CompTIA Linux+ xk0-005

data · 18 Apr 2024

System Management

1.1 Summarize Linux fundamentals

Filesystem Hierarchy Standars(FHS)
- /boot
- /proc
- /sys
- /var
- /usr
- /lib
- /dev
- /etc
- /opt
- /bin
- /sbin
- /home
- /media
- /mnt
- /root
- /tmp
Basic boot process
- Basic input/output system(BIOS)
- Unified Extensible Firmware Interface(UEFI)
- Commands
  - mkinitrd
  - grub2-install
  - grub2-mkconfig
  - grub2-update
  - dracut
- initrd.img
- vmlinuz
- Grand Unified Bootloader version 2(GRUB2)
- Boot sources
  - Preboot eXecution Environment(PXE)
  - Booting from Universal Serial Bus(USB)
  - Booting from ISO
Kernal panic
Device types in /dev
- Block devices
- Character devices
- Special character devices
  - /dev/null
  - /dev/zero
  - dev/urandom
Basic package compilation from source
- ./configure
- make
- make install
Storage concepts
- File storage
- Block storage
- Object storage
- Partition type
  - Master boot record(MBR)
  - GUID[globally unique identifier] Partition Table (GPT)
- Filesystem in Userspace(FUSE)
- Redundant Arrey of Independant (or inexpensive) Disk(RAID) levels
  - Striping
  - Mirroring
  - Parity
Listing hardware information
- lspci
- lsusb
- dmidecode

1.2 Given a scenario, manage files and directories

File editing
- sed
- awk
- printf
- nano
- vi(m)
File compression, archiving, and backup
- gzip
- bzip2
- zip
- tar
- xz
- cpio
- dd
File metadata
- stat
- file
Soft and hard links
Copying files between systems
- rsync
- scp
- nc
File and directory operations
- mv
- cp
- mkdir
- rmdir
- ls
- pwd
- rm
- cd
- .
- ..
- ~
- tree
- cat
- touch

1.3 Given a scenario, configure and manage store using the appropriate tools

Disk partitioning
- Commands
  - fdisk
  - parted
  - partprobe
Mounting local and remote devices
- systemd.mount
- /etc/fstab
- mount
- Linux Unified Key Setup (LUKS)
- External devices
Filesystem management
- XFS tools
- Ext4 tools
- Btrfs tools
Monitoring storage space and disk usage
- df
- du
Creating and modifying volumes using Logical Volume Manager(LVM)
- pvs
- vgs
- lvs
- lvchange
- lvcreate
- vgcreate
- lvresize
- pvcreate
- vgextend
Inspecting RAID implementations
- mdadm
- /proc/mdstat
Storage area network (SAN)/network-attached storage(NAS)
- multipathd
- Network filesystems
  - Network File System(NFS)
  - Server Message Block(SMB)/Common Internet File System(CIFS)
Storage hardware
- lsscsi
- lsblk
- fcstat

1.4 Given a scenario, configure and use the appropriate processes and services

System service
- systemctl
  - stop
  - start
  - restart
  - status
  - enable
  - disable
  - mask
Scheduling services
- cron
- crontab
- at
Process management
- Kill signals
  - SIGTERM
  - SIGKILL
  - SIGHUP
- Listing processes and open files
  - top
  - ps
  - lsof
  - htop
- Setting priorities
  - nice
  - renice
- Process states
  - Zombie
  - Sleeping
  - Running
  - Stopped
- Job control
  - bg
  - fg
  - jobs
  - Ctrl+Z
  - Ctrl+C
  - Ctrl+D
- pgrep
- pkill
- pidof

1.5 Given a scenario, use the appropriate networking tools or configuration files

interface management
- iproute2 tools
  - ip
  - ss
- NetworkManager
  - nmcli
- net-tools
  - ifconfig
  - ifcfg
  - hostname
  - arp
  - route
- /etc/sysconfig/network-scripts/
Name resolution
- nsswitch
- /etc/resolv.conf
- systemd
  - hostnamectl
  - resolvectl
- Bind-utils
  - dig
  - nslookup
  - host
- WHOI
Network monitor
- tcpdump
- wireshark/tshark
- netstat
- traceroute
- ping
- mtr
Remote networking tools
- Secure Shell(SSH)
- cURL
- wget
- nc
- rsync
- Secure Copy Protocol(SCP)
- SSH File Transfer Protocol(SFTP)

1.6 Given a scenario, build and install software

Package management
- DNF
- YUM
- APT
- RPM
- dpkg
- ZYpp
Sandboxed applications
- snapd
- Flatpak
- AppImage
System updates
- Kernel updates
- Package updates

1.7 Given a scenario, manage software configurations

Updating configurations files
- Procedures
  - Restart service
  - Reload service
- .rpmnew
- .rpmsave
- Repository configuration files
  - /etc/apt.conf
  - /etc/yum.conf
  - /etc/dnf/dnf.conf
  - /etc/yum.repo.d
  - /etc/apt/source.list.d
Configure kernel options
- Parameters
  - sysctl
  - /etc/sysctl.conf
- Modules
  - lsmod
  - rmmod
  - insmod
  - modprobe
  - modinfo
COnfigure common system services
- SSH
- Network Time Protocol(NTP)
- Syslog
- chrony
Localization
- timedatectl
- localectl

2.0 Security

2.1 Summarize the purpose and use of security best practices in a linux environment

Managing public key infrastructure(PKI) certificates
- Public key
- Private key
- Self-signed certificate
- Digital signature
- Wildcard certificate
- Hashing
- Certificate authorities
Certificate use cases
- Secure Sockets Layer(SSL)/Transport Layer Security(TLS)
- Certificate authorities
- Encryption
Authentication
- Tokens
- Multifactor authentication(MFA)
- Pluggable authentication modules(PAM)
- System Security Services Daemon(SSSD)
- Lightweight Directory Access Protocol(LDAP)
- Single sign-on(SSO)
Linux hardening
- Security scanning
- Secure boot
  - UEFI
- System logging configurations
- Setting default umask
- Disabling/removing insecure services
- Enforcing password strength
- Removing unused packages
- Tunning kernel parameters
- Securing service accounts
- Configuring the host firewall

2.2 Given a scenario, implement identity management

Account creation and deletion
- Utilities
  - useradd
  - groupadd
  - userdel
  - groupdel
  - usermod
  - groupmod
  - id
  - who
  - w
- Default shell
- Configuration files
  - /etc/passwd
  - /etc/group
  - /etc/shadow
  - /etc/profile
  - /etc/skel
  - .bash_profile
  - .bashrc
- Account management
  - passwd
  - chage
  - pam_tally2
  - faillock
  - /etc/login.defs

2.3 Given a scenario, implement and configure firewalls

Firewall use cases
- Open and close ports
- Check current configuration
- Enable/disable Internet protocol(IP) forwarding
Common firewall technologies
- firewalld
- iptables
- nftables
- Uncomplicated firewall(UFW)
Key firewall features
- Zones
- Services
- Stateful
- Stateless

2.4 Given a scenario, configure and execute remote connectivity for system management

SSH
- Configuration files
  - /etc/ssh/sshd_config
  - /etc/ssh/ssh_config
  - ~/.ssh/known_hosts
  - ~/.ssh/authorized_keys
  - ~/.ssh/config
- Commands
  - ssh-keygen
  - ssh-copy-id
  - ssh-add
- Tunneling
  - X11 forwarding
  - Port forwarding
  - Dynamic forwarding
Executing commands as another user
- /etc/sudoers
- PolicyKit rules
- Commands
  - sudo
  - visudo
  - su -
  - pkexec

2.5 Given a scenario, apply the appropriate access controls

File permissions
- Access control list(ACL)
- Set user ID(SUID)
- Set group ID(SGID)
- Sticky bit
Security-enhanced Linux(SELinux)
- Context permissions
- Labels
  - Autorelabel
- System booleans
- States
  - Enforcing
  - Permissive
  - Disabled
- Policy types
  - Targeted
  - Minimum
- AppArmor
  - Application permissions
- Command-line utilities
  - chown
  - umask
  - chmod
  - getfacl
  - setfacl
  - ls
  - setenforce
  - getenforce
  - chattr
  - lsattr
  - chgrp
  - setsebool
  - getsebool
  - chcon
  - restorecon
  - semanage
  - audit2allow

