CPSC4240 Midterm 2

What is the kernel?

the modular main component of the OS that provides an interface between hardware and processes

What is a monolithic kernel?

a type of kernel in which all modules run in the kernel space

What is a microkernel?

runs minimum resources possible; has a small kernel space and a large user space

What type of kernel is a Linux kernel?

monolithic

What does "uname -r" display?

the kernel release version

What makes up kernel version names?

MAJOR.MINOR.PATCH

When is the MAJOR incremented on the kernel version?

when you make incompatible API changes

When is the MINOR incremented on the kernel version?

when you add functionality in a backwards compatible manner

When is the PATCH incremented on the kernel version?

when you make backwards compatible bug fixes

What does BSOD stand for?

blue screen of death (windows)

What is a device driver?

software that talks to the devices/software that handles controllers for attached hardware

acts as an interface between OS and devices

Is the device driver part of the kernel or independent of it?

independent of it in terms of development

Is the device driver part of the user space or kernel space?

kernel space

What directory do devices live in?

/dev

Where can you find a list of character and block devices?

/proc/devices

Where can you find files that expose device details?

/sys/devices

What are hotpluggable devices?

devices that can be physically added or removed without a reboot

What are coldpluggable devices?

devices that when physically added or removed, require a reboot

What is udev?

a function of systemd that acts as a device manager that automatically detects hardware devices

What are the "major numbers" associated with a device?

ids the driver with which the file is associated (type of device)

What are the "minor numbers" associated with a device?

ids an instance of a given device type (unit number)

What are pseudo-devices?

phantom device drivers that control no actual device

If we list what's in the /dev directory, what do we see?

list of pseudo devices, the hard drive and partitions

What are examples of pseudo devices?

/dev/null, /dev/zero, /dev/urandom

What does /dev/null do?

black hole that discards everything written to it, produces no output

What does /dev/zero do?

accepts and discards input, output is continuous zero bytes

What does /dev/urandom do?

pseudo-random number generator

What does this command do and when do you need to use it? "mknod filename type major minor"

creates a device file because sometimes you have to

What are the four types of kernel failures?

soft lockup, hard lockup, panics, linux "oops"

What is nvme?

non-volatile memory express is a storage protocol for SSDs

What is a block device driver?

read or written one block at a time

What is a character device driver?

read or written one byte at a time

What is an example of a block device?

SATA drive

What is an example of a character device?

/dev/tty (terminal device), /dev/null

What is a soft link?

a symbolic link that acts as a shortcut as it points to a filename and does not contain data on the file

What is a hard link?

a direct reference to an inode that contains a copy of the original file

What's the difference between soft and hard links?

hard links are a direct link, whereas soft links have an extra layer of reference

What is an inode?

a data structure that describes a filesystem object as it contains the metadata of a file

How does the file permissions tell you if there's a link?

there will be an "l" at the beginning of the permissions string

What kind of link does the file permission string tell you about?

it only tells you if there's a soft link, will not appear for hard links

Who assigns the inode numbers?

the kernel

How do you display the inode number?

ls -l

What does ls -t do?

shows files in order of timestamp

How do you create a softlink?

ln -s somefile_name softlink_name

How do you create a hard link?

ln somefile_name hardlink_name

What happens when you mount something over your files?

it hides your files, but does not delete them

Can you see your files again after unmounting what's covering them, or are they gone?

yes

What directories can you mount on?

mnt, cdrom

What is stuxnet?

a computer virus that was used to target a Iranian nuclear facility

What is a zero day exploit?

a security flaw that is exploited that was previously unknown

Who is responsible for the security of the organization?

system admin

What is the weakest link in the system and why?

humans because of their emotions, can be easily exploited, and can be predictable and lazy

What does it mean to have defense and depth security?

multiple levels of security that you have to overcome

What is an attack surface?

anything that you can find out about someone's system without actually hacking in

What is operation security?

not letting anyone know what you're doing

What is a grey man?

a type of security that doesn't let you know it's there (utilizes the concept of hiding in plain sight)

What does USA PATRIOT Act stand for?

The Uniting and Strengthening America by Providing Appropriate Tools Required to Intercept and Obstruct Terrorism Act of 2001

What does the USA PATRIOT Act do?

allows for the government to expand their surveillance to prevent terrorism (also expanded the definition of terrorism)

When did Edward Snowden whistleblowing happen?

2015

What is the CIA triad of cybersecurity?

confidentiality, integrity, and accessibility

What is biometrics?

using your personal biological data as an identifier because it's almost always unique to you (exception = twins)

What are some examples of biometrics?

eye scan, finger print

What is cryptography?

allows people to communicate secretly even on unsecure channels

What is symmetric cryptography?

sender and receiver share a common key to encrypt and decrypt

What is asymmetric cryptography?

shared public key and secret private key

What is stegonography?

the method of hiding data in another media type so that the very existence of the data is concealed

What type of security is steganography?

security through obscurity

What are the components of steganography?

carrier, payload, stegomedium

Who rotates logs?

cron

What are some facts about SATA drives?

What kind of device can be added and removed that require a reboot?

coldpluggable

What kind of device can be added and removed without a reboot?

hotpluggable

What are phantom device drivers called?

pseudo device drivers

What do phantom device drivers control?

they don't control actual devices

What command allows you to list all hard drive partitions?

lsblk

What is kernel panic?

kernel enters and unknown state and then panics, which leaded to a reboot or error message

What are the three categories of crimes involving computers?

computer-assisted, computer targeted, and computer incidental