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  • Computer Basics
    • Operating System Basics
    • Processes explained
    • Difference Between Process and Thread
    • The Basics of Hypervisors
      • A simple explanation of virtualization by VMinformer
      • What is a Hypervisor?
    • What’s a Kernel?
    • Processes and VM Videos
      • Create, Execute & Exit from a Process | frok() System Call
      • Process, Process Stack, PCB & Attributes
  • Linux
    • Linux Basics
      • What is Linux?
        • What is a Linux Package?
        • Stages of Linux booting process – explanation, step by step
        • Whats an Inode
        • Explanation-System calls and System call types in operating system
        • Linux Package Management
        • How the ls -l command works
        • Linux Isolation Basics
        • Understanding Linux File Permissions
        • Understanding UMASK value in Linux
        • What is Umask and How To Setup Default umask Under Linux?
        • File descriptor
        • Understanding Special Permission SGID in Linux
        • Searching with grep
        • Introduction to Linux and Basic commands
        • fstab explained
        • Introduction to mounting filesystems in Linux
      • SSH
        • What is Secure Shell (SSH)
        • SSH Layers
        • SSH using Putty
        • 4 Reasons Why SSH Connection Fails
        • Enabling MFA on Ubuntu and Amazon Linux
        • Enabling MFA on your Instance
        • Howto remove Google authenticator from SSH logins
        • How to use multiplexing to speed up the SSH
        • How to access RDP over SSH tunnel
      • Ram & Disks
        • What is the difference between memory and disk storage?
        • How to check disk space utilization
        • Monitoring RAM
        • RAID
      • Video tutorial on extending swap partition and creating a swapfile
      • Commands
        • 15-basic-curl-command-in-linux-with-practical-examples
        • Linux users and permissions assist guide
      • SystemD
        • Systemd Boot Process, a closer look
        • Step by Step Linux boot process with GRUB2 and systemd in RHEL 7 / CentOS 7
        • Useful SystemD commands and info
        • The Story Behind ‘init’ and ‘systemd’
        • Basic journal use
        • Unit files: what are they?
        • Unit dependencies
      • What is a Unix Socket?
      • How to check disk space on Unix servers
      • 3 commands to reboot Linux (plus 4 more ways to do it safely)
      • See Detailed History Of yum history Commands
      • How to Transfer Files with Rsync over SSH
      • How to Use the mkfs Command on Linux
    • Linux +
      • GRUB bootloader – Full tutorial
      • How to Change Kernel Runtime Parameters in a Persistent and Non-Persistent Way
      • Linux Basics – LVM (Logical Volume Manager)
      • A video overview of OOM(Out Of Memory)
      • Linux Storage Stack Diagram
      • Basics-of-bash-for-beginners
      • CPU & LOAD AVERAGE
        • Linux Load Averages: Solving the Mystery
      • How to Run Sudo Command Without Password
      • Virtualization
        • Difference between PV and HVM virtualization
        • Virtualization Performance: Zones, KVM, Xen
      • Commands
        • strace explained
      • Ram & Disk Space
        • Why is space not being freed from disk after deleting a file in Red Hat Enterprise Linux?
        • Understanding I/O: Random vs Sequential
      • Memory Management
        • Introduction to Memory Management in Linux
      • Processes
        • Process, Process Stack, PCB & Attributes
        • Create, Execute & Exit from a Process | frok() System Call
        • CPU Context Switching & Its Overheads
        • What is an Interrupt? Types of Interrupts
        • CPU Scheduling: FCFS, SJF, SRTF, Round Robin
        • Background and Foreground Processes
      • Virtual filesystems in Linux: Why we need them and how they work
      • Overview of Forks, Threads, and Asynchronous I/O
    • RHEL(RedHat)
      • File-management-red-hat-enterprise-linux-8
      • Enable ENA driver on EC2 for RHEL 6 & 7
    • Amazon Linux 2
      • How to install XRDP in Amazon Linux 2
    • Centos 8
      • Centos8 dig command not found. How to install dig on centos8
      • How to install whois on RHEL 8 / CentOS 8
    • Ubuntu
      • Ubuntu 18.04 remove all unused old kernels
    • SUSE
    • Tools
      • Filezilla
      • SSH using Putty
      • WinSCP
        • WinSCP Portable 5.15.2 (ftp, sftp, scp client) Released
    • My Study Guide
      • CPU
        • A Guide to the Linux “Top” Command
        • Understanding CPU Steal Time – when should you be worried?
        • CPU Steal Time. Now on Amazon EC2
        • USER SPACE VS KERNEL SPACE
        • What is the Difference Between Hardware and Software Interrupt
        • What exactly is “iowait”?
        • Difference Between Process And Thread in Linux
        • Operating Systems | States of a process
      • Linux OS related
        • Boot process
