Re: [Linux-decnet-user] DECnet for Linux on Ubuntu

[Gary L. P. <tiv...@gm...>]

Thanks for the information.

I rather doubt that upstart has anything to do with your problems,
since 10.04 uses it too. I haven't tried DECnet on 10.10 but I have a
laptop with 10.10 so I'll try installing it there and see what
happens.

There have been statements made that the Linux kernel no longer
supports DECnet or, more specifically, that "DECnet support in the
kernel is dead" whatever that means. Those started with versions of
the kernel much earlier than the one I am running. I have kernel
version 2.6.32-32-generic on both Linux systems that are currently
working with DECnet.

As long as existing kernel code is not stripped out, this shouldn't
matter too much, as DECnet itself hasn't changed very much for years
now, and the DECnet on Linux code uses Phase IV which hasn't changed
in more than a decade I think.

One thought on your problem with being restricted just to your local
LAN. DECnet Phase IV does change your hardware MAC address. Within the
local network, this shouldn't matter for more than a minute or so
because the arp databases will age off the old information and pick up
the new address. However, network switches and routers can be slower
to act on a change of that sort. Depending on security requirements at
your installation, they may in fact refuse to recognize a new MAC
address that has not been registered or approved. This can be
remedied, since the substitute address that Phase IV assigns is
predictable based on the Phase IV network address in use.

I'll check on Ubuntu 10.10, since I can easily do that, and report back here.

I can understand how LAT might be all you need, as it was also
recommended to me. But I have other uses for the DECnet protocol and
already had terminal style connections working over TCP/IP and through
serial port emulation. I'm particularly interested in getting X11
working over DECnet, which was apparently possible at one time, but
the links to the code and information on the Sourceforge site are
stale now and go nowhere.

--Gary

On Sat, Jun 25, 2011 at 5:31 AM, Bengt Nilsson
<ben...@ch...> wrote:
> I guess I am the source of this item.
> The story is like follows:
> I needed terminal access from Ubuntu to a very old VAX/VMS 5.5-2H system.
> I installed decnet on a small desktop with Ubuntu 10.04 LTS, working fine.
> After upgrading to 10.10, the response to "dnlogin" was
> bnilsson@ubuntu:~$ dnlogin fyvax7
> Cannot connect to fyvax7: Rejected by object
> I reported it to this forum, and I got some suggestions, but no real
> solution in the beginning.
> The docs say that decnet must be started before the tcpip networking, and I
> suspected that the new "upstart" boot method was changing the order of
> things between 10.04 and 10.10.
> Upgrading to 11.04 did not improve the state of this behaviour either.
> On the forum, I got the suggestion to shut down the network, start decnet
> and restart the networking.
> This worked, I could again use "dnlogin" to connect to my VMS system.
> However, my tcpip now had only access to my own subnet, why, I do not know.
>
> Finally, I got the suggestion to skip decnet and use LAT instead.
> For the things I need to do, this was a better solution, without any bad
> side effects as far as I can see.
> So decnet is now removed from my desktop Ubuntu 11.04, I use "llogin"
> instead, and all is working fine.
> I will not put any more time into decnet to make it work for me, at least
> not for the time being.
> It seems the installation and startup methods for decnet need some tuning
> before it can be used with the current Ununtu.
> Someone with more knowledge than me need to take the time to intall Ubuntu
> and investigate what is going on. I was surprised to get the answer from the
> developers(?) that "we don't use ubuntu"  and that was it. As Ubuntu is
> coming to be more or less mainstream, I would assume it needs to be paid
> attention to.
> Incidentally, I can mention that I did the network stop/decnet start tests
> on virtual Ubuntu 11.04 on a VMWare Fusion on my Mac, and that's how I found
> that it was working before I transferred this method to my real desktop
> Ubuntu. So setting up a test system does not need to be a great effort, a
> virtual machine will probably work fine.
>
> --
> Bengt Nilsson
> Nanofabrication Laboratory,
> Department of Microtechnology and Nanoscience,
> Chalmers University of Technology,
> SE-412 96 Göteborg, SWEDEN
> e-mail: ben...@ch...
> tel: +46-31-7728480
>