On 6/28/20 3:54 AM, R.Wieser wrote:
> :-) Which is what my initial question started with.   Should I just
> plug a ethernet dongle into an USB port, or are other (and perhaps
> better) options available ?

There are a number of options.  Some are more practical than others.

> Second, how do handle (configure) such an extra interface ? Especially
> as I do not want either interface to be able to talk to the other
> without my say-so.

Adding an additional network interface to a Linux machine is fairly
easy.  Configuring said Linux machine to not forward traffic between the
two interfaces is also relatively easy.  (Linux itself defaults to /not/
forwarding.  But some distributions change that.)

> Are there (open source, sourcecode) programs available which will
> handle such (very restriced) communication ?

That makes me think that you want hosts A and C to communicate with each
other across some routed network.  This differs from my previous
understanding of what I thought you wanted.  I thought you /explicitly/
wanted hosts A and C to NOT be able to talk to each other at all.
Further, that any ""communications (read: exchange of files / etc.)
would be done but putting files in a common location, B.

> As I said, I'm a rather newbie in regard to both Linux as well as
> the RPi.  I could do worse than to work my way thru a tutorial or
> get my (rather needed) pointers from someone elses project.

Welcome.

If anything, Linux, and the Raspberry Pi suffer from too many options.

> :-)  Although I know of the latter by way of what Windows offers (SMB),
> I have no idea what exactly the SAMBA service does or how I should/need
> to configure it.   Let alone which things I all need to disable to
> be sure no inadverted connections can be made between the interfaces.

Typically, in scenarios like the one you're asking about, it's okay if
the services listen on multiple interfaces on B.  The purpose is to
prevent A and C from being able to talk to each other directly.  So, A
talking to B on the AB interface is fine, as is C talking to B on the BC
interface.  There usually is no harm in something like Samba listening
on multiple interfaces.  Presuming you are using the same protocol on A
and C, in some ways having Samba (et al.) on B listen on multiple
interfaces is required.

> Last, but certainly not least, I have no problem with trying to whip
> up something myself.  In fact, that is pretty-much where my hobby lies.

:-)

Learning opportunities are good.  But you may want to avoid painting
yourself into a corner and making things harder on yourself than is
strictly necessary.  Why re-create programs if you can use existing
programs.  Especially if said existing programs will happily work with
the isolation that you desire.



--
Grant. . . .
unix || die

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