033 lab 2 kho tài liệu training

Lab Goal: Become familiar with file permissions and modification commands System Setup: A working installed Centos Linux LAB Instructions: PART 1: 1- Login to the system as user "root" 2- Run the command "cd " "cd" 3- Run the command "pwd" to print your work directory "pwd" You should see the output result /root 4- Run the command "cat /etc/passwd" and check the last lines "cat /etc/passwd" you should see the output result jamal:x:500:500::/home/jamal:/bin/bash tork:x:501:501::/home/tork:/bin/bash omar:x:502:502::/home/omar:/bin/bash student:x:503:504::/home/student:/bin/bash udemy:x:504:505::/home/udemy:/bin/bash mostafa:x:505:506::/home/mostafa:/bin/bash What is ":x:" ? 5- Add a new user using the "adduser" command "adduser ali" 6- Display the "/etc/passwd" contents again "cat /etc/passwd" Check the last line !! 7- Display the "/etc/shadow" contents "cat /etc/shadow" and check the last line , you should see mostafa:!!:16072:0:99999:7::: why there's no password in the nd field and what does 99999 refers to ? 8- Set password "typo100" for user "ali" "passwd ali" 9- Display the "/etc/shadow" contents "cat /etc/shadow" and check the last line again , you see the encrypted password for user "ali" ? 10Edit "/etc/login.defs" "vi /etc/login.defs" Change " PASS_MAX_DAYS" value to "72" then save and exit the file , what "PASS_MAX_DAYS" ? 11Delete user "ali" "userdel ali" 12Change your working directory "cd /home" 13Run the "ls" command to display user's home directories "ls" Why the user "ali" home directory still exists if we deleted the user "ali" using the "userdel" command ? 14Remove ali's home directory using the "rm" command (self assignment) 15To delete the user and his home directory run the "userdel –r" "userdel –r student" 16Run the "ls" command to display user's home directories "ls" Is student's home directory exist ? 17Run the command "chage –l tork" to display information about this user "chage –l tork" The result output will be something like Last password change : Dec 21, 2013 Password expires : never Password inactive : never Account expires : never Minimum number of days between password change Maximum number of days between password change Number of days of warning before password expires :0 : 99999 :7 18Change the Minimum number between password change by running the command "chage" "chage –m tork" 19Run the command "chage –l tork" again "chage –l tork" What's the Minimum number of days between password change now ? 20Change the maximum number of days between password change & number of days of warning before password expire for user "tork" (self assignment) 21Run the "chage –l tork" command after you finishing your modification "chage –l tork" 22Display the "/etc/group" file content and check the last lines "cat /etc/group" You should see udemy:x:505: mostafa:x:506: Note that when you create a new user to the system , a group created automatically for this user with the same username 23Add two groups to the system "groupadd sales" "groupadd it" 24Display "/etc/group" file content and check the last lines "cat /etc/group" Do you see the new groups you added to the system ? what is the groups IDs? 25Display user id and groups for a user "id tork" You should see uid=501(tork) gid=501(tork) groups=501(tork) Note that user tork is in the group "tork" 26Add user "tork" to the group "sales" "usermod -aG sales tork" 27Run the "id" command to display user "tork" uid and groups "id tork" You should see uid=501(tork) gid=501(tork) groups=501(tork),503(sales) 28Delete group "sales"" "groupdel sales" 29Run the "id tork" and check if user tork still member in the group "sales" or not "id tork" PART 2: 1- Change your current work directory "cd /home" 2- Create a new directory "shared" "mkdir shared" 3- Display directory permissions "/ls –l" You should see the result drwxr-xr-x root root drwx tork tork 4096 Jan 01:33 shared 4096 Jan 11:29 tork Any new created directory has the permission "755" by default , but the home directory of a user , has the permission 700 , why is that ? 4- Change your current work directory "cd /home/shared" 5- Create a new file "touch shared.txt" 6- Display the file permissions "ls –l shared.txt" You should see the result -rw-r r root root Jan 01:58 shared.txt Any new created file has the permission "644" by default , which means Read, write= Owner Read= Group Read= Others 7- Now add contents in the file by the command "seq" "seq 10 > shared.txt" 8- Display the file content "cat shared.txt" you should see the result [root@bird shared]# cat shared.txt 10 9- Switch to user "tork" using the command "su" "su tork" 10- Run the command "pwd" to check your current work directory You should see the result /home/shared 11- Run the command "whoami" to check which user logged in "whoami" you should see the result: tork 12- Display the "shared.txt" contents "cat shared.txt" you should see the result : 10 13- Now add contents in the file by the command "seq" "seq > shared.txt" You should see the result: [tork@bird shared]$ seq > shared.txt bash: shared.txt: Permission denied you can't edit or add contents to this file because you are logged in with the user tork , you only have the "read" permission 14- Create a new file "touch tork.txt" you should see the result: [tork@bird shared]$ touch tork.txt touch: cannot touch `tork.txt': Permission denied you can't create files or directories in the "shared" directory because you are logged in with the user tork , you only have the "execute" permission 15- Switch to user "root" "su –" Note that the system will ask you to enter the root's password 16- Run the command "pwd" You should see the result : /root 17- Change your working directory to "/home" "cd /home" 18- Change the "shared" directory permission to "757" "chmod 757 shared" 19- Change your working directory to the "shared" "cd shared" 20- Change the "shared.txt" permission to 666 "chmod 666 shared.txt" 21- Switch to user tork "su tork" 22- Display the content of the "shared.txt" "cat shared.txt" you should see the result: [tork@bird shared]$ cat shared.txt 10 23- Try now to add a contents to the "shared.txt" using the command "seq" "seq > shared.txt" Did you notice that you didn't get a permission error message? 24- Display the "shared.txt" contents "cat shared.txt" you should see the result: [tork@bird shared]$ cat shared.txt 25- Create a new file "tork.txt" "touch tork.txt" 26- Run the command "ls –l tork.txt" to check the files permission You should see the result: -rw-rw-r tork tork Jan 04:38 tork.txt This file has the read, write permissions to the file owner and the group 27- Change the "tork.txt" group to "it" "chmod –R :it tork.txt" you should see the result: [tork@bird shared]$ chown -R :it tork.txt chown: changing group of `tork.txt': Operation not permitted and that's because the user "tork" doesn't have the permission to change the group of a file 28- Switch to user "root" "su –" 29- Change the working directory "cd /home/shared" 30- Change the "tork.txt" group to "it" "chmod –R :it tork.txt" 31- Self assignment a- Add user "mostafa" to the group "it" b- Switch to user "mostafa" c- Add contents to file "tork.txt" using the "seq" command Linux Crash Course @ udemy.com Thank you Muhammed Tork ... working directory to the "shared" "cd shared" 20 - Change the "shared.txt" permission to 666 "chmod 666 shared.txt" 21 - Switch to user tork "su tork" 22 - Display the content of the "shared.txt" "cat... tork" 27 Run the "id" command to display user "tork" uid and groups "id tork" You should see uid=501(tork) gid=501(tork) groups=501(tork),503(sales) 28 Delete group "sales"" "groupdel sales" 29 Run... between password change now ? 20 Change the maximum number of days between password change & number of days of warning before password expire for user "tork" (self assignment) 21 Run the "chage –l tork"