...

<jgroups>
  <stack name="gossip-prod" extends="prod">
    <TCPGOSSIP initial_hosts="${jgroups.tunnel.gossip_router_hosts:localhost[12001]}"
             stack.combine="REPLACE" stack.position="MPING" />
    <FD_SOCK stack.combine="REMOVE"/>
    <VERIFY_SUSPECT timeout="2000"/>
    <SYM_ENCRYPT sym_algorithm="AES"
                 key_store_name="defaultStore.keystore"
                 store_password="changeit"
                 alias="myKey" stack.combine="INSERT_AFTER" stack.position="pbcast.NAKACK2" />
  </stack>
</jgroups>
 
...
