Red Hat System Administration and Troubleshooting - RHCSA

Explore how an enterprise obtains Red Hat portal access, secures a ten-server subscription, and admins create domain users to manage accounts, downloads, and support cases.

Explore the Red Hat portal with a focus on subscription management, entitlement, login, user management, and support cases, plus an overview of downloads, contracts, and OpenShift.

Understand how Red Hat subscription and entitlement work, including how a single subscription yields two entitlements for physical servers and one entitlement per virtual machine, with examples.

Learn why you should never use auto attach for Red Hat subscriptions, and how to manage licenses by contract owners to avoid cross-team conflicts, with standard versus premium support implications.

Log in to the Red Hat customer portal, manage users, invite new teammates, and download the latest Red Hat Enterprise Linux (9.2) for offline installation.

Install Red Hat Enterprise Linux 9.2 in VirtualBox, allocate 32 GB RAM and 50 GB storage, enable bridged networking, and set root password before creating a new user for ssh.

Explore why red hat suits production with subscription and support, while centos fits testing with free repositories, using bank scenarios to show patching and potential downtime.

Understand online and offline infrastructure for Red Hat updates, including subscriptions via the portal and offline satellite capsule models for secure, automated patching.

Learn how to register a Red Hat server, attach subscriptions and licenses, and manage online versus offline registration to enable yum repositories and Red Hat support.

Learn to register a Red Hat server offline by attaching a subscription, importing the certificate, and linking the system to Red Hat without internet access.

Learn how to raise a Red Hat support case after subscribing. Understand standard versus premium support, set urgency, and upload source or sos reports.

Learn to transfer files between Windows and Linux/Unix using Filezilla or SCP; perform upload and download, manage destination paths, and understand ownership and permissions with FTP, SFTP, and SCP.

Explore shell terminals, focusing on Bash as the most widely used shell for system administration, with comparisons to other shells and practical tips on using autocomplete and switching shells.

Navigate the Linux file system starting at the root slash, learn absolute paths, common directories like /home and /tmp, and how mounts affect the root.

Master the pipeline concept by chaining commands to filter and refine command-line outputs with pipes, on Linux, Unix, Mac, and Windows.

Learn the essential command used daily across Linux, Unix, and Mac for system administration; master common options and flags, and apply daily checks, disk, network, and patching tasks.

Explore essential Linux commands with the man command for quick help, and learn ls usage with -l, -a, -h to list files, including hidden ones, with sizes and sort options.

Navigate linux directories with cd and pwd to verify location. Master core file operations with cp, mv, rm, mkdir, touch, and ls -l, while noting permissions and root access.

Master grep to search logs and files quickly. Use flags -i, -r, -l, -n, -w, -A/-B, and -v.

Master essential linux commands for disk and file tasks. Use df -h for human readable sizes, cat and grep for searching, tail -f for logs, and aliases to save time.

Learn to edit Linux files using Vim and nano, mastering insert mode, saving, quitting, and basic navigation with arrow keys, search, and simple copy-paste.

Master redirection operators to pipe command output into files, append or overwrite data, and redirect errors to files or dev/null, enabling clean reports and automated shell scripts.

Explore linux permissions with ls -l outputs, identifying owner, group, size, date, and the three permission triplets for user, group, and others; learn file, directory, and simple link types.

Explore how Linux file permissions work, understand the user, group, and others rwx trio, and change permissions with symbolic and numeric methods to strengthen security.

Learn how to interpret permissions using read, write, and execute mapped to user, group, and others, with examples like 644, 755, and 777, and the dangers of recursive chmod -R.

Learn to change file ownership and group with chown, and modify permissions with chmod, including recursive application with -R, while recognizing root is the superuser.

Learn to manage running processes using ps, top, and kill commands; locate PIDs, terminate unresponsive processes, and monitor server activity with systemctl and top.

Learn unix permissions and group-based access to manage directory access, add or remove users, streamline system administration, and apply permissions through groups across all directories.

Learn to create users and groups with explicit uid and gid, set primary and secondary groups, and delete users with or without their home directories.

The lecture explains how to use the su command to switch to root or other users, shows root can switch without a password, and covers dash vs no-dash directory behavior.

Learn how sudo delegates root privileges via sudoers rules, manages user and group permissions, logs actions in var logs, and safely switch to root with sudo -i or sudo su.

Learn to manage linux services with systemctl: start, stop, restart, reload, enable, and disable; view status and unit files, and explore configuring ssh, httpd, and firewall basics.

Create a custom service using systemd by writing a hello world bash script, granting execution permission, and a unit file that enables and starts on boot with systemctl.

Explore how NIC interfaces enable Linux and Windows networking, from LAN cables to Wi-Fi, IP addressing, gateway routing, and virtual networking with vswitch and VirtualBox for enterprise redundancy.

Configure Linux networking with network manager and manual methods. Set static or dynamic IPs, DNS, and gateways using nmcli or config files.

Learn to manage network manager by configuring static ips and gateways via system config network script, aligning device and connection names, and troubleshooting duplicate connections with delete and modify operations.

DNS translates human names to IPs, contrasts the local host file with cloud DNS, and highlights enterprise trade-offs between reliability and performance.

Configure dns on linux by editing resolve config and hosts file, and compare network manager control with edits. Apply name server and search domain settings on ubuntu and centos.

Bond multiple network interfaces into a single master bonding setup to achieve high availability and improved performance, using master and slave NICs with a single virtual IP.

Explore why many companies disable software firewalls in favor of physical devices, and learn how to manage Linux firewall status, disable and mask settings, and opening ports through the DMZ.

Understand how multiple services share one linux server by using distinct ports, with examples like http on 80, ssh on 22, and email on 25, plus container port mapping.

Learn to manage software firewalls with firewall-cmd: open and close ports (tcp/udp), set permanent or temporary rules, reload, and verify access with netstat, telnet, and apache tests.

Understand how disk partitions on a single disk limit growth and upgrades, and how LVM in Red Hat 4 and above enables resizing and flexible volume management.

Learn how to use lvm to manage disks by creating a volume group and a logical volume for the os, prioritizing increasing size over shrinking.

Insert a disk, convert it to an LVM physical volume, create a volume group named app and a 40 gig lv app, then mount at /app and set up fstab.

Extend the logical volume by adding disks and increasing the lv within the volume group, then reflect changes with zfs grow and df without reboot.

Extend the volume group by adding a 300 gb disk, then extend the vg and the logical volume, and resize the filesystem with xfs_growfs to reflect 300 gb.

move the disk from one server to another to recover a failed linux system, create a new operating system on a fresh disk, and troubleshoot database scanning and testing.

Demonstrates moving a 100 gb disk between servers by cloning storage, creating a pv, vg, and a 70 gb lv, then mounting at /dba after activating the vg.