Linux RHCSA Preparation

RHCSA

1. Start classroom-rh124; 

2. Set environment: tar xvf rhcsaexam.tar -C /

3. Start server-rh124

4. Set lab environment: lab examrhcsa setup

5. Check result: lab examrhcsa grade

Questions

1. Reset root password

A. Restrat the system;

B. In the login page, choose the first line and input "e"

C. Go to line start with "Linux16";

D. Add "rd.break" at the end of the line

E. If there is no "console=tty0" in the line, need to add it before "rd.break"

F. Press "Ctrl+x"

G. If screen shows "switch_root:/#", please do following steps

H. re mount the file system: mount -o remount,rw /sysroot

I. Go to /sysroot: chroot /sysroot

J. Change password: echo 'ooxx9527' | passwd --stdin root

K. Create file: touch /.autorelabel

L. Input "exit" twice to restart the system

2. Change hostname, network config

A. Change hostname: hostnamectl set-hostname server0.example.com

B. Check hostname: hostnamectl

C. Use graphic to change network config: nm-connection-editor

D. Use command to restart the network: nmcli connection down eth0 / nmcli connection up eth0

E. Check network config: nmcli connection show eth0

3. Set selinux

A. Check selinux: getenforce

B. Change selinux config file: vim /etc/sysconfig/selinux

From "SELINUX=permissive" to "SELINUX=enforcing"

C. After restart the system will using enforcing

D. Temporary change to enforcing: set enforce 1

4. Set Yum source

A. Verify the link 

B. Add yum source: yum-config-manager --add-repo="<url>"

C. Verify the repo: yum repolist

5. Change LV size

Check device: lsblk

A. Check the lv information: lvs

B. Check the vg information: vgs

C. Check the pv information: pvs

D. Check the mount point: df -h

E.  Create new PV: 

i. Create new partition: fdisk /dev/sdb --> p --> n --> p --> enter --> enter --> +500M --> P --> t --> 2 --> 8e --> w

ii. Check new partition: ll /dev/sdb2

iii. If not available, input command: partx -a /dev/sdb

iv. Create PV: pvcreate /dev/sdb2

F.  Add PV to VG: vgextend vg1 /dev/sdb2

G. Extend lv: lvextend -L 770M /dev/vg1/lvm1

H. Extend filesystem: 

i. Check the type of lv: blkid

ii. If the type is xfs, use command to extend filesystem: xfs_growfs /vg1/lvm1

iii. If the type is ext4, use command to extend filesystem: resize2fs /dev/vg1/lvm1

I. Check the filesystem ls /vg1/lvm1

6. Create user and usergroup

A. Create group: groupadd -g 40000 adminuser

B. Create user: useradd -G adminuser natasha

C. Create user: useradd -G adminuser harry

D. Create user: useradd -s /sbin/nologin sarah

E. Change password: echo 'glegunge' | passwd --stdin natasha

F. Change password: echo 'glegunge' | passwd --stdin harry

G. Change password: echo 'glegunge' | passwd --stdin sarah

7. File Privilege

A. Copy file: cp /etc/fstab /var/tmp

B. Check file: ll /var/tmp/fstab

C. Change owner: chown root:root /var/tmp/fstab

D. Remove execute: chmod u-x,g-x,o-x /var/tmp/fstab

E. Give natasha read and write: setfacl -m user:natasha:rw-,user:harry:---,other::r-- /var/tmp/fstab

F. Check facl: getfacl /var/tmp/fstab

8. Create task

A. Set crond automatic start: systemctl enable crond

B. Create task based on natasha: crontab -u natasha -e

23 14 * * * /bin/echo "rhcsa"

