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How to disable SELinux

By disabling SELinux you will be removing this security mechanism on your system. That might be a problem if  your system is on the Internet and accessed by the public. At the same time for internal system behind firewall SELinux is more troubles then it worth. It several interfere with functioning of many daemons and without good under sting of them troubleshooting became exceedingly difficult. Even is you want to preserve SElinux you should temporary disable it for the period of  troubleshooting problems to exclude one (and pretty complex) subsystem that can interfere with the applications you are having problems with.  

You can get the current status using the command

cat /selinux/enforce
If it is disabled then the result will be:
cat: /selinux/enforce: No such file or directory

You can either disable SELinux temporarily to test the problem, or permanently switch it off. It may also be a better option to make changes to the policy to permit the operations that are being blocked - but this requires knowledge of writing policies and may be a steep learning curve for some people. For the operating system as a whole, there is two kinds of disabling:

Disabling SELinux could lead to problems if you want to re-enable it again later. When the system runs with file labelling disable it will create files with no label - which could cause problems if the system is booted into Enforcement mode. A full re-labelling of the file system will be necessary.

Temporarily switch off enforcement

You can switch the system into permissive mode with the following command:
echo 0 >/selinux/enforce
You'll need to be logged in as root, and in the sysadm_r role:
newrole -r sysadm_r
To switch back into enforcing mode:
echo 1 >/selinux/enforce
In Fedora Core and RedHat Enterprise Linux you can use the setenforce command with a 0 or 1 option to set permissive or enforcing mode, its just a slightly easier command than the above.

To check what mode the system is in,

cat /selinux/enforce
If it is disabled then the result will be:
cat: /selinux/enforce: No such file or directory

which will print a "0" or "1" for permissive or enforcing - probably printed at the beginning of the line of the command prompt.

Permanently Permissive

The above will switch off enforcement temporarily - until you reboot the system. If you want the system to always start in permissive mode, then here is how you do it.

In Fedora Core and RedHat Enterprise, edit

/etc/selinux/config
and you will see some lines like this: :
# This file controls the state of SELinux on the system. 
# SELINUX= can take one of these three values: 
# enforcing - SELinux security policy is enforced. 
# permissive - SELinux prints warnings instead of enforcing. 
# disabled - No SELinux policy is loaded. SELINUX=enforcing 
# SELINUXTYPE= can take one of these two values: 
# targeted - Only targeted network daemons are protected. 
# strict - Full SELinux protection. SELINUXTYPE=targeted
... just change SELINUX=enforcing to SELINUX=permissive, and you're done. Reboot if you want to prove it.

For the other Linuxes which don't have the /etc/selinux/config file, you just need to edit the kernel boot line, usually in /boot/grub/grub.conf if you're using the GRUB boot loader. On the kernel line, add enforcing=0 at the end. For example,

title SE-Linux Test System root (hd0,0) 
kernel /boot/vmlinuz-2.4.20-selinux-2003040709 ro root=/dev/hda1 nousb enforcing=0 
initrd /boot/initrd-2.4.20-selinux-2003040709.img

Fully Disabling SELinux

Fully disabling SELinux goes one step further than just switching into permissive mode. Disabling will completely disable all SELinux functions including file and process labelling.

In Fedora Core and RedHat Enterprise, edit

/etc/selinux/config 
and change the SELINUX line to:
SELINUX=disabled
# This file controls the state of SELinux on the system. 
# SELINUX= can take one of these three values: 
# enforcing - SELinux security policy is enforced. 
# permissive - SELinux prints warnings instead of enforcing. 
# disabled - No SELinux policy is loaded. SELINUX=disabled 
# SELINUXTYPE= can take one of these two values: 
# targeted - Only targeted network daemons are protected. 
# strict - Full SELinux protection. SELINUXTYPE=targeted
... and then reboot the system.

For the other Linuxes which don't have the

/etc/selinux/config file, you just need to edit the kernel boot line, usually in /boot/grub/grub.conf, if you're using the GRUB boot loader. On the kernel line, add selinux=0 at the end. For example,
title SE-Linux Test System root (hd0,0) 
kernel /boot/vmlinuz-2.4.20-selinux-2003040709 ro root=/dev/hda1 nousb selinux=0 #initrd /boot/initrd-2.4.20-selinux-2003040709.img
You will have to reboot to disable SELinux, you just can't do it while the system is running.

Re-Enabling SELinux

If you've disabled SELinux as in the section above, and you want to enable it again then you've got a bit of work to do. The problem will be that files created or changed when SELinux was disabled won't have the correct file labels on them - if you just reboot in enforcing mode then a lot of stuff won't work properly.

What you need to do is to enable SELinux by editing /etc/selinux/config (for Fedora/RedHat) or by adding selinux=1 to the kernel boot line, then boot into permissive mode, then relabel everything, and then reboot into (or simply switch to) enforcing mode.

After booting into permissive mode, run fixfiles relabel

Alternatively, in Fedora and RedHat Enterprise Linux you can run touch /.autorelabel and reboot or put autorelabel on the boot command line -- in both cases the file system gets a full relabel early in the boot process. Note that this can take quite some time for systems with a large number of files.

After relabelling the filesystem, you can switch to enforcing mode (see above) and your system should be fully enforcing again.



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