Support for "reverse connect" from IEC server?

[stenil31]

Hi!
I'm using your lib to implement a test server for our client implementation.
Now, in the production deployment, it is the IEC server that initiates the connection (TCP, and I think also on IEC104 level) to our client.
It seems this scenario is not supported by your library, any plans to implement this?
Thanks for a great library, it has helped us nicely sofar.
BR,
Stefan

[m-unkel]

Hi Stefan,

Thanks for reaching out, and we're really glad to hear the library has been helpful for your project so far!

You're right that the scenario where the IEC server initiates the connection isn't currently supported by the library.

tl;dr: At this time, we do not have plans to support this scenario.

Under the hood, our Python module relies on the lib60870-C implementation, which itself does not support a client-side listening socket. As far as we are aware, this behavior isn’t specified or mandated in the IEC 60870-5-104 standard, which generally defines the server (or "outstation") as the one accepting connections, and the client (or "control center") as the active initiator.

That said, if you have a use case where this connection flow is part of your production requirements, and if you know of any official guidance or exceptions in the standard that would allow (or require) this mode of operation, we’d be very interested to hear more. Also, pointers to implementations that support this mode would be welcome and helpful to the wider community.

Thanks again for your feedback!

[stenil31]

Hi,
thanks for your feedback.
I don't really know what the standard says about this, just that we need to handle this in our setup.
For our test purposes, we solved this by combining your library with a simple "TCP proxy" that is relaying data between our client component and your server.