User Permissions for Oracle RAC

When you upgrade to 4.3, you may encounter the following error: Network access denied by access control list (ACL).

You can resolve the error by enabling ACLs for the monitoring user.
CODE 
begin
dbms_network_acl_admin.create_acl (
acl             => 'Resolve_Access.xml',      
description     => 'Resolve Network Access using UTL_INADDR', 
principal       => '<DBMON USER>',                                                    
is_grant        => TRUE,                     
privilege       => 'resolve',                
start_date      => null,                     
end_date        => null                      
);
commit;
end;
/

begin
dbms_network_acl_admin.assign_acl (
acl           => 'Resolve_Access.xml',
host          => '*',                                                   
lower_port    => null,                
upper_port    => null);               
commit;
end;
/