OK it was a layer 8 problem.
Instead of sending messages in udp I tested the connection with telnet which is tcp.
I sended some messages via socat and it worked well.
But somehow I can´t get messages from Barracuda.
In Firewall I opened all UDP ports but theres nothing arriving.
Could you please giva me a hint, how to get messages from Barracuda?
Here is my config:
