rhcsa

Source Link Study 

# https://www.youtube.com/watch?v=D2H2_ZCFShY

# https://meetdarji28.blogspot.com/2020/05/red-hat-certified-systems-administrator.html

RHCSA E@AM Questions & Answers

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RHCSA-VM configuration:


*you have been provided a virtual box named as serverX.example.com (hint:where X is your domain number)
* password for both virtual machines should be “Postroll”
*serverX.example.com provided with ip=172.25.X.11/255.255.255.0
*serverX.example.com are provided with gateway 172.25.254.254 & example.com dns domain with the IP: 172.25.254.254


*NOTE: I have Foundation Machine# 9, so I am using 172.25.9.11


#nmcli connection add con-name eth0 ifname eth0 type ethernet ip4 172.25.9.11/24 gw4 172.25.254.254
#nmcli connection modify eth0 ipv4.dns 172.25.254.254
#nmcli connection modify eth0 ipv4.method manual
nmcli connection modify eth0 connection.autoconnect true
#nmcli connection down eth0
#nmcli connection up eth0

—————————-
* Set the Hostname


hostnamectl set-hostname server9.example.com
Before starting exam.
–> ping server-vm ip , desktop-vm ip and classroom.example.com
–> from server-vm ping base machine and server.
–> check hostname and IP address of server-vm and desktop-vm

ping 172.25.9.11
ping 172.25.9.10
ping 172.25.254.254
ping 172.25.254.9 ----> Your base Machine
ping example.com

* if the vm has set with multi-user.target then set it to graphical.target, but don’t forget to revert back to multi-user.target

systemctl get-default --> to check the running target

systemctl set-default graphical.target

—> mask the iptable servervice before starting exam.

systemctl mask iptables.service
systemctl mask ip6tables.service

1) configure Selinux



The machine should be running enforcing mode

vim /etc/selinux/config

Change this
SELINUX=enforcing

Don’t forget to Reboot it, so that I’ll take affect

2) create a new 100MB Physical partition mounted under /gluster


(Note because partition sizes are seldom exactly what is specified when they are created, any thing within the range of 70MB to 120MB is acceptable)

fdisk /dev/vdb ----- > Create the Partition of 100M
partx /dev/vdb
mkfs.ext4 /dev/vdb2 ------> Make a filesystem on it
mkdir -p /gluster -----> Create Directory to mount on it
blkid ------> Get the UUID of it
vim /etc/fstab --------> Create the mount point inside the fstab

UUID=c3ac5a96-80a9-44c3-b51e-9531e9ed9f08 /gluster ext4 defaults 0 0

mount -a ------> Mount it
df -hT ----> verify it is mounted 

3) create a new 150MB swap partition f/s.


(Note because partition sizes are seldom exactly what is specified when they are created, any thing within the range of 130MB to 170MB is acceptable)

fdisk /dev/vdb ----- > Create the Partition of 150M and set it's type 82 (which set its the swap type partition)
partx /dev/vdb --- If you didn't get the partition, just reboot the system, don't get panic
mkswap /dev/vdb3 ---> Make the swap on newly created Partition
swapon /dev/vdb3
swapon -a

vim /etc/fstab --------> Create the mount point inside the fstab

UUID=4f3e868d-c885-4e1f-b069-d56ba443a9b6 swap swap defaults 0 0

Verify:

free -m
swapon -s

4) create a repositary for http://content.example.com/rhel7.0/x86_64/dvd


vim /etc/yum.repos.d/rhcsa.repo

[localrepo]
name = Local Repo for RHCSA exam
baseurl = [url="http://content.example.com/rhel7.0/x86_64/dvd"]http://content.example.com/rhel7.0/x86_64/dvd[/url]
gpgcheck = 0
enabled = 1

Test:
yum clean all
yum list all
yum repolist

5) create the following user, groups, and group memberships:



