[HECnet] Connections?

[dwe-6006 at philtest.org]

I'm not using any NAT on the SIMH side.  Since the hosting provider assigned a single IPv4 address to the virtual PC instance, by definition SIMH couldn't use a different one and still be reachable from the Internet. By adding a second routable address to the virtual PC's interface, and using one for host access and the other for guest (SIMH) access everything works just as planned.  The LAN segment's router has two ARP table entries with the same MAC address and different IPv4 addresses but that it not unusual. 

Dave

-----Original Message-----
From: owner-hecnet at Update.UU.SE [mailto:owner-hecnet at Update.UU.SE] On Behalf Of Mark Pizzolato
Sent: Saturday, May 5, 2018 12:18 PM
To: hecnet at Update.UU.SE
Subject: RE: [HECnet] Connections?

On Saturday, May 5, 2018 at 3:11 AM, Dave wrote:
> OP here, if both the host and the SIMH guest are listening for SSH 
> traffic on the same interface / IP address then only one of them is 
> going to make the connection. Since the SIMH guest is the last to register, it gets the traffic.

A simh guest and the host system may be transiting traffic through the same physical network interface, but they each are using separate (unique) MAC and IP addresses for their traffic.  As such this analysis is incorrect unless you're using a more complicated NAT setup on the simh side.  NAT is more complicated due to the need to setup NAT for a specific incoming port mapping which must be unused on the host system.  Doing this SSH into the guest would be possible, but not really related to the original discussion.

- Mark

> On Saturday, May 5, 2018 at 3:27 AM, Johnny Billquist 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             ||  Reading murder books
> pdp is alive!                     ||  tryin' to stay hip" - B. Idol
>