Learn Linux Administration Through Practical Examples

Learn to shrink a volume group by resizing the filesystem and reducing the logical volume, move data if needed, and remove the physical volume, using a live cd.

Add a new virtual hard disk in a VMware Workstation Player VM by configuring the SCSI controller, setting a size (about 5 GB), naming the disk, and completing the setup.

Power off the virtual machine, open Oracle VM VirtualBox settings, go to storage, select a controller, create a new fixed-size disk of 1 gigabyte, name it, and attach hard disk.

Create a physical volume from the new drive, establish a volume group named fgOpt, and carve a full-size logical volume. Format, mount to /opt, and configure fstab for automatic mounting.

Learn to reduce a logical volume by unmounting the file system, resizing the file system, and shrinking the logical volume within its volume group while safely managing physical volumes.

Learn how to manually configure a static IP on a Linux server, troubleshoot network issues, and understand how firewall rules and network configuration files impact access.

Learn to view and change the host name using network configuration files and the command line. Edit the hostname file or use the hostname command to rename the machine.

Learn how DNS resolves domain names to IP addresses by querying ordered name servers and inspect responses on port 53, while tuning timeouts and retries.

Configure the /etc/hosts file to locally resolve names to ip addresses and block access to certain websites. Save changes and restart the networking service to apply them.

Explore how a Linux system resolves a domain by first checking the hosts file, then querying the configured DNS servers in order to obtain name information.

Explore the ip vs ifconfig commands, showing how to configure network interfaces, bring them up or down, view interfaces and routing tables, and add routes and a default gateway.

Explore how to view and manage routes, set default gateways, and test reachability using route commands. Learn to distinguish routing actions from firewall rules and use iptables for traffic control.

Explore securing remote access with SSH by using a key pair, enabling passwordless logins, and optionally protecting private keys with a passphrase while disabling root password authentication.

Learn to configure iptables-persistent to save firewall rules across reboots, including startup scripts, for IPv4 and IPv6. Implement selective allow and block rules on ports 22, 80, and 443.

Explore a practical approach to diagnosing Linux network issues from physical layer to DNS, starting with NIC status and IP configuration, then firewall, gateway, IP stack, DNS and ISP checks.

Learn to diagnose Linux connectivity with the ping command, verify network interfaces and assigned IPs using ifconfig, and troubleshoot DNS, firewall, and gateway reachability to external hosts such as Google.

Explain how a ping resolves DNS to an IP, uses the gateway's MAC, and travels via switch, gateway, router, and default gateway to the ISP, with a reverse-path reply.

Learn how the traceroute command helps troubleshoot connectivity by showing each hop and the path packets take to reach a destination such as google.com, including gateway and next hops.

Explore netstat and the modern ss tool to monitor tcp and udp connections, view listening and established ports, inspect routing tables, and interpret packet statistics with practical Linux administration examples.

Interpret tcpdump outputs by identifying the source, the destination, ports, and flags, and understand the TCP three-way handshake, parameter negotiation, sequence numbers, and acknowledgments.

Explore practical approaches to diagnose and troubleshoot system issues by monitoring memory, cpu, and swap usage, identifying running processes, scheduling jobs, and checking logs for root causes.

Learn how swap space works, why swappiness matters, and how to configure a separate swap partition, adjust swappiness from 1–100, and apply temporary or persistent changes.

Identify the system's resources by examining CPU details, kernel version, host name, and architecture, then review /proc data and PCI devices, plus storage with partitions and volume groups.

Explore how to check your server’s resource usage, including ram and swap with free and /proc/meminfo, and analyze disk usage with du options for depth and time to identify bottlenecks.

Use the watch command to monitor system resources in real time, refreshing every two seconds. Track disk space, memory, and network packets to analyze resource utilization.

Learn to check running processes with ps aux, view user, pid, and memory usage, and sort by cpu to reveal top consumers using nice and grep.

Learn to use lsof to view open files by process or user. Identify file types and directories like /var/log, and safely unmount busy mount points.

Learn where linux log files live, usually in /var/log, and use grep, head, tail, and tail -f to search and monitor logs in real time, including dmesg and lastlog.

Learn how logrotate rotates and compresses log files to prevent disk space issues, using frequency and size limits, keep counts, and per-application blocks.

Schedule one-time tasks on a Linux server with the at command, view the queue with atq, and inspect or remove jobs using related commands.

Learn practical Linux administration by creating and deleting users and groups, and assigning users to groups. Explore unlocking accounts, password setup, home directories, and switching users for verification.

Learn to manage groups and delete users in linux by adding users with usermod -aG, listing members with the groups and the members tools, and removing users with userdel.

Lock and unlock Linux user accounts by adjusting expiry with chage. Use chage -E 0 <user> to lock, chage -E -1 <user> to unlock, and verify with chage -l <user>.

Learn how to enforce Linux disk quotas by configuring user and group quotas, editing mount options, and managing soft and hard limits for home directories.