RE: dhcpcd not working in simh-vax with xq0:nat networking

[Mark Pizzolato - Info Comm <Mark%infocomm.com@localhost>]

On Friday, December 10, 2021 at 1:47 PM, Mark Pizzolato wrote:
> On Friday, December 10, 2021 at 12:57 PM, Mark Pizzolato wrote:
> > On Friday, December 10, 2021 at 12:07 PM, Rhialto wrote:
> > > On Fri 10 Dec 2021 at 19:48:43 +0000, Mark Pizzolato - Info Comm wrote:
> > > > I will track this down if you can provide me with a pointer to a disk
> image
> > > > (hopefully compressed) that demonstrates the problem.
> > >
> > > Thanks! I was thinking in first instance it would be a NetBSD weirdness,
> > > but maybe it isn't. I only tried the microvax3900, not other models.
> >
> > It may be NetBSD weirdness, or it more likely a general weakness in the
> > dhcpd in the simh NAT code.  The NAT code comes from what was originally
> > slirp.  The NAT dhcp activities under simh haven't generally gotten much (if
> > any) exercise since I think that only NetBSD has a dhcp client.  Maybe
> > Johnny's RSX TCP stack also has a dhcp client, but users probably haven't
> > been
> > using NAT.
> >
> > As I start to think about this and the digging you already did that observed
> > that
> > it worked when tcpdump put the qt interface into promiscuous mode, I'm
> > thinking that the default QT initialization of the XQ device isn't configuring
> an
> > appropriate MAC receive address that would match the destination MAC
> > address of the slirp dhcp's DHCP response packets.  I haven't looked yet,
> but
> > maybe the slirp dhcp response packets may have a broadcast destination
> > address and the interface may not be yet configured with a broadcast
> > address in its match list.
> >
> > I'll let you know what I find.

A relatively minor fix to the slirp dhcp logic is now committed to the simh 
master branch.

Let me know if still have problems or more in the future.

- Mark