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Re: TCP proxy for host on subnet

On Tue, Jun 06, 2017 at 10:59:30AM +0100, Ron Leach wrote:
> On 05/06/2017 14:08, Henning wrote:
> >
> >socat
> >
> Henning, thank you for that.  socat seems a very flexible package.
> Have you used it yourself, at all?  I couldn't see from the documentation

Yes I connect a serial port over network.

> how to terminate socat.  I was planning to use a variation of one of their
> examples, like this:

terminate in terms of "stopping"? I think SIGHUP will work.

> socat -d -d -lmlocal2 \
> TCP4-LISTEN:3129,su=nobody,fork,range=,reuseaddr \
> TCP4:name.server.tld:4444
> I was also unsure whether socat would hold open a connection to
> name.server.tld even if no transactions were taking place, or whether socat
> would only open the connection each time traffic arrived on 3129 and it
> forked another child process.  The documentation seems to imply that the
> 'open' takes place before traffic and before forking, which suggests to me
> that the connection is opened and remains open.  I'd prefer an arrangement
> where a connection was made each time a transaction sequence was initiated
> by traffic on the local, incoming, 3129 port (in my example), and then
> closed when traffic stopped.  I'll reread the documentation, anyway.

Well,wel,  aren't we a bit high maintenance? However I like how you ask
questions intelligently. IMO it's half the way to come to a solution. A
rare sight these days. With the fact that socat is pretty much the
universal patch cable, you are expecting too much here.
It seems you are looking for a protocol aware proxy. If you let us know
what protocol ...

Henning Follmann           | hfollmann@xxxxxxxxxxxxxxx