E115 Exam #1

Refers to all available components (wildcard)

*

Refers to the parent directory

../

Refers to the current directory

./

Absolute path name (E115 Locker)

/afs/eos.ncsu.edu/courses/e/e115

Absolute path name (Home)

/afs/unity.ncsu.edu/users/h/hmstewar

Connects two commands on the same line (called chaining)

;

File System hierarchy

A File System is a methodology by which data and information are stored on storage devices (hard drives, floppy disc, etc.), making them easily retrievable. root: The root of a file tree is the beginning of the file system, and all other nodes trace back to it. parent: Those with child nodes are known as parent nodes child: Nodes can have child nodes below them, but they do not have to leaf: Leaf nodes are nodes which have no children

Graphical User Interface

A GUI presents the user with a full graphical display (images, buttons, scrollbars, etc.). These systems allow the use of a mouse or some other pointing device to click, select, drag, and manipulate objects. Windows provides a GUI, and PuTTY can be downloaded to use this GUI to provide a CLI. Both Mac and Linux also use the GUI to provide a CLI. However, for these Operating Systems, the CLI is built in.

Botnet

A collection of computers that has been infected with a specialized virus, usually a worm. The worm can control any infected computers, which are then sometimes referred to as "zombies".

Rootkit

A more advanced version of a Trojan. In computer terms, "root" almost always means increased or unlimited control. When one of these gets into your computer, a hacker can do almost anything to your machine. It can also be extremely difficult to detect and remove.

Virus

A piece of software that can copy itself and spread, just like a biological virus. This is one of the oldest and most recognized computer security terms.

Keyloggers

A program that copies everything you type and saves it to a file or sends the data to the keylogger owner. Technically considered an advanced form of spyware. Normal security software might not be able to shut them down, but they are usually operated by someone in the household or legally by employers.

Backdoor

A secret entrance to your computer that lets someone bypass your security. These usually come from program flaws or are intentionally built in by the developer.

Zero-day exploit

A serious security flaw for which no fix exists. Hackers can find and use it before the developer can release a patch, because there is no fix.

Filing System

AFS

Worms

An advanced type of virus that replicates and spreads with little or no action on your part.

Kernel

At the core of an OS is a piece of software known as the kernel. It is a program that sits between the user interface and the hardware and manages many tasks that happen within the computer. Monolithic kernels provide these general services. Individual services are itemized below this list: Interfacing (System call API/Device driver API); File system and virtual file system; Process and task management; Scheduling; Memory management and virtual memory

Virtual Computing Lab

Easy-to-use remote access from one's own desktop or mobile computer Full access to a dedicated computing resource (some scheduling choices include monitored root or administrator access). This access is the same or more than what is possible in a physical computing laboratory. Vendor-standard remote access protocols and client software. Eliminates the need for specialized customization of one's own computer and eases updates and maintenance Extensible to any remotely-accessible desktop systems in specialized campus labs. Departments can bring their lab to their students. For more details or help using the VCL, visit http://vcl.ncsu.edu/help

File Transfer System

Expand drive

Phishing

Falsely claiming to be a legitimate company to scam the consumer

Spyware

Focused specifically on gathering information about you. Think: data mining.

Unity ID

Generally composed of first / middle initials and the first six letters of your last name; In cases where the Unity ID following this format is already in use, numerals will be placed in the 8th spot to create a unique ID. ; Other exceptions to the standard eight character format are middle names and short names. If a user does not have a middle name, the middle initial will be skipped, and the remainder of the rule is followed. If the user's last name is shorter than six characters, the entire last name is used and the Unity ID is allowed to be shorter than eight characters.

Trojan

Like the Trojan horse from Greek mythology, a computer Trojan looks like something trustworthy, but when you download it to your computer, it turns out to be malware. This can be done by hiding or misrepresenting a file extension.

Campus Submitting

Moodle wolfware.ncsu.edu

AFS File Tree

On the AFS file tree, all absolute path names begin with the forward slash.