          • An in depth look at the Linux Boot process
          • Systemd Boot Process, a closer look
          • Stages of Linux booting process – explanation, step by step
          • 6 Stages of Linux Boot Process (Startup Sequence) sysVinit:
          • Step by Step Linux boot process with GRUB2 and systemd in RHEL 7 / CentOS 7
        • Init and Initramfs
          • Initrd vs Initramfs
          • Do you need initramfs to boot?
        • The difference between booting MBR and GPT with GRUB
        • The Master Boot Record (MBR) and Why it is Necessary?
        • GRUB bootloader – Full tutorial
      • Memory
        • free command
        • Buffer vs Cache
        • How to Clear RAM Memory Cache, Buffer and Swap Space on Linux
        • OOM explained
        • How to Configure the Linux Out-of-Memory Killer
        • Surviving the Linux OOM Killer
      • Disk
        • Amazon EBS
        • Linux iostat command
        • How to Read Linux Iostat’s Output and Interpret System Performance
        • Video tutorial on extending swap partition and creating a swapfile
        • Linux Basics – LVM (Logical Volume Manager)
        • RAID
        • Video tutorial on extending swap partition and creating a swapfile
  • Networking
    • Networking basics
      • Introduction to Networking
        • What is a Computer Network?
        • Types of Networks
        • MAN
        • WAN
        • Parts of a Network
        • How the internet works
        • Servers
        • Clients and Hosts
        • Network Interface Card NIC
        • What is a Protocol
        • Bus Topology
        • Ring Topology
        • Star Topology
        • Mesh Topology
        • OSI Model
        • More on the OSI Model
      • TCP/IP explained
      • TCP connection states
      • TCP three way handshake
      • TCP/IP Ports and Sockets Explained
      • DNS Name Resolution Process
      • What happens when we hit a URL in our browser
      • What is SSL
      • SSL or TLS handshake
      • What is an SSL Certificate and How Does it Work?
      • DHCP Explained
      • The Certificate Authority vs. The Handshake
    • Networking +
      • A tcpdump Tutorial and Primer with Examples
      • How To Use Traceroute and MTR to Diagnose Network Issues
      • tcpdump command to capture full-sized packets
      • Commands
        • Commands to monitor network bandwidth on Linux server
        • Linux Route Command Examples (How to Add Route in Linux)
  • Application Services and Packages
    • Apache
      • What is Apache?
      • Apache Basics Video
      • Apache Cheat Sheet
      • Apache Performance Tuning: MPM Modules
      • How To Use Apache as a Reverse Proxy with mod_proxy on CentOS 7
      • Tune memory allocation for an Apache web server
      • Failed to restart httpsd.service: The name org.freedesktop.PolicyKit1 was not provided by any .service files
      • Redirecting from one URL to another using .htaccess
      • USING .HTACCESS REWRITE RULES
      • URL Rewriting for Beginners
      • How to Enable Apache Userdir Module on RHEL/CentOS
      • How to set up password authentication in apache (httpd) with htpasswd and .htaccess on RHEL / CentOS 7
      • How to redirect HTTP to HTTPS Using .htaccess
      • How to Enable TLS 1.3 in Apache and Nginx
      • Apache Benchmark
    • Nginx
      • How To Install Linux, Nginx, MySQL, PHP (LEMP stack) on Ubuntu 18.04
      • Nginx Bible
      • Basic Nginx commands
      • Basic configuration parameters
      • SSL certificate Installation
      • Full configuration Example
      • Nginx Rewrite examples
      • Nginx redirect from www to none www domain name
      • How to Set Up an Nginx Certbot
      • Urgent security issue in NGINX/php-fpm
      • Moving from Apache2 to Nginx Webserver
    • PHP
      • What is PHP?
      • The PHP Process Explained
      • What does PHP-FPM do?
      • PHP troubleshooting tip
      • max_execution_time in php explained
      • Why You Should Upgrade WordPress to PHP 7 Now Rather Than Later
    • MYSQL
      • What Is MySQL?
      • MySQL Command cheat sheet
      • Creating and editing MySQL DB Dumps
      • MySQL – MySQL Introduction
      • MySQL – Structure Introduction
      • MySQL – Data Types Introduction
    • Fail2ban
    • Magento2
      • Magento explained plus commands for an easy install on Ubuntu 16.04
    • VNC Installation on Ubuntu
    • How to install XRDP in Amazon Linux 2
  • My issues
    • WordPress
      • WordPress FTP error
      • Unable to upload file to WordPress
      • WordPress Posts Returning 404 Error
      • How to Fix the 500 Internal Server Error on Your WordPress Website
      • How to Fix Corrupted Files and Databases in WordPress
      • Max_upload exceeded..!!! WordPress
      • 6 Ways To Increase the Maximum Upload File Size in WordPress
    • Being prompted for password after not setting one (RHEL/Amazon Linux)
    • Unable to transfer files from one instance to another using SCP
    • Website running and reachable via a browser however giving a 403 when running a CURL
