RHCSA – EX 200 Study Guide | Stuff that a middle age man is still learning

This was last updated on 1/2/2021.

Installation
- Kickstart – Automate installs
  - A kickstart file is an instruction file on how to install the operating system
  - Included instruction for
    - Creating partitions
    - Creating Users
    - Preparing network settings
    - Installing software
  - When an install is completed a kickstart file is saved to /root reflecting all settings used.
    - anaconda-ks.cfg
  - Delivery methods
    - HTTP server
    - FTP server
    - ramdisk
  - Unattended commands
    - sudo virt-install
    - –name centos-ks
    - –ram 2048
    - –disk path=[path],format=[format],size=[size of disk]
    - –location=[path of ISO]
    - –nographics
    - –intrd-inject=[kickstart file path]
    - –extra-args=[?file path] ip=[dhcp/other options] console=tty0 console= ttyS0,1152008n8″
    - –os-variant=
Understand and use essential tools
- handling files
  - Create
  - Edit
  - Archive and compress files
    - tar
    - star
    - gzip
    - bzip2
- Directories
  - Create
  - Delete
  - Copy
  - Move
- Command-line environments
  - Input-Output Redirection
    - >, >>, |, 2>, etc..
  - File Management
- Documentation
  - Locate, read and use system documentation
    - Man
    - Info
    - /usr/share/doc
- Schedule recurring tasks
- Access a shell prompt
- Issue commands with correct syntax
- Grep and regular expressions
- Access remote systems using SSH
- Create hard and soft links
Create simple shell scripts
- BASH
- Python
- Lua
- Tcl
- Ruby
Operate running systems, including
- booting into different run levels
  - Different targets manually
- identifying/Manage processes
  - Intensive processes
  - kill process
- starting and stopping services and virtual machines
  - Network services
- Controlling services
- Interrupt the boot process to gain access
- Locate and interpret/Read log files and journals
- Boot, reboot, and shut down a system normally
- Process scheduling
- Manage tuning profiles
- Save system journals
- Transfer files between systems
- Virtualization
  - KVM – Kernal-based Virtual Machine
    - Used to host guest machines/Hypervisor
    - Provides
      - Overcommitting of physical resources
        
        HDD
        
        CPU
        
        RAM Memory
      - Agent on the guest to communicate with the hypervisor
      - Disk I/O throttling
      - Virtual CPU hot add
      - Nested virtualization (not recommended of production)
    - Multiple types of devices
      - Differnt types of devices can appear in multiple categories with different benefits and downsides.
      - Virtualized
        
        CPU
        
        Supports 240 virtual CPUs
        
        Passes CPU instruction to host CPU
        
        CPU instruction run at full speed in guest
      - Paravirtualized (Fast)
        
        Device Types
        
        Network Cards (virtio-net)
        
        Block device (virtio-blk)
        
        Controller device (virtio-scsi)
        
        Serial device (virtio-serial)
        
        Graphics card (QXL)
        
        Devices talk directly to the hypervisor using hyper calls
        
        Requires paravirtualized drives for the device(s)
      - Emulated (Slow)
        
        Look like real devices in VM but are virtualized in software
        
        Type of devices (A sample of the device but there are more see the official documentation for full list)
        
        Host PCI bridge
        
        PS/2 mouse and keyboard
        
        USB graphics tablet
        
        USB controller and USB hub
        
        Serial ports
        
        IDE block device
        
        Floppy disk device
        
        HDA sound device
        
        Logic PCI video card
        
        Network adapter
      - Shared (passthrough/Physically shared)
        
        No other machine will have access to the device if passed through
        
        Type of devices
        
        USB
        
        PCI
        
        SCSI
        
        PCI Express function passthrough
        
        Cards that have multiple functions such as SCSI and USB could be passed to different VM devices
      - Storage Resource Pools
        
