IB 6.01 on Linux 2.18, D4 IBO 3.6ca

IB comunicates via port 3050.

IB works fine through a firewall that has 3050 open. But then, when
the 'RegisterEvents' method gets called nothing goes anymore.

A tcpdump reveals that IB obviously tries to open another ip
connection for event messaging which is different than 3050. E.g. I
found ports 178x being used counting up with every 'RegisterEvent'
call.

Does anyone know which range of ports need to be accessible for IB in
order make use of events in a restricted network setup?

There are NO problems at all in a non-restricted network scenario!

Cheers

Johannes