[HECnet] Apples MAC OS X pcap library...

[Johnny Billquist]

Hi, Jean. Looks like we could have some fun... ;-)

Jean-Yves Bernier wrote:
At 7:59 PM +0100 2/15/10, Johnny Billquist wrote:
I'll try with a cable tonight to see if that works better than wireless...
I was busy unprotoizing some C sources to feed the pre-ANSI DECUS C
compiler. Since I see you are working on the bridge, I have made some
further tests tonight.

Hmm. The DECUS C compiler have some nice corners, but much of it is a
headache. I'm trying to remember if I ever published all my patches and
fixes for it. I made it work fine with split I/D-space, extended it a
little, and fooled around in general a number of years ago...

One thing I forgot to mention in my previous mail : On Mac OS/darwin, eth0
is enO.
So, bridge.conf must contain   'local en0'.

Correct. And en1 is normally the wireless port, but these can be changed
if the user is "creative".
However, it is just a string in the config file, so the most important
thing is just to get it right, and then you don't have to think about it.
In NetBSD (for instance) the ethernet ports can be many different
strings, but most definitely are not ever either eth<n> or en<n>. So it
can differ by a lot depending on what OS you are using.

The program I use is not your bridge but a very similar one, intended to
see how much work it would be for a Unix box to pretend to be a DECNET
node. Indeed, I copied your pcap initialization part, filter included, then
added my code.
Assume
machine A running node 1.1,
machine B running node 1.2,
machine C running nothing,
all on a wired, switched LAN.
When my program is running on machine C, I see all broadcast packets:
  Router-hello l2rout (DECNET packets, size 60)
  Lev-1-routing (DECNET packets, size 386 and 590x)
  Lev-2-routing (DECNET packets, size 152)
  A few LAN packets, size 60.
Since I am on a switched network, I see none of the unicast packets, for
example when I initiate a DECNET transfer between A and B.
When my program is running on machine B, I see:
  Same packets as above (pcap_setdirection was called with PCAP_D_INOUT).
  Packets identified as data, data-ack, link-service, ils-ack by tcpdump.

That is only as to be expected, and you cannot draw any conclusions from
that. Since you have a switch, it will only forward unicast packets to
the port where the actual recipient is located, as soon as it have learned.
This is all based on mac addresses.

On my machine I have, as I have written, noticed that the packets I see
with tcpdump differ from the packets I see in the bridge.
These are all broadcast packets, by the way...

Until now, I have not seen a packet in tcpdump I have not seen in my
program, which is basically yours for the pcap part. By the way, I'm
looking for a document describing DECNET frames to dive a little deeper in
that way. Any pointer will be appreciated.

The whole basics of DECnet is in the public domain. Look through
bitsavers for instance. Or just google for the documentation.

All tests use Apple's libpcap.dylib in /usr/lib, NOT libpcap.a in
/usr/local/lib which was required to install simh on Mac OS X. I'm running
Tiger, so you should have no problems using Leopard.

Yes, unless some problem have been introduced in Snow Leopard... :-)

Well, I realize that this is my first contribution to this list and maybe a
short introduction is due. Here we go...
I have been working with RSX-11M from '80 to '87. First in computer music
research (GRM, Paris), then in pre-press/phototypesetting. Some old systems
have been donated to me, noticeably SMS (Scientific Micro Systems) OEM
LSI-11/73.

Fun!

As a hobby project, i've resurrected these systems, then linked them to
simh via DECNET. A few details of the project here, unfortunately in french
but I'm sure you will enjoy SEAGATE surgery http://www2.pescadoo.net/pdp/
and maybe DC600 meltdown:
http://www2.pescadoo.net/pdp/photos/TANDBERG/P1010012.JPG
Unfortunately, any interesting RSX software I could share (yet another full
screen editor, a hierarchical filesystem for RSX and some funny drivers)
are locked on a set of magtapes I did not manage to backup before the day
tape drives lifted off earth for an secret destination. So is life...

If you have 1/2" tapes you want read, I can do that.
I have a 11/70 with a TU81 ready for such occasions. :-)
(That's MAGICA:: by the way - (1.1))

More editors would always be fun. As for hierachical file system, I have
a patch set for RSX to get full hierachical file system support. The
ODS-1 structure don't have any problems with that, so it's mostly a
qustion of changing the reserved size for directory strings, and
changing the directory lookup routine in FCS, and some filename parsing
code.

I originally did that work for RSX-11M-PLUS V4.3, but have applied it to
4.6 as well. It should be on ftp:://ftp.update.uu.se/pub/pdp11/rsx if
you look around.

	Johnny

-- 
Johnny Billquist                                   || "I'm on a bus
                                                                  ||   on a psychedelic trip
email: bqt at softjar.se                         ||   Reading murder books
pdp is alive!                                         ||   tryin' to stay hip" - B. Idol