        Pools are comprised of
        
        Local nonshared disks
        
        Remote shared disks
        
        VM migration requires remote shared storage
        
        This is used if OS are wanted or needed to be migrated on the fly.
  - QEMU – Quick Emulator
    - Used to emulate virtual devices
  - Virtualization Management Tools
    - Management tools do not need to reside on the device that the virtual hosts are running on.
    - virt-manager
      - A graphical tool for managing virtual machines.
    - virsh (CLI)
      - Management and control hypervisors and virtual machines for the command line.
    - libvirt
      - Server and host side libraries used for interacting with hypervisor and host systems.
      - Uses API to monitor and manage:
        
        Virtual CPUs
        
        VM Memory
        
        Virtual storage
        
        Virtual networking
    - libvirt-client
      - Provides the client side libraries for access libvirt servers and includes virsh
    - Virtual Machine Manager (GUI)
    - virt-install
      - Used for command-line installation
    - qemu-kvm
      - Provides the user level kvm emulator
      - Facilitates communication between host and guest virtual machines
  - Install application
    - sudo yum install qeum-kvm libvirt virt-manager libvirt-client
    - Install by group
      - sudo yum install “Virtualization Client”
        
        gnome-boxes
        
        virt-install
        
        virt manager
        
        virt-top
        
        virt-viewer
        
        quem image
        
        libvirt
        
        libvirt-client
        
        libvert-python
        
        Dependencies
  - Start service and make it persistent
    - sudo systemctl start libvirtd
    - sudo systemctl enable libvirtd
  - Create a new Virtual Machine
    - Virtual Machine Manager
      - Applicaation>System Tools>Virtual Machine Manger
      - Click the “Create a new virtual machine” icon
        
        Or File>New Virtual Machine
      - Choose how to install OS
        
        Local
        
        Using this option for this example
        
        Network
        
        Network Boot
        
        Import existing disk image
      - Browse for image
      - Set Memory and CPU(s)
      - Set disk image size
      - Set Name choose a network.
Configure
- Local storage
  - Physical volumes
    - Create
    - Delete/Remove
    - Assign to volume groups
  - Partitions
    - Create
    - Delete
- Logical volumes management
  - Create
  - Delete
- Networking
- Bootup/modify bootloader
- List, create, delete partitions
  - MBR
  - GPT
- Mount file systems at boot
  - Universally unique ID (UUID)
  - Label
- Swap to a system non-destructively
Create and configure
- file systems and file system attributes, such as
  - permissions
    - List, set and change ugo/rwx permissions
    - Diagnose and correct problems
  - Encryption
    - C2R
      - grub- crypt –sha-512
  - Compression
  - Manage layered storage
  - Access control lists
  - Network file systems
    - Mount and unmount
    - NFS
  - Securely transfer files
  - Create and configure
    - Format
    - Mount
    - Unmount
    - File system types
      - vfat
      - ext4
      - xfs
  - Manage SUID, SGID and sticky bits
  - Set-GID directories for collaboration
    - Create
    - Configure
  - Extend existing logical volumes
Deploy, configure, and maintain systems
- Software
  - Installation
  - Updates
  - Redhat network, remote repository or local file system
  - Work with package module streams
- Core services/kernel packages
- Linux system Virtual guests
  - Access virtual machine’s console
  - Start/stop virtual machines
- CRON
  - Scheduling task
- Start/stop services
  - Start service at boot
- Boot into a specific target automatically
  - Modify the system bootloader
- NTP
Manage users and groups
- Create
- Delete
- Modify
- Local Groups and group memberships
  - Create
  - Delete
  - Modify
- Password/password aging
- Use Authentication Systems
- Log in and switch users in the multiuser target
- SuperUser access
Manage
- Security
  - Firewall
  - Key-based authentication for SSH
  - File access control lists
- SELinux configuration
  - Modes
    - Enforcing
    - permissive
  - Security Context
    - Restore Default
  - Modify Booleans
  - Diagnose and address routine policy violations
  - List/identify SELinux file and process context
- Basic networking
  - IPv4 and IPv6
  - Hostname resolution/DNS
  - Start automatically at boot
- Restore default file contexts
Perform basic container management