    • Issue installing Cerbot on Amazon Linux 2
    • How to restore “Kernel panic – not syncing: VFS: Unable to mount root fs on unknown-block(0,0)”
    • Renewing your SSL certificate using Certbot/Letsencrypt manually:
  • AWS(Amazon Web Services)
    • Instance Health Checks failing
      • How to fix a Kernel panic – not syncing: VFS: Unable to mount root fs on unknown-block(0,0)
      • Reasons why an instance with root on LVM might fail to boot
      • Instance failing health checks with a Kernel Offset: disabled error
    • EC2 SSH ISSUES
      • Injecting userdata to allow ssh
    • Amazon EBS
    • AWS Workarounds
      • Steps to install python3.7 on Amazon Linux 1
      • Using userdata to resolve ssh issues to your EC2 instance
      • How to use the same SSH key pair in all AWS regions
      • Accidentally enabled UFW on your Ubuntu instance and cant SSH as a result?
    • Lightsail Loadbalancer failing health checks
    • AWS Docs
      • How can I avoid DNS resolution failures with EC2 Linux?
      • Extending a Linux File System after Resizing the Volume
    • Service Introduction Videos
      • What is AWS?
      • Introduction to Amazon EC2
      • Amazon Elastic Block Store (EBS) Overview
    • Troubleshooting videos
      • How do I recover access to my EC2 instances if I lost my SSH key pair?
      • How do I move my EC2 instance to another subnet, Availability Zone, VPC, or region?
  • Troubleshooting
    • Server A Can’t Talk to Server B
    • Troubleshoot Slow Networks
    • How To Troubleshoot Common Site Issues on a Linux Server
    • How to fix a Kernel panic – not syncing: VFS: Unable to mount root fs on unknown-block(0,0)
    • How to fix high memory usage in Linux ?
    • Troubleshooting a Linux kernel panic after patching
    • Reproducing a “Kernel panic – not syncing: VFS: Unable to mount root fs on unknown-block(0,0)”
  • Articles
    • How to get notified whenever someone logs in via SSH?
    • procSpy : Python tool that monitors and logs user-run commands on a Linux system
    • How to identify duplicate files on Linux
    • Power of SSH Tunneling
    • Linux commands you should never run on your system
  • Redis
    • ElastiCache
      • Redis restore from S3 snapshot fails
    • An introduction to Redis data types and abstractions
    • Redis – Commands
    • Redis – Keys
    • Redis – Strings
    • Redis – Hashes
    • Redis – Lists
    • Redis – Sets
    • Redis – Sorted Sets
  • My Curriculum Vitae (CV)
LinuxByImraan LinuxByImraan
Primary Menu
  • Computer Basics
    • Operating System Basics
    • Processes explained
    • Difference Between Process and Thread
    • The Basics of Hypervisors
      • A simple explanation of virtualization by VMinformer
      • What is a Hypervisor?
    • What’s a Kernel?
    • Processes and VM Videos
      • Create, Execute & Exit from a Process | frok() System Call
      • Process, Process Stack, PCB & Attributes
  • Linux
    • Linux Basics
      • What is Linux?
        • What is a Linux Package?
        • Stages of Linux booting process – explanation, step by step
        • Whats an Inode
        • Explanation-System calls and System call types in operating system
        • Linux Package Management
        • How the ls -l command works
        • Linux Isolation Basics
        • Understanding Linux File Permissions
        • Understanding UMASK value in Linux
        • What is Umask and How To Setup Default umask Under Linux?
        • File descriptor
        • Understanding Special Permission SGID in Linux
        • Searching with grep
        • Introduction to Linux and Basic commands
        • fstab explained
        • Introduction to mounting filesystems in Linux
      • SSH
        • What is Secure Shell (SSH)
        • SSH Layers
        • SSH using Putty
        • 4 Reasons Why SSH Connection Fails
        • Enabling MFA on Ubuntu and Amazon Linux
        • Enabling MFA on your Instance
        • Howto remove Google authenticator from SSH logins
        • How to use multiplexing to speed up the SSH
        • How to access RDP over SSH tunnel
      • Ram & Disks
        • What is the difference between memory and disk storage?
        • How to check disk space utilization
        • Monitoring RAM
        • RAID
      • Video tutorial on extending swap partition and creating a swapfile
      • Commands
        • 15-basic-curl-command-in-linux-with-practical-examples
        • Linux users and permissions assist guide
      • SystemD
        • Systemd Boot Process, a closer look
        • Step by Step Linux boot process with GRUB2 and systemd in RHEL 7 / CentOS 7
        • Useful SystemD commands and info
        • The Story Behind ‘init’ and ‘systemd’
        • Basic journal use
        • Unit files: what are they?
        • Unit dependencies
      • What is a Unix Socket?
      • How to check disk space on Unix servers
      • 3 commands to reboot Linux (plus 4 more ways to do it safely)
      • See Detailed History Of yum history Commands
