As I said in a recent post, I don't think there is an easy way to run the firewall on a machine with multiple IOCs, since the subsequent IOCs need random ports to be opened for CA.
While thinking about your error message, I stumbled across this post to tech-talk from Dirk in 2019 . . .
Interesting idea. The IOC would need sufficient privileges to update the firewall rules. Curious if this is used in production.
This approach should be easier nowadays, as
Server exports RSRV_SERVER_PORT
During iocInit(), the environment variable RSRV_SERVER_PORT is set with the TCP port number selected.
starting from EPICS 7.0.7
Cheers,
~Ralph
