Book Image

SELinux System Administration, Third Edition - Third Edition

By : Sven Vermeulen
Book Image

SELinux System Administration, Third Edition - Third Edition

By: Sven Vermeulen

Overview of this book

Linux is a dominant player in many organizations and in the cloud. Securing the Linux environment is extremely important for any organization, and Security-Enhanced Linux (SELinux) acts as an additional layer to Linux system security. SELinux System Administration covers basic SELinux concepts and shows you how to enhance Linux system protection measures. You will get to grips with SELinux and understand how it is integrated. As you progress, you’ll get hands-on experience of tuning and configuring SELinux and integrating it into day-to-day administration tasks such as user management, network management, and application maintenance. Platforms such as Kubernetes, system services like systemd, and virtualization solutions like libvirt and Xen, all of which offer SELinux-specific controls, will be explained effectively so that you understand how to apply and configure SELinux within these applications. If applications do not exert the expected behavior, you’ll learn how to fine-tune policies to securely host these applications. In case no policies exist, the book will guide you through developing custom policies on your own. By the end of this Linux book, you’ll be able to harden any Linux system using SELinux to suit your needs and fine-tune existing policies and develop custom ones to protect any app and service running on your Linux systems.
Table of Contents (22 chapters)
1
Section 1: Using SELinux
8
Section 2: SELinux-Aware Platforms
14
Section 3: Policy Management

Chapter 5

  1. The command to apply a type to a TCP port is created with semanage. For instance, to apply the ssh_port_t type to TCP port 10122, execute the following command:
    # semanage port -a -t ssh_port_t -p tcp 10122

    However, this only works as long as the port itself is not already explicitly mapped to an SELinux type. You can query whether this is the case with sepolicy, for example:

    # sepolicy network -p 10122

    If the port is part of an unreserved range, then it can be altered.

  2. No, SECMARK is local to the system. Once a network packet is received by the Linux host, the SECMARK rules will associate a label with that network packet, but this label is only retained in memory on the system itself. Once a packet leaves the Linux system, it will not show any trace of SECMARK labeling.
  3. The subcommands used by semanage are ibendport (to apply a label or sensitivity to an InfiniBand network port) and ibpkey (to apply a label or sensitivity to a partition key).
  4. While labeled IPsec...