Virtualbox CLI

List running vms in Virtualbox

 VBoxManage list runningvms  

Take VM snapshot

 VBoxManage snapshot centos702 take snap1-before-ldap 

Save VM State

 VBoxManage controlvm centos701 savestate 

Starting a VM

 VBoxManage startvm centos702 

Linux Foundation Certified System Administrator Domain and Competencies v.2.16

Domains and Competencies V2.16

ESSENTIAL COMMANDS - 25%

• Identify the component of the Linux distribution that a file belongs to
• Install Linux Distribution to physical media
• Install Linux Distribution over a network
• Install Linux Distribution into a virtual disk image
• Log into graphical and text mode consoles
• Search for files
• Evaluate and compare the basic file system features and options
• Compare text files
• Compare binary files
• Identify different types of files
• Create and edit text files
• Use input-output redirection (e.g. >, >>, |, 2>)
• Analyze text using basic regular expressions
• Access remote systems securely using CLI
• Archive, compress, unpack, and uncompress files
• Create, delete, copy, and move files and directories
• Create hard and soft links
• List, set, and change standard file permissions
• Read, and use system documentation
• Manipulate file content programmatically
• Transfer files securely via the network
• Manage access to the root account
• Perform disk image management
• Use version control tools
• Run commands on many systems simultaneously

Operation of Running Systems - 20%

• Boot, reboot, and shut down a system safely
• Boot systems into different runlevels manually
• Install, configure and troubleshoot the bootloader
• Manage shared libraries
• Change the priority of a process
• Identify resource utilization by process
• Locate and analyze system log files
• Schedule tasks to run at a set date and time
• Verify completion of scheduled jobs
• Manipulate Linux system during the boot process
• Manipulate Linux system during the recovery process
• Support incident management for outages/trouble
• Identify and resolve system performance bottlenecks and platform instability
• Update hardware to provide required functionality and security
• Update operating systems to provide required functionality and security
• Update software to provide required functionality and security
• Update the kernel and ensure the system is bootable
• Verify the integrity and availability of hardware
• Verify the integrity and availability of resources
• Verify the integrity and availability of key processes
• Change kernel runtime parameters, persistent and non-persistent
• Use scripting to automate system maintenance tasks
• Manage the startup process and services
• List and identify SELinux/AppArmor file and process contexts
• Produce and deliver reports on system use (processor, memory, disk, and network), outages, and user requests
• Update packages from the network, a remote repository, or from the local file system
• Configure and modify SELinux/AppArmor policies
• Monitor security and conduct audits
• Script automation tools to make work faster and more accurate
• Develop and test disaster recovery plans
• Maintain systems via configuration management tools
• Train team members on new technology or changes to existing systems
• Develop system disaster recovery tests
• Install software from source

User and Group Management - 15%

• Create, delete, and modify local user accounts
• Create, delete, and modify local groups and group memberships
• Manage system-wide environment profiles
• Configure a client to use LDAP for user and group information
• Configure a system to authenticate using Kerberos
• Configure set-GID directories for collaboration
• Manage template user environment
• Configure user resource limits
• Manage user processes
• Configure PAM

Networking - 15%

• Configure networking and hostname resolution statically or dynamically
• Configure network services to start automatically at boot
• Implement packet filtering
• Configure firewall settings
• Configure a system to perform Network Address Translation
• Start, stop, and check the status of network services
• Monitor network performance
• Statically route IP traffic
• Dynamically route IP traffic
• Synchronize time using other network peers
• Configure network traffic tunneling

Service Configuration - 10%

• Configure a basic DNS server
• Maintain a DNS zone
• Configure a caching-only name server
• Configure a caching-only name server to forward DNS queries
• Configure an FTP server
• Configure anonymous-only download on FTP servers
• Provide/configure network shares via NFS
• Provide/configure network shares via CIFS
• Configure an smtp service
• Restrict access to an smtp server
• Configure a mail transfer agent (MTA) to accept inbound email from other systems
• Configure an MTA to forward (relay) email through a smart host
• Configure email aliases
• Configure SSH servers and clients
• Configure SSH-based remote access using public/private key pairs
• Configure a DHCP server
• Configure the HTTP proxy server
• Restrict access to the HTTP proxy server
• Configure an HTTP client to automatically use a proxy server
• Configure an IMAP and IMAPS service
• Configure host-based and user-based security for a service
• Query and modify the behavior of system services at various run levels
• Configure direct-attach and network printers
• Configure an HTTP server
• Configure HTTP server log files
• Configure SSL with HTTP server
• Set up name-based virtual web hosts
• Deploy a basic web application
• Restrict access to a web page
• Configure time synchronization server
• Synchronize time using other time synchronization peers
• Configure a system to log to a remote system
• Configure a PXE Boot server
• Configure an LDAP server and schema 
• Configure a system to accept logging from a remote system
• Diagnose routine SELinux/AppArmor policy violations
• Configure SELinux/AppArmor to support a service
• Configure database server
• Configure SELinux/AppArmor to confine a service

Virtualization - 5%

• Configure a hypervisor to host virtual guests
• Install Linux systems as virtual guests
• Start, stop, modify the status of virtual machines
• Access a VM console
• Migrate a VM between two hosts
• Configure systems to launch virtual machines at boot
• Evaluate memory usage of virtual machines
• Create light-weight virtualized guests via namespaces
• Resize RAM or storage of VMs
• Cloning and replicating VMs using images or snapshots

Storage Management - 10%

• List, create, delete, and modify storage partitions
• Create, migrate, and remove Physical Volumes
• Assign Physical Volumes to Volume Groups
• Create, modify and delete Logical Volumes
• Extend existing Logical Volumes and filesystems
• Create and configure encrypted partitions
• Configure systems to mount file systems at or during boot
• Configure and manage swap space
• Add new partitions, and logical volumes
• Create, mount, and unmount standard Linux file systems
• Assemble partitions as RAID devices
• Identify storage devices using block device attributes
• Configure systems to mount standard, encrypted, and network file systems on demand
• Create and manage filesystem Access Control Lists (ACLs)
• Diagnose and correct file permission problems
• Setup user and group disk quotas for filesystems
• Restore default SELinux file contexts
• Manage Linux file system features and flags
• Configure remote block storage devices
• Design and test backup/recovery strategies
• Deploy, configure, and maintain high availability/clustering/replication

ref: https://training.linuxfoundation.org/upcoming-program-changes-for-the-lfcs-certification-exam

Virtualbox VM ping duplicate

Having this ping duplicate in VM on Virtualbox

 [root@centos701 ~]# ping 192.168.1.1  
 PING 192.168.1.1 (192.168.1.1) 56(84) bytes of data.  
 64 bytes from 192.168.1.1: icmp_seq=1 ttl=64 time=1.51 ms  
 64 bytes from 192.168.1.1: icmp_seq=1 ttl=63 time=1.56 ms (DUP!)  
 64 bytes from 192.168.1.1: icmp_seq=2 ttl=64 time=18.9 ms  
 64 bytes from 192.168.1.1: icmp_seq=2 ttl=63 time=18.9 ms (DUP!)  
 64 bytes from 192.168.1.1: icmp_seq=3 ttl=64 time=1.68 ms  
 64 bytes from 192.168.1.1: icmp_seq=3 ttl=63 time=1.75 ms (DUP!)  

Solution: Disable your host's IP forwarding

 [root@fedora ~]# sysctl -w net.ipv4.ip_forward=0<br />  
 net.ipv4.ip_forward = 0  

Referrence:

http://linuxconfig.org/virtualbox-ping-from-virtual-machine-results-in-dup-duplicate-packages