erlang nodes interop.

[Sverker Eriksson]

Hi Bogdan

I have tried to reproduce, but I succeed to connection from OTP 24.1.4 to both 19.0 and 19.3.6.13. Tested on both same host and between hosts.

I'm not sure that it matters, but what version of the epmd daemon process is running on the 19-host?

/Sverker @ Erlang/OTP
________________________________
From: erlang-questions <erlang-questions-bounces@REDACTED> on behalf of Bogdan Andu <bog495@REDACTED>
Sent: Thursday, November 11, 2021 11:46 AM
To: Erlang <erlang-questions@REDACTED>
Subject: erlang nodes interop.

Hi,

I have two erlang nodes, NodeA and NodeB.
NodeA is OTP version 19 and NodeB is OTP version 24.1.4.

The nodes have the same cookie;
and they are both started as sname nodes.

However, the following happens:
Connecting from NodeB to NodeA always fails.
(Node@REDACTED)1> net_kernel:connect_node('Node@REDACTED').
(Node@REDACTED)2> false

Eleven if I
Until:
Connecting from NodeA to NodeB always succeeds:
(Node@REDACTED)1> net_kernel:connect_node('Node@REDACTED').
(Node@REDACTED)2> true

After that, connecting from NodeB to NodeA succeeds:
(Node@REDACTED)1> net_kernel:connect_node('Node@REDACTED').
(Node@REDACTED)2> true

The same behaviour with net_adm:ping/1 or erlang:set_cookie(/2

A version 19 erlang node is needed because interoperability with
legacy internal ssl systems andalso other systems in production
depend on OTP 19.

An OTP  19 node is old enough to support older ssl protocols and
new enough to NOT generate the following error in an otp 24 node:
rejected since it cannot handle ["BIG_CREATION"]

I need connection from NodeA to NodeB to always succeed
because NodeB is the initiating(client) to NodeA, and
NodeA is a RPC server for NodeB.

What can be done?

Thank you,

Bogdan
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