      • How to Transfer Files with Rsync over SSH
      • How to Use the mkfs Command on Linux
    • Linux +
      • GRUB bootloader – Full tutorial
      • How to Change Kernel Runtime Parameters in a Persistent and Non-Persistent Way
      • Linux Basics – LVM (Logical Volume Manager)
      • A video overview of OOM(Out Of Memory)
      • Linux Storage Stack Diagram
      • Basics-of-bash-for-beginners
      • CPU & LOAD AVERAGE
        • Linux Load Averages: Solving the Mystery
      • How to Run Sudo Command Without Password
      • Virtualization
        • Difference between PV and HVM virtualization
        • Virtualization Performance: Zones, KVM, Xen
      • Commands
        • strace explained
      • Ram & Disk Space
        • Why is space not being freed from disk after deleting a file in Red Hat Enterprise Linux?
        • Understanding I/O: Random vs Sequential
      • Memory Management
        • Introduction to Memory Management in Linux
      • Processes
        • Process, Process Stack, PCB & Attributes
        • Create, Execute & Exit from a Process | frok() System Call
        • CPU Context Switching & Its Overheads
        • What is an Interrupt? Types of Interrupts
        • CPU Scheduling: FCFS, SJF, SRTF, Round Robin
        • Background and Foreground Processes
      • Virtual filesystems in Linux: Why we need them and how they work
      • Overview of Forks, Threads, and Asynchronous I/O
    • RHEL(RedHat)
      • File-management-red-hat-enterprise-linux-8
      • Enable ENA driver on EC2 for RHEL 6 & 7
    • Amazon Linux 2
      • How to install XRDP in Amazon Linux 2
    • Centos 8
      • Centos8 dig command not found. How to install dig on centos8
      • How to install whois on RHEL 8 / CentOS 8
    • Ubuntu
      • Ubuntu 18.04 remove all unused old kernels
    • SUSE
    • Tools
      • Filezilla
      • SSH using Putty
      • WinSCP
        • WinSCP Portable 5.15.2 (ftp, sftp, scp client) Released
    • My Study Guide
      • CPU
        • A Guide to the Linux “Top” Command
        • Understanding CPU Steal Time – when should you be worried?
        • CPU Steal Time. Now on Amazon EC2
        • USER SPACE VS KERNEL SPACE
        • What is the Difference Between Hardware and Software Interrupt
        • What exactly is “iowait”?
        • Difference Between Process And Thread in Linux
        • Operating Systems | States of a process
      • Linux OS related
        • Boot process
          • An in depth look at the Linux Boot process
          • Systemd Boot Process, a closer look
          • Stages of Linux booting process – explanation, step by step
          • 6 Stages of Linux Boot Process (Startup Sequence) sysVinit:
          • Step by Step Linux boot process with GRUB2 and systemd in RHEL 7 / CentOS 7
        • Init and Initramfs
          • Initrd vs Initramfs
          • Do you need initramfs to boot?
        • The difference between booting MBR and GPT with GRUB
        • The Master Boot Record (MBR) and Why it is Necessary?
        • GRUB bootloader – Full tutorial
      • Memory
        • free command
        • Buffer vs Cache
        • How to Clear RAM Memory Cache, Buffer and Swap Space on Linux
        • OOM explained
        • How to Configure the Linux Out-of-Memory Killer
        • Surviving the Linux OOM Killer
      • Disk
        • Amazon EBS
        • Linux iostat command
        • How to Read Linux Iostat’s Output and Interpret System Performance
        • Video tutorial on extending swap partition and creating a swapfile
        • Linux Basics – LVM (Logical Volume Manager)
        • RAID
        • Video tutorial on extending swap partition and creating a swapfile
  • Networking
    • Networking basics
      • Introduction to Networking
        • What is a Computer Network?
        • Types of Networks
        • MAN
        • WAN
        • Parts of a Network
        • How the internet works
        • Servers
        • Clients and Hosts
        • Network Interface Card NIC
        • What is a Protocol
        • Bus Topology
        • Ring Topology
        • Star Topology
        • Mesh Topology
        • OSI Model
        • More on the OSI Model
      • TCP/IP explained
      • TCP connection states
      • TCP three way handshake
      • TCP/IP Ports and Sockets Explained
      • DNS Name Resolution Process
      • What happens when we hit a URL in our browser
      • What is SSL
      • SSL or TLS handshake
      • What is an SSL Certificate and How Does it Work?
      • DHCP Explained
      • The Certificate Authority vs. The Handshake
    • Networking +
      • A tcpdump Tutorial and Primer with Examples
      • How To Use Traceroute and MTR to Diagnose Network Issues
      • tcpdump command to capture full-sized packets
      • Commands
        • Commands to monitor network bandwidth on Linux server
        • Linux Route Command Examples (How to Add Route in Linux)
  • Application Services and Packages
    • Apache
      • What is Apache?