Passwords (recommendations vs. requirements)

Password changes are made at http://sysnews.ncsu.edu/passwd/. Password change requests are processed every 5 minutes, so new password should be valid almost immediately. Your password must: be at least 8 characters; be no more than 100 characters; not contain ' (for Google logins); not contain your Unity ID; not contain your Unity ID backwards; contain at; least one digit (number); contain at least one letter; not contain a word found in the dictionary with three or more letters; not have 5 or more consecutive digits (ex.35127); be more than a simple case change of your old password It is recommended that your password: have at least one special character (not a number or letter); contain at least one capital letter; contain at least one lowercase letter

Ransomware

Sometimes also referred to as "Scareware", this type of malware spooks you into parting with actual money, and can take many forms. A common form is a fake anti-virus program that claims you have many viruses and must pay for the full version to get rid of them. Essentially, ransomware is considered any program that demands payment to give you your system back.

Text-based User Interface/Text Line Interface (TUI/TLI)

TUI/TLI displays using text only (usually with different colors) but allows for mouse input rather than relying on a command language. This interface was developed in the mid-late 1980's to run DOS programs. It is sometimes seen when users are in "safe mode" on some modern computers, but was quickly replaced by the GUI.

Student ID

The ID Number is a series of digits; Older Student ID numbers begin with 3 leading "0's", while newer Student ID Numbers begin with the "010" "2000", or some numerical sequence. Your Student ID is used for some courses, not E 115, and when you are registering for courses with your academic advisor. It is important that you understand the difference between these two items.

User Interfaces

The interface between the user and the computer determines the way that an individual interacts with a computer. Based on these different user interfaces, we can categorize operating systems into a few types: Terminal-based (Command Line Interface- CLI), Text-based (Text-based User Interface/Text Line Interface- TUI/TLI), Graphics-based (Graphical User Interface- GUI), or a Hybrid (mix of two or three).

Device Drivers

The kernel depends on individual pieces of software to control each individual piece of hardware, called device drivers. Device drivers contain instructions, like a manual for the kernel, on how to make the hardware perform a requested function. The OS calls the driver, and the driver "drives" the device. These software pieces exist for all hardware, and are often specialized for things like video cards, network adapters, input devices and sound cards.

Command Line Interface (CLI)

These Operating Systems work primarily through a command line (text input) via a keyboard and generally do not display graphics or utilize the mouse. These systems use a command language to tell the computer what actions to perform.

Drive-by download

When malware takes advantage of security flaws in your programs to download to your computer without your permission.

add

add [program] Adds the program specified by program to the current environment. Programs with a GUI component can only be used if X is enabled. The user can view a list of all available programs by typing add without a program name.

attach

attach [locker_name] Creates a shortcut to the course directory specified by locker_name. Shortcuts can then be referenced via the new, shorter pathname: /ncsu/locker_name.

cd

cd location Changes the current directory to the location specified by location.

cp

cp [-option] [old_location/]file_name new_location -r : recursive (this option is necessary in order to copy directories) Creates a copy of the file or directory with the name specified by file_name, and places it in new_location, leaving a copy in old_location. Multiple files and directories can be copied simultaneously, and each file_name should be separated by a space.

List Access

fs la [location] Displays the user access list for the directory specified by location. If no location is specified, the access list for the current directory is shown.

Mount a Backup

fs mkm BACKUP users.unityid.backup Mounts a backup with the name BACKUP (or whatever directory name the user wants to create) to the current directory. The backup contains the contents of the user's AFS space as it existed at midnight the previous night. **This command must be executed in the user's home directory.**

Remove a Backup

fs rmm BACKUP Removes a mounted directory named BACKUP. **This command must be executed in the user's home directory.**

Set Access

fs sa [location] [unityid] [access_list] Sets the user access list for the directory specified by location, granting the rights specified by access_list to unityid. A list of individual access rights are listed at the end of this document.

less

less [location/]file_name Displays the contents of a file with the extension .txt, .html, or .css directly in the terminal window. Use the ↑ and ↓ arrow keys to navigate, and press q to return to the main screen. more does less and less does more

ls

ls [-option] [location] -a : all (displays all files, including hidden files) -l : long (displays each file on a separate line with certain details) Displays a list of the files and directories located in location. If no location is specified, the contents of the current directory are shown.

man

man [-option] command Displays the usage information of a command and its features. Use the ↑ and ↓ arrow keys to navigate, and press q to return to the main screen.

