[Simh] DECnet for TOPS-10

[Johnny Eriksson]

<r.jarratt at computer.org> wrote:

> That has got to be worth integrating into the latest SIMH. Does that mean we
> can get DECnet running on TOPS-10 on SIMH? I would love to know how you
> actually install and set it up on TOPS-10.
> 
> I will try to find some time to get the KMC/DUP into the latest SIMH.

You are welcome.  A number of random points:

* My code sends the DDCMP frames out as UDP datagrams, and receives
  frames the same way.  You simply specify src/dst ports, and possibly
  an address (defaulting to 127.0.0.1).  This means that there is no
  need to do elaborate (blocking) setups of TCP connections etc. from
  inside the simulator.  This also makes it trivial to connect two
  simulators running on the same machine, or on the same (trusted) LAN.

* A side effect of this is that you can have a helper process on your
  machine that does the TCP magic and also encrypts the traffic out
  on the evil internet.  My normal (at the moment defunct) setup is
  done that way.  One such program is on the site, named "stuk2.c"
  (don't ask...)

* You can in theory write a helper process to talk to some real
  piece of hardware.  I have not tested, but it should work to send
  the frames to a serial port and connect it to a real machine
  running async DECnet on a terminal line...

* The current crypto in stuk2 is weak.  Not the algorithm itself,
  RC4 (tm) is used, but some random padding etc. should be applied
  on the data stream, since it normally consists of 6-byte idle
  frames, with mostly known bits...

* The actual KS10 supports one KDP with 2 DUPs.  There are several
  reasons for this, like unibus load, unibus space and speed.  This
  places some limits in case one wants to build a network of emulators
  and want to run both ANF and DECnet.  The KMC itself supports 16
  if I remember correctly.  We should have at least 6-8, and allow
  for a fairly simple mod to Tops10 to handle them.

* I am willing to help out, but I have very limited time until after
  the CuG conference, mid May.

> Regards
> 
> Rob

--Johnny