Stopping unauthorized queue managers sending messages to your queue manager
To prevent selected queue managers from sending messages to your queue manager, define a channel security exit program on the CLUSRCVR channel definition. Write a program that authenticates queue managers trying to send messages on your cluster-receiver channel and denies them access if they are not authorized. Channel security exit programs are called at MCA initiation and termination.
Clustering has no effect on the way security exits work. You can restrict access to a queue manager in the same way as you would in a distributed queuing environment.
By using SSL on your cluster--receiver channel you can force other queue managers in the cluster to authenticate themselves and keep out any that cannot.