mkdir

mkdir [location/]directory_name Creates a new directory with the name specified by directory_name. If no location is specified, the directory is placed in the user's current directory.

more

more [location/]file_name Displays the contents of a file with the extension .txt, .html, or .css directly in the terminal window. The user can navigate the document using the spacebar. more does less and less does more

mv

mv [old_location/]old_file_name [new_location/][new_file_name] Moves the file with the name specified by old_file_name, and places it in new_location with the name specified by new_file_name. If no new_file_name is specified, the file will keep the same name. If no locations are specified. The file will simply be renamed. Multiple files can be moved simultaneously. You can only move a file from a directory you have permissions to ALSO RENAMING CAN BE DONE BY THIS COMMAND.

Campus E-mail

o Fields: Required Fields: To: - Enter mail address of the person(s) to whom you are sending the message. Enter as many addresses as you like, usually separated by commas Recommended Fields (Required for all E115 correspondence): Subject: - Enter a relevant heading that accurately describes the message contents. Optional Fields: CC: - Carbon Copy. To send others a copy of the mail, enter their email addresses here. BCC: - Blind Carbon Copy. To send others a copy of the mail without the recipients in the To: or Cc: fields knowing about it, enter their email addresses here. o Appropriate use: For example, your NCSU email will be used only for University communications and email from professors, and your personal account will be used for subscribing to forums, online newsletters, Facebook, etc. When emailing an instructor or grader, the subject should have the course number, section number, and a brief description of the email contents. For a student in section 12 asking about homework 5, the subject could look like E115-012, Homework 5 Question.

Accessing AFS

o Must know how to login & use Putty (Windows students) : remote-linux.eos.ncsu.edu o Must know how to ssh in terminal (Mac students) : ssh -X [email protected] o Must know how to use ExpanDrive (or FTS equivalent) K: drive ; To modify your storage settings: 1. Visit http://sysnews.ncsu.edu 2. Under the User Info section on the top left of the page, log in using your Unity account information 3. Once logged in, click on the Quota Manager link 4. Enter the amount of available storage space for each location and click the Submit Change Request button > Nightly backup of user storage spaces

Absolute vs. Relative path names

o Must know your home directory (absolute & relative): o Must know the E 115 course locker (absolute) An absolute path name always begins with the root and relative path names never begin with the root; Relative path names are dependent on your current location within the file tree

Unity Accounts

o Resources: o Passwords - recommendations vs. requirements:

Campus Printing

print.ncsu.edu ; paper cut only PDF's from web print ; any document from a campus computer; Networked printing, see http://print.ncsu.edu ; This new system allows users to pay for printing using their "AllCampus" accounts and rollover from the old "Print Quota" system.

pwd

pwd Displays the absolute pathname to the user's current directory. Where am I?

quota

quota Displays information about the AFS space of the current user. This command is run by default at the beginning of each session.

Access Control List

r : read (The user can view and copy the contents of files in the directory) l : look (The user can see the contents of the directory_ i : insert (The user can create or move files into the directory) d : delete (The user can delete files from the directory) w : write (The user can make changes to files in the directory) k : lock (The user can set advisory locks in the directory) a : admin (The user can set permissions for the directory) all : (Gives the user all rights to the directory) none : (Removes all rights for the user from the directory)

rm

rm [-option] [location/]file_name -r :recursive (this option is necessary in order to delete directories) -f : forced (deletes files and directories without asking permission) Deletes the file or directory specified by file_name.

script

script [-option] [location/]file_name.txt -a : append (allows the user to append the log file to an existing file) -f : flushed (outputs contents to file as commands are entered) Creates a log file with the name specified by file_name.txt to record all terminal input and output from the time the command is invoked until the user types exit.

Terminal Connection Information

ssh -X [email protected]

unzip

unzip [location/]file_name.zip Extracts files that are located within file_name.zip so that the user can access them. Original .zip file remains in the directory and files are extracted into the same location as the .zip file.

zip

zip [-option] zipfile_name file_list -r :recursive (this option is necessary in order to zip directories) Places the files in file_list in the zip file specified by zipfile_name.

Refers to the home directory

~/