On 2020-06-29, R.Wieser  wrote:
> Ahem,
>
>> The Pi provides the illusion of a transparent connection between
>> A and B but in reality intercepts, filters and potentially modifies
>> any and all traffic between them.
>
> Not quite.   My basic idea was/is to have the Pi to respond to a connect
> request on a single port only, and than, when both sides have connected
> (their actions, not the Pi's), transfer datapackets from one interface
> (socket) to the other.

That's a pretty good description good - now read Stevens book on unix
networking programming (other books are available) and write your
program!

I can't see what's stopping you.

Sometimes I think you enjoy more discussion instead of actually googling
around/reading and getting the job done.

There's a newsgroup for unix programming where are more specific
questions can be asked.

And before you say anything - in this context "unix" = "linux".

>
> Yeah, its an absolute minimal approach.   Any-and-all "filtering" is
> actually done as part of a sockets normal behaviour. :-)
>
>> This is done with the firewall capabilities of Linux and is as
>> complex as you want to make it plus about 10% usually.
>
> I mentioned somewhere earlier that I have my reservations about that kind of
> filtering.  To easy to forget to exclude a port or not filter certain data
> and you're SOL..
>
> But yes, its also something to look into.    Heck, there is /so much/ I can
> look into that I really need to secure myself a life extension to visit it
> all ! :-)
>
> Regards,
> Rudy Wieser
>
>

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