On some of the Linux distribution SELinux is enabled by default, which may cause some unwanted issues, if you don’t understand how SELinux works and the fundamental details on how to configure it. I strongly recommend that you understand SELinux and implement it on your environment. But, until you understand the implementation details of SELinux you may want to disable it to avoid some unnecessary issues.
To disable SELinux you can use any one of the 4 different methods mentioned in this article.
The SELinux will enforce security policies including the mandatory access controls defined by the US Department of Defence using the Linux Security Module (LSM) defined in the Linux Kernel. Every files and process in the system will be tagged with specific labels that will be used by the SELinux. You can use ls -Z and view those labels as shown below.
# ls -Z /etc/ -rw-r--r-- root root system_u:object_r:etc_t:s0 a2ps.cfg -rw-r--r-- root root system_u:object_r:adjtime_t:s0 adjtime -rw-r--r-- root root system_u:object_r:etc_aliases_t:s0 aliases drwxr-x--- root root system_u:object_r:auditd_etc_t:s0 audit drwxr-xr-x root root system_u:object_r:etc_runtime_t:s0 blkid drwxr-xr-x root root system_u:object_r:bluetooth_conf_t:s0 bluetooth drwx------ root root system_u:object_r:system_cron_spool_t:s0 cron.d -rw-rw-r-- root disk system_u:object_r:amanda_dumpdates_t:s0 dumpdates
Method 1: Disable SELinux Temporarily
To disable SELinux temporarily you have to modify the /selinux/enforce file as shown below. Please note that this setting will be gone after the reboot of the system.
# cat /selinux/enforce 1 # echo 0 > /selinux/enforce # cat /selinux/enforce 0
You can also use setenforce command as shown below to disable SELinux. Possible parameters to setenforce commands are: Enforcing , Permissive, 1 (enable) or 0 (disable).
# setenforce 0
Method 2: Disable SELinux Permanently
To disable the SELinux permanently, modify the /etc/selinux/config and set the SELINUX=disabled as shown below. One you make any changes to the /etc/selinux/config, reboot the server for the changes to be considered.
# cat /etc/selinux/config SELINUX=disabled SELINUXTYPE=targeted SETLOCALDEFS=0
Following are the possible values for the SELINUX variable in the /etc/selinux/config file
- enforcing – The Security Policy is always Encoforced
- permissive – This just simulates the enforcing policy by only printing warning messages and not really enforcing the SELinux. This is good to first see how SELinux works and later figure out what policies should be enforced.
- disabled – Completely disable SELinux
Following are the possible values for SELINUXTYPE variable in the /etc/selinux/config file. This indicates the type of policies that can be used for the SELinux.
- targeted – This policy will protected only specific targeted network daemons.
- strict – This is for maximum SELinux protection.
Method 3: Disable SELinux from the Grub Boot Loader
If you can’t locate /etc/selinux/config file on your system, you can pass disable SELinux by passing it as parameter to the Grub Boot Loader as shown below.
# cat /boot/grub/grub.conf default=0 timeout=5 splashimage=(hd0,0)/boot/grub/splash.xpm.gz hiddenmenu title Enterprise Linux Enterprise Linux Server (2.6.18-92.el5PAE) root (hd0,0) kernel /boot/vmlinuz-2.6.18-92.el5PAE ro root=LABEL=/ rhgb quiet selinux=0 initrd /boot/initrd-2.6.18-92.el5PAE.img title Enterprise Linux Enterprise Linux Server (2.6.18-92.el5) root (hd0,0) kernel /boot/vmlinuz-2.6.18-92.el5 ro root=LABEL=/ rhgb quiet selinux=0 initrd /boot/initrd-2.6.18-92.el5.img
Method 4: Disable Only a Specific Service in SELinux – HTTP/Apache
If you are not interested in disability the whole SELinux, you can also disable SELinux only for a specific service. For example, do disable SELinux for HTTP/Apache service, modify the httpd_disable_trans variable in the /etc/selinux/targeted/booleans file.
Set the httpd_disable_trans variable to 1 as shown below.
# grep httpd /etc/selinux/targeted/booleans httpd_builtin_scripting=1 httpd_disable_trans=1 httpd_enable_cgi=1 httpd_enable_homedirs=1 httpd_ssi_exec=1 httpd_tty_comm=0 httpd_unified=1
Set SELinux boolean value using setsebool command as shown below. Make sure to restart the HTTP service after this change.
# setsebool httpd_disable_trans 1 # service httpd restart
Comments on this entry are closed.
Thanks… I’ve been using Ubuntu, which is better, SELinux or AppArmor?
Both SELinux and AppArmos has it’s own advantages. Please refer to this comparison article that talks about SELinux vs AppArmor
thank you very much for this book
this book i very use full for me
this was very useful to understand selinux concept in brief.
I have problems with setsebool
"Could not change active booleans: Invalid boolean"
echo 0 > /selinux/enforce
actually switch SELinux to permissive mode.
check output of two following commands (RHEL/CentOS):
1) selinuxenabled | echo $? # 0 means selinux enabled, 1 – disabled
2) getenforce # will print one of Disabled|Enforcing|Permissive
check ‘man setenforce’
this command will not disable SELinux, but switches it to permissive mode
Verified easily by selinuxenabled & getenforce
So, please let me know if you will find a way do disable SELinux without reboot.
Please explain SELinux in detail.
Thank you. Now my doubt is cleared. 🙂
This is a little out of date. /selinux/ doesn’t exist on most Fedora/RHEL based systems of today
this guide is only for RHEL, not linux….
great article. Selinux is extremely annoying. Should be permanently disabled by default.