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--- werkinstructies:recover_root_password [2016/03/26 14:56]
abel
+++ werkinstructies:recover_root_password [2018/08/30 08:59] (huidige)
abel
@@ Regel 1: / Regel 1: @@
 ====== Root password recovery on console of CentOS7 ======
-there are times you may need to reset the root password which is unknown to you.
+There are times you may need to reset the root password which is unknown to you.
 This procedure will work fast on systems that have SELinux enabled and large volumes with lots of files which you definitely do not want to relabel as it is timeconsuming resulting in long down time.
-So, get on to the console, reboot the server and interupt the bootproces by pressing the up arrow button, and you get a list of boot profiles not unlike:
+  * Get on to the console, reboot the server and interupt the bootproces by pressing the up arrow button and you get a list of boot profiles not unlike:<code>
-<code>
 CentOS Linux (3.10.0-327.10.1.el7.x86_64) 7 (Core)
 CentOS Linux (3.10.0-327.3.1.el7.x86_64) 7 (Core)
@@ Regel 14: / Regel 13: @@
 </code>
-from the list of boot profiles chose the last and pres ''e'' to edit the boot profile.
+  * From the list of boot profiles chose the latest, which is at the top, and pres ''e'' to edit the boot profile.
-find the line that starts with ''linux16 /vmlinuz-3.10......''
+  * Find the line that starts with ''linux16''. In our case:<code>
+linux16 /vmlinuz-3.10.1.0-327.10.1.el7.x86_64 root=/dev/mapper/centos-root
+ro rd.lvm.lv=centos/swap vconsole.font=tatarcyrheb-sun16 rd.lvm.lv=centos/root
+craskkernel=auto  vconsole.keymap=us rhgb quiet LANG=en_US.utf8
+</code>
-replace ''ro'' with ''rw'' and aad to the end of that line: ''rd.break enforce=0''
+  * Replace ''ro'' with ''rw'' and add to the end of that line: ''rd.break enforce=0''<code>
+linux16 /vmlinuz-3.10.1.0-327.10.1.el7.x86_64 root=/dev/mapper/centos-root
+rw rd.lvm.lv=centos/swap vconsole.font=tatarcyrheb-sun16 rd.lvm.lv=centos/root
+craskkernel=auto  vconsole.keymap=us rhgb quiet LANG=en_US.utf8 rd.break enforce=0
+</code>
+  * Now press ''Ctrl x''
-now press ''Ctrl x''
+<note tip> you could remove ''rhgb quiet'' to get more info on the boot proces in case of trouble.</note>
-the system boots and presents you with a prompt: ''switch_root:/# _''
+The system boots and presents you with a prompt: ''switch_root:/# _''. We need to chroot to the filesystem on which the ''/etc/shadow'' file is present.
-We need to chroot to the filesystem on which the /etc/shadow file is present, do so by: ''chroot /sysroot'' your prompt changes to ''sh-4.2# _''
+  * Do so by: ''chroot /sysroot'' your prompt changes to ''sh-4.2# _''
-Change the root password ''passwd root'' and enter your new password.
+  * Change the root password ''passwd root'' and enter your new password.
-now we need to continue the boot proces, do so by exiting the chroot shell ''exit'' and then the rescue shell ''exit'' .
+Now we need to continue the boot proces.
-The boot process continues and you are presented by the regular login prompt.
+  * Do so by exiting the chroot shell ''exit'' and then the rescue shell ''exit''.
+The boot process continues and you are presented by the regular login prompt.\\
 However, we forced the system to boot in SELinux permissive mode because we needed to alter the shadow password file. We need to correct this:
-First restore the SELinux context of the shadow password file: ''restorecon /etc/shadow''
+  * Log in (with your new password)
+  * Restore the SELinux context of the shadow password file: ''restorecon /etc/shadow''
-Second set SELinux to enforcing again : ''setenforce 1''
+  * Set SELinux to enforcing again : ''setenforce 1''
+Done.

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