Reset Root Centos 6.10 How To Lock User

It is recommended that one should enable login or ssh attempts policy, means users account should be locked automatically after n numbers of failed (or incorrect) login or ssh attempts.

In Linux distribution like CentOS, RHEL and Fedora this is achieved by using pam module pamfaillock and for Debian like distributions, this can be achieved using pamtally2 pam module.

Reset Root Centos 6.10 How To Lock User

In this tutorial we will learn how to lock user accounts after n failed login attempts in CentOS, RHEL, Fedora, Debian Ubuntu For CentOS RHEL Fedora Add the following lines in two files etcpam.dpassword-auth etcpam.dsystem-auth, auth required pamfaillock.so preauth silent audit deny3 unlocktime600.

Example is demonstrated below where these lines needs to be added, email protected vi etcpam.dpassword-auth email protected vi etcpam.dsystem-auth After making changes in both the files, restart the ssh service using below systemctl command, email protected systemctl restart sshd Lets do the testing whether user account will be locked after three unsuccessful login attempts or not.

Lets assume we have a local account with name pkumar, we will try to ssh our Linux system with this account with incorrect passwords, ssh email protected.

Now view auth log file to see whether incorrect login attempts are captured or not, email protected: tail varlogauth.log Above logs confirms that account has been locked, lets verify from pamtally2 command, email protected: sudo pamtally2 -u devops.

Read Also: How to Enforce Password Policies in Linux (Ubuntu CentOS) Facebook.

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The process has changed from CentOSRHEL (Red Hat Enterprise Linux) version 6 to 7, as previously you would boot into single user mode and then change the password as root.

From version 7 the equivalent modes are the rescue or emergency targets, however these require the root password before you can do anything which doesnt help us here, so well take you through the new process to change the lost root password.

This is also a task that you will need to know how to perform for the RHCSA exam.

As with all system maintenance tasks, be sure you have a system backupsnapshot prior to proceeding.

At the boot menu, press the e key to edit the first boot entry.

This is required so that any further commands we run will be in regards to sysroot.

This is because when the passwd command is run, it creates a new etcshadow file.

As SELinux is not running in this mode the file is created with no SELinux contexts, which can cause problems when we reboot.

Creating this file will automatically perform a relabel of all files on next boot.

Note that this may take some time depending on the amount of files you have on the file system.

Summary As shown we can reset the root password in Linux CentOSRHEL 7 by booting with the rd.break option, remounting the file system with readwrite privileges, creating a chroot jail, executing the passwd command and then finally fixing up SELinux contexts.

After exiting the chroot and the initramfs root shell prompt the file system will be relabelled which may take a few minutes or more depending on the number of files you have.

When your system has booted back up youll be able to use the new root password.

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After I pressed ctrld 2 times post changing the paddword, the screen gets stuck, probably it is due to the mass relabelling as mentioned in the explanation above.

I tried with different servers and still encounter same issue.

Fortunately I found another option how to jump into single mode.

Clean and Crisp. Worked perfectly for RHEL-7 server installed as VM.

By default it should only be available to the root user, so keep users with root privileges secure and set strong passwords so that if the hash is discovered it becomes infeasible to attack.

Solution was to mount proc first ( ): mount proc proc And then procceed with pass change: passwd.

Reset Root Password Centos 6.10