Configuring SELinux booleans
by Uday R. Sawant, William Leemans, Jonathan Hobson, Oliver Pelz
Linux: Powerful Server Administration
- Linux: Powerful Server Administration
- Table of Contents
- Linux: Powerful Server Administration
- Linux: Powerful Server Administration
- Credits
- Preface
- 1. Module 1
- 1. Managing Users and Groups
- 2. Networking
- Introduction
- Connecting to a network with a static IP
- Installing the DHCP server
- Installing the DNS server
- Hiding behind the proxy with squid
- Being on time with NTP
- Discussing load balancing with HAProxy
- Tuning the TCP stack
- Troubleshooting network connectivity
- Securing remote access with OpenVPN
- Securing a network with uncomplicated firewall
- Securing against brute force attacks
- Discussing Ubuntu security best practices
- 3. Working with Web Servers
- Introduction
- Installing and configuring the Apache web server
- Serving dynamic contents with PHP
- Hosting multiple websites with a virtual domain
- Securing web traffic with HTTPS
- Installing Nginx with PHP_FPM
- Setting Nginx as a reverse proxy
- Load balancing with Nginx
- Setting HTTPs on Nginx
- Benchmarking and performance tuning of Apache
- Securing the web server
- Troubleshooting the web server
- 4. Working with Mail Servers
- 5. Handling Databases
- Introduction
- Installing relational databases with MySQL
- Storing and retrieving data with MySQL
- Importing and exporting bulk data
- Adding users and assigning access rights
- Installing web access for MySQL
- Setting backups
- Optimizing MySQL performance – queries
- Optimizing MySQL performance – configuration
- Creating MySQL replicas for scaling and high availability
- Troubleshooting MySQL
- Installing MongoDB
- Storing and retrieving data with MongoDB
- 6. Network Storage
- 7. Cloud Computing
- 8. Working with Containers
- Introduction
- Installing LXD, the Linux container daemon
- Deploying your first container with LXD
- Managing LXD containers
- Managing LXD containers – advanced options
- Setting resource limits on LXD containers
- Networking with LXD
- Installing Docker
- Starting and managing Docker containers
- Creating images with a Dockerfile
- Understanding Docker volumes
- Deploying WordPress using a Docker network
- Monitoring Docker containers
- Securing Docker containers
- 9. Streaming with Ampache
- 10. Communication Server with XMPP
- 11. Git Hosting
- Introduction
- Installing Git
- Creating a local repository with Git CLI
- Storing file revisions with Git commit
- Synchronizing the repository with a remote server
- Receiving updates with Git pull
- Creating repository clones
- Installing GitLab, your own Git hosting
- Adding users to the GitLab server
- Creating a repository with GitLab
- Automating common tasks with Git hooks
- 12. Collaboration Tools
- 13. Performance Monitoring
- 14. Centralized Authentication Service
- 2. Module 2
- 1. Installing CentOS
- Introduction
- Downloading CentOS and confirming the checksum on Windows or OS X
- Creating USB installation media on Windows or OS X
- Performing an installation of CentOS using the graphical installer
- Running a netinstall over HTTP
- Installing CentOS 7 using a kickstart file
- Getting started and customising the boot loader
- Troubleshooting the system in rescue mode
- Updating the installation and enhancing the minimal install with additional administration and development tools
- 2. Configuring the System
- Introduction
- Navigating text files with less
- Introduction to Vim
- Speaking the right language
- Synchronizing the system clock with NTP and the chrony suite
- Setting your hostname and resolving the network
- Building a static network connection
- Becoming a superuser
- Customizing your system banners and messages
- Priming the kernel
- 3. Managing the System
- Introduction
- Knowing and managing your background services
- Troubleshooting background services
- Tracking system resources with journald
- Configuring journald to make it persistent
- Managing users and their groups
- Scheduling tasks with cron
- Synchronizing files and doing more with rsync
- Maintaining backups and taking snapshots
- Monitoring important server infrastructure
- Taking control with GIT and Subversion
- 4. Managing Packages with YUM
- 5. Administering the Filesystem
- 6. Providing Security
- 7. Building a Network
- 8. Working with FTP
- 9. Working with Domains
- 10. Working with Databases
- 11. Providing Mail Services
- 12. Providing Web Services
- 13. Operating System-Level Virtualization
- 14. Working with SELinux
- 15. Monitoring IT Infrastructure
- 1. Installing CentOS
- 3. Module 3
- 1. Working with KVM Guests
- 2. Deploying RHEL "En Masse"
- 3. Configuring Your Network
- 4. Configuring Your New System
- 5. Using SELinux
- 6. Orchestrating with Ansible
- 7. Puppet Configuration Management
- 8. Yum and Repositories
- 9. Securing RHEL 7
- 10. Monitoring and Performance Tuning
- Bibliography
- Index
SELinux booleans allow you to change the SELinux policy at runtime without the need to write additional policies. This allows you to change the policy without the need for recompilation, such as allowing services to access NFS volumes.
This is the way to temporarily or permanently change SELinux booleans.
For a list of all booleans and an explanation of what they do, execute the following:
~# semanage boolean -l
Now, let's try to get the value of a particular SELinux boolean. It is possible to get the value of a single SELinux boolean without the use of additional utilities, such as grep and/or awk. Simply execute the following:
~# getsebool <SELinux boolean>
This shows you whether or not the boolean is set. Here's an example:
~# getsebool virt_use_nfs virt_use_nfs --> off ~#
To set a boolean value to a particular one, use the following command:
~# setsebool <SELinux boolean> <on|off>
Here's an example command:
~# setsebool virt_use_nfs on
This command allows you to change the value of the boolean, but it is not persistent across reboots. To allow persistence, add the -P option to the command line, as follows:
~# setsebool -P virt_use_nfs on
If you would like a list of all the bare bones of SELinux booleans and their values, getsebool -a is an alternative, as follows:
~# getsebool -a
Managing SELinux booleans can be rather complex as there are a lot of booleans, and their names are not always simple to remember. For this reason, the setsebool, getsebool, and semanage tools come with tab completion. So, whenever you type any boolean name, you can use the tab key to complete or display the possible options.
Here's an example of an AVC denial report found in the audit.log file that can be solved by enabling a boolean:
type=AVC msg=audit(1438884483.053:48): avc: denied { open } for pid=1270 comm="httpd" path="/nfs/www/html/index.html" dev="0:38" ino=2717909250 scontext=system_u:system_r:httpd_t:s0 tcontext=system_u:object_r:nfs_t:s0 tclass=fileThis is an example of a service (httpd in this case) accessing a file located on an NFS share, which is disabled by default.
This can be allowed by setting the httpd_use_nfs boolean to "on".
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