[HECnet] Connections?

[Mark Abene]

Thank you, Johnny, that's what I was referring to.


On Sun, May 6, 2018, 4:32 AM Johnny Billquist <bqt at softjar.se> wrote:

> What Mark actually is talking about, and referring to, is the question
> if sending packets are also seen by others connected to the same
> interface and receiving packets.
>
> It's a bit more complicated than just saying "BSD" does this, or "Linux"
> does that. But the bottom line is that some systems, and some hardware,
> makes outgoing packets also visible to programs reading from the
> interface, and other combinations do not.
>
> And if you do not receive outgoing packets, then two virtual machines on
> the same host, using the same interface, cannot communicate with each
> other.
>
>    Johnny
>
> On 2018-05-06 04:00, Mark Pizzolato wrote:
> > Mark,
> >
> > I’ve seen no evidence that anything has changed at all on Linux or other
> > operating systems.   Changes have been made within simh to better
> > support some situations where bridges are used, but some sort of bridge
> > setup needs to be done like it did long ago.
> >
> > Please point at specifics of what you are seeing that now allows telnet
> > to an emulator’s IP address without setting up some sort of bridging.
> >
> > -Mark
> >
> > *From:*owner-hecnet at Update.UU.SE [mailto:owner-hecnet at Update.UU.SE] *On
> > Behalf Of *Mark Abene
> > *Sent:* Saturday, May 5, 2018 3:57 PM
> > *To:* hecnet at update.uu.se
> > *Subject:* Re: [HECnet] Connections?
> >
> > Nothing of the sort. I'm saying that in the past, you couldn't telnet to
> > an emulator's IP address from within the same host server. Naturally the
> > host server has multiple IPs for all the emulated guest OSes. This was a
> > well known and well documented peculiarity of BSD and Linux when logged
> > into a shell on the host server. It's no longer the case on more recent
> > Linux systems.
> >
> > -Mark
> >
> > On Sat, May 5, 2018, 10:56 AM Mark Pizzolato <Mark at infocomm.com
> > <mailto:Mark at infocomm.com>> wrote:
> >
> >     Hi Mark,
> >
> >     I’m not understanding what you saying here.
> >
> >     Are you suggesting that on a single host system, you’ve got multiple
> >     independent simulators running which all are using the same IP
> >     address as the host system? And, if true these devices can then, not
> >     only uniquely communicate with remote systems (on the Internet say),
> >     and also to each other AND the host system?
> >
> >     -Mark
> >
> >     *From:*owner-hecnet at Update.UU.SE <mailto:owner-hecnet at Update.UU.SE>
> >     [mailto:owner-hecnet at Update.UU.SE
> >     <mailto:owner-hecnet at Update.UU.SE>] *On Behalf Of *Mark Abene
> >     *Sent:* Saturday, May 5, 2018 10:45 AM
> >     *To:* hecnet at update.uu.se <mailto:hecnet at update.uu.se>
> >     *Subject:* Re: [HECnet] Connections?
> >
> >     This is an often misunderstood generalization, with some people able
> >     and others not. I remember this being true on *BSD. You could not
> >     connect to a simulated IP on the same host. It *used* to also be
> >     true on Linux, but is no longer the case for some time. On my ubuntu
> >     server where I run dynamips, simh, and klh10, all on bridged taps, I
> >     can telnet to all instances, even locally.
> >
> >     -Mark
> >
> >     On Sat, May 5, 2018, 12:27 AM Johnny Billquist <bqt at softjar.se
> >     <mailto:bqt at softjar.se>> wrote:
> >
> >         On 2018-05-05 03:39, Robert Armstrong wrote:
> >          >>since once Multinet grabs the interface, I can’t get to the
> >         underlying
> >          > host.
> >          >
> >          >    Actually I think it’s a limitation in simh and the pcap
> >         library – the
> >          > simh guest OS can’t talk to the host OS on the same
> >         interface.  You can
> >          > work around the problem with a TAP device.  Check the
> >         archives for the
> >          > simh mailing list – it’s been discussed many times before.
> >
> >         No. That is not correct. I run simh myself on a machine where I
> >         have
> >         both the native host and simh talking on the same ethernet. And
> >         they are
> >         both reachable by other hosts.
> >         The OP must be doing something else funny.
> >
> >             Johnny
> >
> >         --
> >         Johnny Billquist                  || "I'm on a bus
> >                                             ||  on a psychedelic trip
> >         email: bqt at softjar.se <mailto:bqt at softjar.se>             ||
> >         Reading murder books
> >         pdp is alive!                     ||  tryin' to stay hip" - B.
> Idol
> >
>
> --
> 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
>
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