Total Linux System z security starts with a secure network
Linux on System z employs some unique technologies that can potentially make delivering overall network security easier by providing centralized management capabilities and reducing the number of control checks -- device coupling controls, auditing and troubleshooting functions, and predefined network configurations (such as the HiperSockets adapters, technology that enables high-speed communications between partitions on a server with a hypervisor).
The IBM Redbooks tech note "Security for Linux on System z: Securing Your Network" offers a rather detailed abstract that explains these tools and how they work in order to set up a secure network, focusing on the task of configuring virtual switches to automatically manage which users can couple with them. An excellent read of a few minutes that can bring you a wealth of knowledge on secure networking.
To expand your Linux on System z security experience even further, you can tackle the complete Redbook publication this note was abstracted from: Security for Linux on System z. If you need more basic hands-on experience using Linux on System z (and cloud), take a look at the video IBM Linux on System z Cloud Test Drive to better understand virtualization, deployment, and image management from both a user and an administrator point of view.