C. Check: crontab -u natasha -l

9. Speical File Privilege

A. Create folder: mkdir /home/admins

B. Change owner: chgrp adminuser /home/admins

C. Check the result: ll -d !$

D. Change privilege: chmod g=rwx,o=--- /home/admins

E. Change privilege: chmod g+s /home/admins

F. Check

i. touch /home/admins/1.txt 

ii. ll /home/admins/1.txt

10. Upgrade Kernel

A. Check the version before upgrade: uname -r

B. Install package: rpm -ivh <path in introduction>

C. Check the version after upgrade: uname -r

D. Restart the system: init 6

11. LDAP Client Config

A. edit the yum config file: vim /etc/yum.repos.d/classroom.example.com_content_rhel7.0_x86_64_dvd.repo

Add: gpgcheck=0

B. Install package: yum install sssd authconfig-gtk krb5-workstation -y

C. Config: authconfig-gtk

D. Follow the question to config the LDAP

E. Use username to verify: getent pwd ldapuser0

F. Use ssh to verify with password "kerberos": ssh ldapuser0@localhost 

G. Use command to exit: logout

12. Config LDAP auto mount

A. Install package: yum install autofs -y

B. Enable autofs service: systemctl enable autofs

C. Start autofs service: systemctl start autofs

D. Check the NFS folder: showmount -e classroom.example.com

E. Set the auto mount: 

i. Change file: vim /etc/auto.master

Add: /home/guests /etc/auto.master.d/ldapusers.autofs

ii. Create file: vim /etc/auto.master.d/ldapusers.autofs

Add: * -rw    classroom.example.com:/home/guests/&

F. Create local folder: mkdir /home/guests

G. Change privilege: chmod 777 /home/guests

H. Restart the service: systmctl restart autofs

I. Verify the setting with password "kerberos": ssh ldapuser0@localhost

Show [ldapuser0@server0 ~]$

J. Verify the setting with: mount

K. Use command to exit: exit

13. Time Sync

A. Install package: yum install chrony -y

B. Check time setting: timedatectl

C. Enable the service: systemctl enable chronyd

D. Start the service: systemctl start chronyd

E. Enable the ntp: timedatectl set-ntp true

F. Modify the time server: vim /etc/chrony.conf

i. Add: server classroom.example.com iburst

ii. Add # before all other time server

G. Restart the time: systemctl restart chronyd

H. Manually sync: chronyc --> waitsync

I. Verify the setting: timedatectl

14. Tar files

A. tar file: tar cvf /root/sysconfig.tar.bz2 /etc/sysconfig

B. Check file: ll /root/sysconfig.tar.bz2

C. Check file: tar tf /root/sysconfig.tar.bz2

15. Add user

A. Create user: useradd -u 3456 alex

B. Set password: echo "glegunge" | passwd --stdin alex

16. Create SWAP 

A. Check partition: lsblk

B. Create partition: fdisk /dev/sdb --> p --> n --> p --> enter --> enter --> +512M --> p --> t --> L --> 82 --> w

C. Check partitino: ll /dev/sdb3

D. If not exist, input command: partx -a /dev/sdb

E. Make swap partition: mkswap /dev/sdb3

F. Set auto mount: 

i. copy the <UUID>

ii. vim /etc/fstab

Add: <UUID> swap swap defaults 0 0

G. Manually start swap:  swapon -a

H. Check swap: free -m

I. Restart the system to verify the swap

17. Find files

A. Create destination folder: mkdir /root/findfiles

B. Find files: find / -user ira -exec cp -a {} /root/findfiles/ \;

C. Check result: ll /root/findfiles

18. Filter files

A. Find keywords and input into file: grep "seismic" /usr/share/dict/words > /root/wordlist

B. Check file: cat /root/wordlist

19. Create Logical Volumn

A. Check partition: lsblk

B. Create partition: fdisk /dev/sdb --> p --> n --> p --> enter --> enter --> enter --> p --> t --> 8e -> w

C. Check partitino: ll /dev/sdb4

D. If not exist, input command: partx -a /dev/sdb

E. Create PV: pvcreate /dev/sdb4

F. Create VG: vgcreate -s 16M exam /dev/sdb4

G. Check VG: vgdisplay exam

H. Create LV: lvcreate -l 8 -n lvm2 exam

I. Check LV: lvs / lvdisplay /dev/exam/lvm2

J. Format LV: mkfs.xfs /dev/exam/lvm2

K. Auto Mount: 

i. Create folder:  mkdir -p /exam/lvm2

ii. find UUID for lv: blkid

iii. vim /etc/fstab

Add: <UUID>  /exam/lvm2 xfs defaults 0 0 

L. Check fs: mount /exam/lvm2