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Re: TCP proxy for host on subnet




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

socat -d -d -lmlocal2 \
TCP4-LISTEN:3129,su=nobody,fork,range=192.168.0.0/24,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.

May I, in passing, note that Darac was kind enough to say, On 05/06/2017 14:21:

>
> Depending on the protocol, might something like nginx work? It's
> perhaps using a sledgehammer to crack a nut, but it does include
> the ability to proxy arbitrary tcp and udp connections and forward
> them on to one or more "back-end" hosts.
>

Darac, that was an interesting option. Though the learning curve makes it difficult to quickly implement this to solve the specific problem I have, using nginx would also help me with a different information presentation problem to solve, by deploying a web server to present quite a lot of static information in an accessible form for client machines that use http.

I hadn't realised that nginx can be configured this way, and I'll consider using this mode as well as the http service that I do/will need on this LAN segment.

regards, Ron