      • Apache Basics Video
      • Apache Cheat Sheet
      • Apache Performance Tuning: MPM Modules
      • How To Use Apache as a Reverse Proxy with mod_proxy on CentOS 7
      • Tune memory allocation for an Apache web server
      • Failed to restart httpsd.service: The name org.freedesktop.PolicyKit1 was not provided by any .service files
      • Redirecting from one URL to another using .htaccess
      • USING .HTACCESS REWRITE RULES
      • URL Rewriting for Beginners
      • How to Enable Apache Userdir Module on RHEL/CentOS
      • How to set up password authentication in apache (httpd) with htpasswd and .htaccess on RHEL / CentOS 7
      • How to redirect HTTP to HTTPS Using .htaccess
      • How to Enable TLS 1.3 in Apache and Nginx
      • Apache Benchmark
    • Nginx
      • How To Install Linux, Nginx, MySQL, PHP (LEMP stack) on Ubuntu 18.04
      • Nginx Bible
      • Basic Nginx commands
      • Basic configuration parameters
      • SSL certificate Installation
      • Full configuration Example
      • Nginx Rewrite examples
      • Nginx redirect from www to none www domain name
      • How to Set Up an Nginx Certbot
      • Urgent security issue in NGINX/php-fpm
      • Moving from Apache2 to Nginx Webserver
    • PHP
      • What is PHP?
      • The PHP Process Explained
      • What does PHP-FPM do?
      • PHP troubleshooting tip
      • max_execution_time in php explained
      • Why You Should Upgrade WordPress to PHP 7 Now Rather Than Later
    • MYSQL
      • What Is MySQL?
      • MySQL Command cheat sheet
      • Creating and editing MySQL DB Dumps
      • MySQL – MySQL Introduction
      • MySQL – Structure Introduction
      • MySQL – Data Types Introduction
    • Fail2ban
    • Magento2
      • Magento explained plus commands for an easy install on Ubuntu 16.04
    • VNC Installation on Ubuntu
    • How to install XRDP in Amazon Linux 2
  • My issues
    • WordPress
      • WordPress FTP error
      • Unable to upload file to WordPress
      • WordPress Posts Returning 404 Error
      • How to Fix the 500 Internal Server Error on Your WordPress Website
      • How to Fix Corrupted Files and Databases in WordPress
      • Max_upload exceeded..!!! WordPress
      • 6 Ways To Increase the Maximum Upload File Size in WordPress
    • Being prompted for password after not setting one (RHEL/Amazon Linux)
    • Unable to transfer files from one instance to another using SCP
    • Website running and reachable via a browser however giving a 403 when running a CURL
    • Issue installing Cerbot on Amazon Linux 2
    • How to restore “Kernel panic – not syncing: VFS: Unable to mount root fs on unknown-block(0,0)”
    • Renewing your SSL certificate using Certbot/Letsencrypt manually:
  • AWS(Amazon Web Services)
    • Instance Health Checks failing
      • How to fix a Kernel panic – not syncing: VFS: Unable to mount root fs on unknown-block(0,0)
      • Reasons why an instance with root on LVM might fail to boot
      • Instance failing health checks with a Kernel Offset: disabled error
    • EC2 SSH ISSUES
      • Injecting userdata to allow ssh
    • Amazon EBS
    • AWS Workarounds
      • Steps to install python3.7 on Amazon Linux 1
      • Using userdata to resolve ssh issues to your EC2 instance
      • How to use the same SSH key pair in all AWS regions
      • Accidentally enabled UFW on your Ubuntu instance and cant SSH as a result?
    • Lightsail Loadbalancer failing health checks
    • AWS Docs
      • How can I avoid DNS resolution failures with EC2 Linux?
      • Extending a Linux File System after Resizing the Volume
    • Service Introduction Videos
      • What is AWS?
      • Introduction to Amazon EC2
      • Amazon Elastic Block Store (EBS) Overview
    • Troubleshooting videos
      • How do I recover access to my EC2 instances if I lost my SSH key pair?
      • How do I move my EC2 instance to another subnet, Availability Zone, VPC, or region?
  • Troubleshooting
    • Server A Can’t Talk to Server B
    • Troubleshoot Slow Networks
    • How To Troubleshoot Common Site Issues on a Linux Server
    • How to fix a Kernel panic – not syncing: VFS: Unable to mount root fs on unknown-block(0,0)
    • How to fix high memory usage in Linux ?
    • Troubleshooting a Linux kernel panic after patching
    • Reproducing a “Kernel panic – not syncing: VFS: Unable to mount root fs on unknown-block(0,0)”
  • Articles
    • How to get notified whenever someone logs in via SSH?
    • procSpy : Python tool that monitors and logs user-run commands on a Linux system
    • How to identify duplicate files on Linux
    • Power of SSH Tunneling
    • Linux commands you should never run on your system
  • Redis
    • ElastiCache
      • Redis restore from S3 snapshot fails
    • An introduction to Redis data types and abstractions
    • Redis – Commands
    • Redis – Keys
    • Redis – Strings
    • Redis – Hashes
    • Redis – Lists
    • Redis – Sets
    • Redis – Sorted Sets
  • My Curriculum Vitae (CV)

