On Sun, 28 Jun 2020 11:54:16 +0200, "R.Wieser" 
declaimed the following:


>
>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.
>

 They can't, unless you configure each to be a routing gateway for the
other -- that's what "internet connection sharing" on a Windows box is
doing (and whatever the equivalent on Mac/Linux would be).

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

 You still aren't clear on WHAT this communication IS... File transfers
to the R-Pi with no knowledge of any other systems... FTP/sFTP both require
the external systems to connect to the R-Pi to move files between them and
the R-Pi -- they do NOT move files /through/ the R-Pi to other external
systems.

 NFS/Samba is similar -- in that whatever "share" (a directory on media
mounted on the R-Pi) is made network shareable. The difference is that
FTP/sFTP requires explicit GET/PUT operations to move files around, while
network shares are "mounted" on each external device and whatever native
file manipulation commands are available can be used (including editing
files that on the share).


--
 Wulfraed                 Dennis Lee Bieber         AF6VN
 wlfraed@ix.netcom.com    http://wlfraed.microdiversity.freeddns.org/

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