Introduction To Linux Flashcards
What does Unix refer to?
Linux and “Linux-like” operating systems
Why are Linux systems the most common target for attackers
96.3% of the top one million web servers are running Linux
What is FOSS
Free Open Source Software
What is a Distribution (Distro)
Special-purpose variants of the operating system
Who is the Ubuntu distro geared towards
General-purpose users
Who is the Kali Linux distro geared towards
Specifically designed for security professionals
Command-line only machines are called
Headless servers
Which distro is best suited for a Central Data Server
Fedora and CentOS
Which distro is best suited for a Public Web Server
Ubuntu and Fedora
Which distro is best suited for an IT Audit Workstation
Kali Linux
Which distro is best suited for a User Workstation
Ubuntu
What is SELinux
SELinux has a built-in file permission security enhancement developed by the NSA
CentOS and Fedora have it implemented by default
Which version of Ubuntu Servers do you choose if you are looking for a version that will remain stable over time?
LTS version
‘Long Term Support’s
The LTS version will remain stable and only change appropriately once a year
What is the Linux directory that contains every other folder
/ (root)
What is the directory that contains the user’s private files
/home
(Users should not be able to save files elsewhere)
What directory contains configuration files
/etc (pronounced ‘etsy’)
Configuration files, define how a machine runs and who can use it
Which directory contains main Binary or Program files?
/bin and /sbin
Bin for user programs
Sbin for admin programs
What directory contains files that change over time
/var
Which directory contains files that are only needed for a short period of time
/tmp
What is a Process
A running program is called a process
When a program runs, it must process data and potentially make changes to the file system. This is why a running program is called a process
When these programs process, save and modify data, they consume a computer’s resources.
What is Memory
The space used by a process to save and manipulate data
What 2 forms does memory come in?
1) RAM (Random Access Memory) : Used to run the program’s code. RAM is only used while the program is running.
The more work a process does, the more RAM it needs.
2) Disk Space: used to save data permanently
Files saved to a disk persist even after a process ends
What is the role of the CPU?
The Central Processing Unit acts as the brain of the system, determining how much work a process has to do, and how difficult that work is.
What is a DoS attack doing?
Denial of Service Attacks - attackers perform a DoS attack by launching processes that eat up memory on a target machine.
This can slow down or crash the machine, making it unavailable to the users, thus denying them service
Command to see all running processes in real time?
top
(Table of processes)
While in top
u(filter mode by username or PID)
P (sort by CPU usage)
M (sort by MEM usage)
z (Add cool visual colours)
x (Highlight column you are currently sorting by)
How do you take a snapshot of all the running process on the system
ps command
(Different arguments allow you to show different subsets of processes and use this output with other commands)
Command to Stop a Process
kill
(Used to stop a process, usually ones causing problems. kill attempts to allow a process to finish before it shuts it down)
What is Dynamic Analysis
The process of running a potentially malicious script and monitoring it’s effects.
What are PPAs
Repositories specifically used to store and distribute packages are known as Personal Package Archives or PPAs