Amazon Linux 2

About Me

Imraan Abrahams

Currently employed as a Linux Cloud Support Engineer at Amazon Web Services.

What is AWS?

https://www.youtube.com/watch?v=mZ5H8sn_2ZI

Introduction to Amazon EC2

https://www.youtube.com/watch?v=TsRBftzZsQo

Elastic Block Store (EBS) Overview

https://www.youtube.com/watch?v=77qLAl-lRpo

How do I convert ssh .pem key files into .ppk key files and vice versa?

https://www.youtube.com/watch?v=vCMDHPHBen4&list=PLhr1KZpdzukfdjsOHZ-BazZt1iK1J8UUw&index=179

Tune memory allocation for an Apache web

https://www.youtube.com/watch?v=Qyr3geZwXQY

Update GRUB to load a previous kernel

https://www.youtube.com/watch?v=QiMpJi2YWxA&index=6&list=PLhr1KZpdzukfdjsOHZ-BazZt1iK1J8UUw

How does DNS work, and how do I troubleshoot partial DNS failures?

https://www.youtube.com/watch?v=qIetJGi7TW0&list=PLhr1KZpdzukfdjsOHZ-BazZt1iK1J8UUw&index=23

How do I expand an EBS root volume of a Linux instance?

https://www.youtube.com/watch?v=9znrrZNW_9o&list=PLhr1KZpdzukfdjsOHZ-BazZt1iK1J8UUw&index=268

How do I create a subdomain with AWS Route 53?

https://www.youtube.com/watch?v=kpHeE3HZHZA&list=PLhr1KZpdzukfdjsOHZ-BazZt1iK1J8UUw&index=8

How do I extend my Linux filesystem using Elastic Volumes?

https://www.youtube.com/watch?v=yYbX5U6CsKM&list=PLhr1KZpdzukfdjsOHZ-BazZt1iK1J8UUw&index=8&t=0s

How do I migrate my DNS service for an existing domain to Amazon Route 53?

https://www.youtube.com/watch?v=W4FPZ29Trpw&list=PLhr1KZpdzukfdjsOHZ-BazZt1iK1J8UUw&index=293

How to enable secondary interface Ubuntu

https://www.youtube.com/watch?v=RmwGYXchb4E&list=PLhr1KZpdzukfdjsOHZ-BazZt1iK1J8UUw&index=22

Add an additional SSH User account with my cloud-init and user data

https://www.youtube.com/watch?v=OGj0Lj5DOBg&list=PLhr1KZpdzukfdjsOHZ-BazZt1iK1J8UUw&index=13&t=0s

“How do I set up a NAT gateway?”

