bit library) - older ones don't work with my ISP.
I suspect that this problem is present in a number of DOS TelNet interfaces
as they often freely borrow from each other.
-------------------------------
I'm back... I've tested this now on all sorts of BBS software, and it
works consistently... Wildcat ver 4 and 5, Synchronet, Mystic,
Renegade, and Telegard are the ones that I have access to at the moment
and have tested it on. It works a lot faster than the kermit I had been
using for u/l's, too... :) He's uploaded his program to Chowdanet BBS
already, so it should be available there.
