Subj : Re: Weekly nodelist report on noteworthy changes (108)
To   : Tommi Koivula
From : Wilfred van Velzen
Date : Fri May 02 2025 17:38:51

Hi Tommi,

On 2025-05-02 17:52:18, you wrote to me:

 TK>>> How did you test? That's not IVM in port 2030, it's ITN.
 WV>>
 WV>> I'm not testing the protocol. I just connect to the advertised port
 WV>> with telnet, and report on what I see. ;-)

 TK> You were lucky this time, you were using telnet to connect vmodem, but it was
 TK> telnet server indeed. ;)

See below.

 WV>> What is IVM anyway? There are only a few minimal mentions of it in
 WV>> the FTSC docs:
 WV>>
 WV>>
 WV>> FRL-1016:
 WV>>
 WV>> 1.1.8.4.  IVM[:3141]
 WV>>           Vmodem protocol according to Ray Gwinn's SIO-package
 WV>>           for OS/2

 TK> From the SIO v1.60 docs:

 TK> === Cut ===

 TK>                                  WHAT IS VMODEM

 TK>      Vmodem is a software implementation of a modem, referred to as a
 TK>      Virtual Modem.  Basically, it attempts to fake out other software
 TK>      (like terminal programs) into believing they are accessing a real
 TK>      modem.  Vmodem will turn any Terminal into a Telnet Client, and any
 TK>      BBS into a Telnet Server.

 TK>      Normal (real) modems provide an interface that allows terminal
 TK>      programs to pass digital information across telephone lines.  Vmodem
 TK>      does the same thing from the application (terminal) program's point of
 TK>      view.  However, the other side of Vmodem is not a phone line, but a
 TK>      digital network like Internet.  Thus, Vmodem allows the hoards of
 TK>      communications programs to pass information across Internet instead of
 TK>      using phone lines.

 TK>      In addition to acting as a Telnet server, Vmodem uses a newly designed
 TK>      protocol for communications networks, called the Virtual Modem
 TK>      Protocol (VMP).  At this time, no other programs have implemented VMP,
 TK>      thus Vmodem is required on both ends of the connection to use the VMP.
 TK>       However, VMODEM.EXE will accept inbound Telnet connections from any
 TK>      system, meaning a BBS under vmodem can be accessed by just about
 TK>      anyone with an Internet connection.

 TK>      Future implementations of Vmodem may access networks other than
 TK>      Internet and use TCP/IP implementations other than IBM's.  The current
 TK>      implementation of Vmodem works only on Internet, using the Internet
 TK>      Access Kit (IAK) that is included with OS/2 V3 and IBM's TCP/IP (for
 TK>      OS/2) version 2.0, with the August 1994 CSD applied.

 TK>      A single invocation of Vmodem can service all of the Internet ports
 TK>      defined in the SIO command line.

 TK> === Cut ===

If I read that correctly IVM is just an extension of ITN with VMP. So IVM implies ITN by default.

 WV>> FTS-5001:
 WV>>
 WV>>    IVM     3141  Vmodem connection using FTS-1 or any other protocol
 WV>>                  designed for classic POTS and modem.
 WV>>
 WV>>
 WV>> Wouldn't the node qualify for IVM under the FTS-5001 "definition" ?

 TK> Yes. SIO/VModem can accept telnet and vmodem calls. By default ports ITN:23
 TK> and IVM:3141.

So I wasn't lucky my simple telnet test worked... ;-)


Bye, Wilfred.

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