When running a front end Web Agent Reverse Proxy, the back-end server doesn't run a Web Agent and as such internal people can reach directly the application without being challenged for credentials.
How to protect the back-end server from direct access?
Install a Web Agent on the back-end server application, It would rather request the Policy Server to check the validity of the session data.
If the browser doesn't present an SMSESSION cookie, it will challenge the user for credentials.
So having a Web Agent running on the back-end server application will allow you protection in a much finer way the direct accesses to the back-end server.
SiteMinder provides many flavors of Agents:
SiteMinder Web Server Agents SiteMinder Agents for WebSphere SiteMinder Agents for WebLogic SiteMinder Agent for JBoss SiteMinder SharePoint Agent SiteMinder Siebel Agent SiteMinder SAP WebAS Agent SiteMinder PeopleSoft Agent SiteMinder Web Services Security Agents SiteMinder SDK
among the others (1).
There's no specific Agent to run in an OpenShift environment (2).