RHEL family tutorials - Page 3

Add a user to a supplementary group in Linux with usermod -aG, gpasswd -a, or adduser on Debian. Verify with id, apply changes with newgrp or re-login, and avoid the missing -a mistake.

Configure BIND primary and secondary DNS on RHEL-family Linux with allow-transfer, slave zones, named-chroot on Rocky Linux 8, and dig verification after AXFR zone replication.

Learn how to exclude selected users from pam_faillock account lockout on RHEL, Rocky Linux, AlmaLinux, and Oracle Linux using authselect and PAM rules.

Step by step guide to build ceph storage cluster in Openstack CentOS 7 Linux on virtual machine. Confiure OSD, mon using ceph-deploy tool for ceph cluster

Understand kernel-core on RHEL, the difference between kernel, kernel-modules-core and kernel-modules, which packages you need, and how DNF updates them safely.

Update the kernel safely on RHEL with DNF. Check available versions, install the latest kernel, verify the default boot entry, reboot, and confirm the new kernel.

Learn RHEL patch management with DNF: identify security advisories and CVEs, apply security-only updates, patch specific RHSA or CVEs, and verify remediation.

Fix "There are no enabled repositories" on RHEL by checking DNF repositories, system registration, BaseOS/AppStream, Subscription Manager, and offline repository configuration.

Remove old Linux kernels safely on RHEL, Rocky Linux and AlmaLinux with dnf remove --oldinstallonly, protecting the running kernel and a bootable fallback.

Downgrade an installed RPM package on RHEL-family systems with dnf downgrade, install an exact older build, handle common errors, and lock the version with versionlock.

Rebuild the initramfs image with dracut for one kernel or every installed kernel, add storage and network drivers, and inspect the result with lsinitrd.

Get RHEL at no cost with the Red Hat Developer Subscription for Individuals: create an account, activate the subscription, pick the Boot or DVD ISO, and verify the download.

Register RHEL with subscription-manager, verify Simple Content Access, enable BaseOS and AppStream repositories, configure a proxy, and unregister.

Reset a forgotten root password on RHEL 10 from the GRUB menu with rd.break, remount /sysroot, chroot, passwd, and SELinux autorelabel before you log in again.

Manage Linux users and groups with useradd, usermod, userdel, groupadd, primary and supplementary groups, account defaults, and ownership checks.

Configure Chrony NTP on Linux, verify time synchronization with chronyc, force clock correction, troubleshoot sync problems, and optionally serve LAN clients.

Learn the Linux boot process from UEFI or BIOS through GRUB, the kernel, initramfs, and systemd, with inspection commands and troubleshooting.

Create coordinated LVM snapshot sets with snapm, boot into a snapshot through Boom and GRUB, inspect an earlier system state, revert failed changes, monitor snapshot capacity, and delete snapshot sets on Rocky Linux …

Convert an existing dhcpd.conf to Kea JSON with KeaMA, correct unsupported directives, test reservations and leases on an isolated lab, compare DHCP offers, and cut over from ISC DHCP to Kea with a tested rollback path.

Install and configure the Kea DHCPv4 server on Rocky Linux 10, RHEL 10, or AlmaLinux 10 with a JSON address pool, gateway and DNS options, MAC reservation, and lease verification on an isolated lab network.

Use perf stat, perf record, and perf report on Linux to find CPU bottlenecks, collect call graphs, and resolve symbols with debuginfod on Rocky Linux, RHEL, Debian, Ubuntu, and other distributions.

Install Nginx, MariaDB, PHP, and PHP-FPM on Rocky Linux, RHEL, AlmaLinux, or Oracle Linux, then verify the complete LEMP stack with a PHP database test.

Install Apache, MariaDB, PHP, and PHP-FPM on Rocky Linux, RHEL, AlmaLinux, or Oracle Linux, then verify the complete LAMP stack with a PHP database test.

Install PHP 8.4 from native AppStream php8.4-* packages on RHEL 10.2+, Rocky Linux, AlmaLinux, Oracle Linux, or CentOS Stream 10 when dnf info php8.4 confirms availability, then configure php-fpm and verify Apache or …

Replace native PHP 8.3 packages with php8.4-* RPMs on EL 10, back up configuration, check application compatibility, migrate PHP-FPM settings, verify web applications, troubleshoot failures, and roll back if required.

Install and configure BIND on RHEL, Rocky Linux, or AlmaLinux with forward and reverse zones, controlled recursion, NetworkManager clients, and dig testing.

Install PostgreSQL 18 on RHEL, Rocky Linux, AlmaLinux, Oracle Linux, or CentOS Stream using native packages or PGDG, then initialize and verify the server.

Migrate legacy network-scripts and ifcfg profiles to NetworkManager keyfiles on RHEL, Rocky Linux, AlmaLinux, Oracle Linux, and CentOS Stream before upgrading to a release that no longer reads ifcfg files.

Learn how to check ML-KEM support in TLS, create ML-DSA signatures, and verify post-quantum SSH key exchange on Linux, with tested Rocky Linux examples.

Enable DNS over TLS on RHEL 10.1 or later with NetworkManager, dnsconfd, and unbound, then verify upstream DNS uses encrypted TCP port 853.