WebLogic: The Definitive Guide

Securing a Clustered Solution

When you design the physical architecture for your enterprise application using clusters of WebLogic instances, you need to determine which resources are directly exposed to external clients, and which resources need not be on the front line but instead require extra defenses. This means you need to outline a demilitarized zone (DMZ), a conceptual area of hardware and software resources that is directly exposed to the outside world. All resources that live behind the DMZ are protected. A DMZ is often created by employing a firewall, which can deny access to specific ports and IP addresses (and hence physical machines) participating in a WebLogic domain. The firewall lets you clearly define which services on which machines ought to be accessible to external clients. Generally, the smaller the extent of your DMZ, the safer your architecture is from malicious attacks.

Your application setup also impacts the scope of your DMZ. For instance, if you adopt the combined-tier architecture as illustrated earlier in Figure 14-6, you are forced to include all of the servers in the DMZ, even though you may wish to grant clients direct access only to the servlets, JSPs, and static web resources, and not to the EJBs and RMI objects deployed to the cluster. Instead, if you adopt the more complex multi-tier application setup, you have the option of physically denying access to the object tier machines, thereby excluding them from the DMZ.

Firewalls can provide network ...