Sunday, June 10, 2012

Disable SeLinux

This always seems to bit me in the ass, so here's some simple instructions on disabling SeLinux.

(ganked from: )

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

# echo 0 > /selinux/enforce

# cat /selinux/enforce
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
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
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 thehttpd_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
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

So you want a fresh Ubu install and don't want to hunt-down all you currently packages....

..and reinstall them all one-by-one or write a silly script to handle them all. Well, here's a simple solution: 

Save currently installed packages:
 # dpkg --get-selections > packages.installed 

Save this off and then copy to new machine or back to re-installed, then do:

 # dpkg --set-selections < packages.installed
(* Note: You may want to prune the list of software that you don't want to install or is incompatible if newer version of OS, before doing import above.)

 Then do: # dselect

Also, don't forget to save and copy over your /etc/apt/sources.list of course.

 That's it! Simple, eh?