https://www.youtube.com/watch?v=zRMMbzw7SsA&list=PLhr1KZpdzukfdjsOHZ-BazZt1iK1J8UUw&index=362
  • Computer Basics
    • Operating System Basics
    • Processes explained
    • Difference Between Process and Thread
    • The Basics of Hypervisors
      • A simple explanation of virtualization by VMinformer
      • What is a Hypervisor?
    • What’s a Kernel?
    • Processes and VM Videos
      • Create, Execute & Exit from a Process | frok() System Call
      • Process, Process Stack, PCB & Attributes
  • Linux
    • Linux Basics
      • What is Linux?
        • What is a Linux Package?
        • Stages of Linux booting process – explanation, step by step
        • Whats an Inode
        • Explanation-System calls and System call types in operating system
        • Linux Package Management
        • How the ls -l command works
        • Linux Isolation Basics
        • Understanding Linux File Permissions
        • Understanding UMASK value in Linux
        • What is Umask and How To Setup Default umask Under Linux?
        • File descriptor
        • Understanding Special Permission SGID in Linux
        • Searching with grep
        • Introduction to Linux and Basic commands
        • fstab explained
        • Introduction to mounting filesystems in Linux
      • SSH
        • What is Secure Shell (SSH)
        • SSH Layers
        • SSH using Putty
        • 4 Reasons Why SSH Connection Fails
        • Enabling MFA on Ubuntu and Amazon Linux
        • Enabling MFA on your Instance
        • Howto remove Google authenticator from SSH logins
        • How to use multiplexing to speed up the SSH
        • How to access RDP over SSH tunnel
      • Ram & Disks
        • What is the difference between memory and disk storage?
        • How to check disk space utilization
        • Monitoring RAM
        • RAID
      • Video tutorial on extending swap partition and creating a swapfile
      • Commands
        • 15-basic-curl-command-in-linux-with-practical-examples
        • Linux users and permissions assist guide
      • SystemD
        • Systemd Boot Process, a closer look
        • Step by Step Linux boot process with GRUB2 and systemd in RHEL 7 / CentOS 7
        • Useful SystemD commands and info
        • The Story Behind ‘init’ and ‘systemd’
        • Basic journal use
        • Unit files: what are they?
        • Unit dependencies
      • What is a Unix Socket?
      • How to check disk space on Unix servers
      • 3 commands to reboot Linux (plus 4 more ways to do it safely)
      • See Detailed History Of yum history Commands
      • How to Transfer Files with Rsync over SSH
      • How to Use the mkfs Command on Linux
    • Linux +
      • GRUB bootloader – Full tutorial
      • How to Change Kernel Runtime Parameters in a Persistent and Non-Persistent Way
      • Linux Basics – LVM (Logical Volume Manager)
      • A video overview of OOM(Out Of Memory)
      • Linux Storage Stack Diagram
      • Basics-of-bash-for-beginners
      • CPU & LOAD AVERAGE
        • Linux Load Averages: Solving the Mystery
      • How to Run Sudo Command Without Password
      • Virtualization
        • Difference between PV and HVM virtualization
        • Virtualization Performance: Zones, KVM, Xen
      • Commands
        • strace explained
      • Ram & Disk Space
        • Why is space not being freed from disk after deleting a file in Red Hat Enterprise Linux?
        • Understanding I/O: Random vs Sequential
      • Memory Management
        • Introduction to Memory Management in Linux
      • Processes
        • Process, Process Stack, PCB & Attributes
        • Create, Execute & Exit from a Process | frok() System Call
        • CPU Context Switching & Its Overheads
        • What is an Interrupt? Types of Interrupts
        • CPU Scheduling: FCFS, SJF, SRTF, Round Robin
        • Background and Foreground Processes
      • Virtual filesystems in Linux: Why we need them and how they work
      • Overview of Forks, Threads, and Asynchronous I/O
    • RHEL(RedHat)
      • File-management-red-hat-enterprise-linux-8
      • Enable ENA driver on EC2 for RHEL 6 & 7
    • Amazon Linux 2
      • How to install XRDP in Amazon Linux 2
    • Centos 8
      • Centos8 dig command not found. How to install dig on centos8
      • How to install whois on RHEL 8 / CentOS 8
    • Ubuntu
      • Ubuntu 18.04 remove all unused old kernels
    • SUSE
    • Tools
      • Filezilla
      • SSH using Putty
      • WinSCP
        • WinSCP Portable 5.15.2 (ftp, sftp, scp client) Released
    • My Study Guide
      • CPU
        • A Guide to the Linux “Top” Command
        • Understanding CPU Steal Time – when should you be worried?
        • CPU Steal Time. Now on Amazon EC2
        • USER SPACE VS KERNEL SPACE
        • What is the Difference Between Hardware and Software Interrupt
        • What exactly is “iowait”?
        • Difference Between Process And Thread in Linux
        • Operating Systems | States of a process
      • Linux OS related
        • Boot process
          • An in depth look at the Linux Boot process
          • Systemd Boot Process, a closer look
          • Stages of Linux booting process – explanation, step by step
          • 6 Stages of Linux Boot Process (Startup Sequence) sysVinit:
          • Step by Step Linux boot process with GRUB2 and systemd in RHEL 7 / CentOS 7
        • Init and Initramfs
          • Initrd vs Initramfs
          • Do you need initramfs to boot?
        • The difference between booting MBR and GPT with GRUB
        • The Master Boot Record (MBR) and Why it is Necessary?
        • GRUB bootloader – Full tutorial
      • Memory
        • free command
        • Buffer vs Cache
        • How to Clear RAM Memory Cache, Buffer and Swap Space on Linux
        • OOM explained
        • How to Configure the Linux Out-of-Memory Killer
        • Surviving the Linux OOM Killer
      • Disk
        • Amazon EBS
        • Linux iostat command
        • How to Read Linux Iostat’s Output and Interpret System Performance
        • Video tutorial on extending swap partition and creating a swapfile
        • Linux Basics – LVM (Logical Volume Manager)
        • RAID
        • Video tutorial on extending swap partition and creating a swapfile
  • Networking
    • Networking basics
      • Introduction to Networking
        • What is a Computer Network?
