SELinux for Beginners using CentOS

1. Does CentOS use SELinux?
2. How do I get SELinux version?
3. Is SELinux worth the trouble?
4. How does SELinux work?
5. How do I know if SELinux is enforcing?
6. Why do we disable SELinux?
7. Is SELinux enabled by default?
8. What happens if SELinux is disabled?
9. What is SELinux permissive mode?
10. Is SELinux permissive dangerous?
11. Is permissive SELinux bad?
12. Is it dangerous to disable SELinux?

Does CentOS use SELinux?

Linux distributions such as CentOS, RHEL, and Fedora are equipped with SELinux by default. SELinux improves server security by restricting and defining how a server processes requests and users interact with sockets, network ports, and essential directories.

How do I get SELinux version?

The easiest way on how to check SELinux ( Security Enhanced Linux ) operation mode is to use getenforce command. This command without any options or arguments will simply print a current status SELinux operational mode. Furthermore, the current status of SELinux operational mode can be set permanently or temporarily.

Is SELinux worth the trouble?

SELinux places new constraints on how files are accessed on Linux systems. As a new security mechanism, it's a lot to absorb and it adds a good deal of complexity to our systems. Even so, the security that it provides above and beyond what's been available in the past makes it well worth learning and using.

How does SELinux work?

How does SELinux work? SELinux defines access controls for the applications, processes, and files on a system. ... When an application or process, known as a subject, makes a request to access an object, like a file, SELinux checks with an access vector cache (AVC), where permissions are cached for subjects and objects.

How do I know if SELinux is enforcing?

Following are three different ways to check the status of SELinux:

1. Use the getenforce command. [vagrant@vagrantdev ~]$ getenforce Permissive.
2. Use the sestatus command. ...
3. Use the SELinux Configuration File i.e. cat /etc/selinux/config to view the status.

Why do we disable SELinux?

One common reason to disable the firewall is, as we know HDFS maintains replication in different nodes/racks but it shouldn't take any extra time for that. Setting firewall using SElinux may disturb this (or) lead to performance issue. So the general recommendation is to disable the firewall.

Is SELinux enabled by default?

SELinux is installed and enabled by default, and for most users it will function without issue affording an enhanced level of security.

What happens if SELinux is disabled?

And yes, disabling security features—like turning off SELinux—will allow software to run. ... For those who don't use Linux, SELinux is a security enhancement to it that supports mandatory access controls. SELinux support can take the form of any number of Linux distributions, like Red Hat Enterprise Linux (RHEL).

What is SELinux permissive mode?

Permissive Mode. When SELinux is running in permissive mode, SELinux policy is not enforced. The system remains operational and SELinux does not deny any operations but only logs AVC messages, which can be then used for troubleshooting, debugging, and SELinux policy improvements.

Is SELinux permissive dangerous?

That's why the first versions of Android shipping SELinux included it in "Permissive" mode by default. ... At this point, SELinux can be turned into "Enforcing" mode: it will now not only log but also block every offending action.

Is permissive SELinux bad?

It isn't really fine on Linux desktops either. SELinux is a really powerful tool to to increase security of your machine. Putting it into permissive is a really bad and lazy approach to ignore your problems. It's like using a single password for all websites.

Is it dangerous to disable SELinux?

Simply put, disabling mandatory access control(MAC) mechanisms like SELinux is not a good idea and may put you at a security-disadvantage if a bad guy successfully circumvent name-based access controls, implemented by Discretionary Access Control(DAC).