3.0 Scripting, Containers, and Automation

3.1 Given a scenario, create simple shell scripts to automate common tasks

Shell script elements
- Loops
  - while
  - for
  - until
- Conditionals
  - if
  - switch/case
- Shell parameter expansion
  - Globbing
  - Brace expansions
- Comparisons
  - Arithmetic
  - String
  - Bollean
- Variables
- Search and replace
- Regular expressions
- Standard stream redirection
  - >
  - >>
  - <
  - «
  - &
  - &&
  - Redirecting
    - stderr
    - stdout
- Here documents
- Exit codes
- Shell built-in commands
  - read
  - echo
  - source
Common script utilities
- awk
- sed
- findd
- xargs
- grep
- egrep
- tee
- wc
- cut
- tr
- head
- tail
Environment variables
- $PATH
- $SHELL
- $?
Relative and absolute paths

3.2 Given a scenario, perform basic container operations

Container management
- Starting/stopping
- Inspecting
- Listing
- Deploying existing images
- Connecting to containers
- Logging
- Exposing ports
Container image operations
- build
- push
- pull
- list
- rmi

3.3 Given a scenario, perform basic version control using Git

clone
push
pull
commit
add
checkout
branch
tag
gitignore

3.4 Summarize common infrastructure as code technologies

File formats
- YAML Ain’t Markup Language (YAML)
- JavaScript Object Notation(JSON)
Utilities
- AnsiblePuppet
- Chef
- SaltStack
- Terraform
Continuous integration/continuous deployment(CI/CD)
- Use cases
Advanced Git topics
- merge
- rebase
- Pull requests

3.5 Summarize container, cloud, and orchestration concepts

Kubernetes benefits and application use cases
- Pods
- Sidecars
- Ambassador containers
Single-node, multicontainer use cases
- Compose
Container persistent storage
Container networks
- Overlay networks
- Bridging
- Network address translation(NAT)
- Host
Service mesh
Bootstrapping
- Cloud-init
Container registries

4.0 Troubleshooting

4.1 Given a scenario, analyze and troubleshoot storage issues

High latency
- Input/output(I/0) wait
Low throughput
Input/output operations per second(IOPS) scenarios
- Low IOPS
Capacity issues
- Low disk space
- Inode exhaustion
Filesystem issues
- Corruption
- Mismatch
I/O scheduler

4.2 Given a scenario, analyze and troubleshoot network resource issues

Network configuration issues
- Subnet
- Routing
Firewall issues
Interface errors
- Dropped packets
- Collisions
- Link status
Bandwidth limitations
- High latency
Name resolution issues
- Domain Name System(DNS)
Testing remote systems
- Nmap
- openssl s_client

4.3 Given a scenario, analyze and troubleshoot central processing unit(CPU) and memory issues

Runaway processes
Zombie processes
High CPU utilization
High load average
High run queues
CPU times
- steal
- user
- system
- idle
- iowait
CPU process priorities
- nice
- renice
Memory exhaustion
- Free memory vs. file cache
Out of memory(OOM)
- Memory leaks
- Process killer
Swapping
Hardware
- lscpu
- lsmem
- /proc/cpuinfo
- /proc/meminfo

4.4 Given a scenario, analyze and troubleshoot user access and file permissions

User login issues
User file access issues
- Group
- Context
- Permission
- ACL
- Attribute
- Policy/non-policy
Password issues
Privilege elevation
Quota issues

4.5 Given a scenario, use systemd to diagnose and resolve common problems with a Linux system

Unit files
- Service
  - Networking services
  - ExecStart/ExecStop
  - Before/after
  - Type
  - User
  - Requires/wants
- Timer
  - OnCalendar
  - OnBootSec
  - Unit
  - Time expressions
- Mount
  - Naming conventions
  - What
  - Where
  - Type
  - Options
- Target
  - Default
  - Multiuser
  - Network-online
  - Graphical
Common problems
- Name resolution failure
- Application crash
- Time-zone configuration
- Boot issues
- Journal issues
- Services not starting on time

Reference

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