        • Types of Networks
        • MAN
        • WAN
        • Parts of a Network
        • How the internet works
        • Servers
        • Clients and Hosts
        • Network Interface Card NIC
        • What is a Protocol
        • Bus Topology
        • Ring Topology
        • Star Topology
        • Mesh Topology
        • OSI Model
        • More on the OSI Model
      • TCP/IP explained
      • TCP connection states
      • TCP three way handshake
      • TCP/IP Ports and Sockets Explained
      • DNS Name Resolution Process
      • What happens when we hit a URL in our browser
      • What is SSL
      • SSL or TLS handshake
      • What is an SSL Certificate and How Does it Work?
      • DHCP Explained
      • The Certificate Authority vs. The Handshake
    • Networking +
      • A tcpdump Tutorial and Primer with Examples
      • How To Use Traceroute and MTR to Diagnose Network Issues
      • tcpdump command to capture full-sized packets
      • Commands
        • Commands to monitor network bandwidth on Linux server
        • Linux Route Command Examples (How to Add Route in Linux)
  • Application Services and Packages
    • Apache
      • What is Apache?
      • Apache Basics Video
      • Apache Cheat Sheet
      • Apache Performance Tuning: MPM Modules
      • How To Use Apache as a Reverse Proxy with mod_proxy on CentOS 7
      • Tune memory allocation for an Apache web server
      • Failed to restart httpsd.service: The name org.freedesktop.PolicyKit1 was not provided by any .service files
      • Redirecting from one URL to another using .htaccess
      • USING .HTACCESS REWRITE RULES
      • URL Rewriting for Beginners
      • How to Enable Apache Userdir Module on RHEL/CentOS
      • How to set up password authentication in apache (httpd) with htpasswd and .htaccess on RHEL / CentOS 7
      • How to redirect HTTP to HTTPS Using .htaccess
      • How to Enable TLS 1.3 in Apache and Nginx
      • Apache Benchmark
    • Nginx
      • How To Install Linux, Nginx, MySQL, PHP (LEMP stack) on Ubuntu 18.04
      • Nginx Bible
      • Basic Nginx commands
      • Basic configuration parameters
      • SSL certificate Installation
      • Full configuration Example
      • Nginx Rewrite examples
      • Nginx redirect from www to none www domain name
      • How to Set Up an Nginx Certbot
      • Urgent security issue in NGINX/php-fpm
      • Moving from Apache2 to Nginx Webserver
    • PHP
      • What is PHP?
      • The PHP Process Explained
      • What does PHP-FPM do?
      • PHP troubleshooting tip
      • max_execution_time in php explained
      • Why You Should Upgrade WordPress to PHP 7 Now Rather Than Later
    • MYSQL
      • What Is MySQL?
      • MySQL Command cheat sheet
      • Creating and editing MySQL DB Dumps
      • MySQL – MySQL Introduction
      • MySQL – Structure Introduction
      • MySQL – Data Types Introduction
    • Fail2ban
    • Magento2
      • Magento explained plus commands for an easy install on Ubuntu 16.04
    • VNC Installation on Ubuntu
    • How to install XRDP in Amazon Linux 2
  • My issues
    • WordPress
      • WordPress FTP error
      • Unable to upload file to WordPress
      • WordPress Posts Returning 404 Error
      • How to Fix the 500 Internal Server Error on Your WordPress Website
      • How to Fix Corrupted Files and Databases in WordPress
      • Max_upload exceeded..!!! WordPress
      • 6 Ways To Increase the Maximum Upload File Size in WordPress
    • Being prompted for password after not setting one (RHEL/Amazon Linux)
    • Unable to transfer files from one instance to another using SCP
    • Website running and reachable via a browser however giving a 403 when running a CURL
    • Issue installing Cerbot on Amazon Linux 2
    • How to restore “Kernel panic – not syncing: VFS: Unable to mount root fs on unknown-block(0,0)”
    • Renewing your SSL certificate using Certbot/Letsencrypt manually:
  • AWS(Amazon Web Services)
    • Instance Health Checks failing
      • How to fix a Kernel panic – not syncing: VFS: Unable to mount root fs on unknown-block(0,0)
      • Reasons why an instance with root on LVM might fail to boot
      • Instance failing health checks with a Kernel Offset: disabled error
    • EC2 SSH ISSUES
      • Injecting userdata to allow ssh
    • Amazon EBS
    • AWS Workarounds
      • Steps to install python3.7 on Amazon Linux 1
      • Using userdata to resolve ssh issues to your EC2 instance
      • How to use the same SSH key pair in all AWS regions
      • Accidentally enabled UFW on your Ubuntu instance and cant SSH as a result?
    • Lightsail Loadbalancer failing health checks
    • AWS Docs
      • How can I avoid DNS resolution failures with EC2 Linux?
      • Extending a Linux File System after Resizing the Volume
    • Service Introduction Videos
      • What is AWS?
      • Introduction to Amazon EC2
      • Amazon Elastic Block Store (EBS) Overview
    • Troubleshooting videos
      • How do I recover access to my EC2 instances if I lost my SSH key pair?
      • How do I move my EC2 instance to another subnet, Availability Zone, VPC, or region?
  • Troubleshooting
    • Server A Can’t Talk to Server B
    • Troubleshoot Slow Networks
    • How To Troubleshoot Common Site Issues on a Linux Server
    • How to fix a Kernel panic – not syncing: VFS: Unable to mount root fs on unknown-block(0,0)
    • How to fix high memory usage in Linux ?
    • Troubleshooting a Linux kernel panic after patching
    • Reproducing a “Kernel panic – not syncing: VFS: Unable to mount root fs on unknown-block(0,0)”
  • Articles
    • How to get notified whenever someone logs in via SSH?
    • procSpy : Python tool that monitors and logs user-run commands on a Linux system
    • How to identify duplicate files on Linux
    • Power of SSH Tunneling
    • Linux commands you should never run on your system
  • Redis
    • ElastiCache
      • Redis restore from S3 snapshot fails
    • An introduction to Redis data types and abstractions
    • Redis – Commands
    • Redis – Keys
    • Redis – Strings
    • Redis – Hashes
    • Redis – Lists
    • Redis – Sets
    • Redis – Sorted Sets
  • My Curriculum Vitae (CV)
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Created by : Imraan Abrahams
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