–> A group named sysgrp
–> A user andrew who belongs to sysgrp as a secondary group
–> A user susan also belongs to sysgrp as a secondary group
–> A user sarah who does not have access to an interactive shell on system and who not a member of sysgrp
–> susan,sarah, andrew password = “Postroll”

groupadd sysgrp
useradd andrew
useradd susan
useradd -s /sbin/nologin sarah

usermod -aG sysgrp andrew
usermod -aG sysgrp susan

Verification:

# id andrew
uid=1002(andrew) gid=1003(andrew) groups=1003(andrew),1002(sysgrp)

# id susan
uid=1003(susan) gid=1004(susan) groups=1004(susan),1002(sysgrp)

# su - sarah

This account is currently not available.

6) create a collaborative directory /redhat/sysgrp with the following characteristics:


–> Group owneship of /redhat/sysgrpis sysgrp
–> The directory should be readbale,writable, and accessable to members of sysgrp, but not to any other user.

(It is understood that root has access to all files and directories on the system.

–> Files created in /redhat/sysgrp automatically have group ownership set to the sysgrp group

mkdir -p /redhat/sysgrp
chgrp sysgrp /redhat/sysgrp
chmod 2770 /redhat/sysgrp

Verification:

# ls -ld /redhat/sysgrp
drwxrws---. 2 root sysgrp 6 Jun 15 23:21 /redhat/sysgrp

7) Install the appropriate kernel update from http://content.example.com/rhel7.0/x86_64/errata


The following criteria must also be met:
–>The updated kernel is the default kerneal when the system rebooted.
–>The original kernel remains available and bootable on the system

vim /etc/yum.repos.d/rhcsa.repo

[kernelrepo]
name = Local Repo for Kernel
baseurl = [url="http://content.example.com/rhel7.0/x86_64/errata"]http://content.example.com/rhel7.0/x86_64/errata[/url]
gpgcheck = 0
enabled = 1
 
yum repolist
Run this command before installing the kernel
uname -rms
Linux 3.10.0-123.el7.x86_64 x86_64

Install the kernel
yum install kernel

After Kernel installation, reboot the system and run this command again

# uname -rms
Linux 3.10.0-123.1.2.el7.x86_64 x86_64

8) Enable IP forwarding on your machine


vim /etc/sysctl.conf

net.ipv4.ip_forward = 1
Enable it using:
sysctl -p

9) The user andrew must configure a cron job that runs daily at 14:23 local time and executes – /bin/echo hiya



yum install cronie

systemctl enable crond
systemctl start crond
crontab -eu andrew

23 14 * * * /bin/echo hiya

Verification:
crontab -el andrew




10) Bind with LDAP used provided by classroom.example.com for userr authentication.


Note the following:-
–> The LDAP search base DN is dc=example,dc=com
–> The LDAP certificate file is
http://classroom.example.com/pub/EXAMPLE-CA-CERT
–>ldapuserX should be able to log into your system, whereX is your ServerX ((hint:where X is your domain number), but will not have a home directory, until you have completed the autofs requirement,below all LDAP users have password of “password”

yum install authconfig-gtk sssd krb5-workstation

#autoconfig-gtk ---------------------------> Fill the information

systemctl start sssd
systemctl enable sssd

Verification:

# getent passwd ldapuser9
ldapuser9:*:1709:1709:LDAP Test User 9:/home/guests/ldapuser9:/bin/bash

#ssh ldapuser9@localhost

11) configure autofs to automount the home directories of LDAP users,


Note the following:
–>classroom.example.com (172.25.254.254), NFS-exports /home/guests to your system, whereX is your server Number.
–>LDAP userX’s home directory is classroom.example.com:/home/guests/ldapuserX
–>LdapuserX’s home directory should be automounted locally beneath /home as /home/guests/ldapuserX
–>home directories must be writable by their users
–>while you are able to login as any of the users ldapuser1 through ldapuser20 the only home directory that is accessible from
your system is ldapuserX.
Example:- classroom.example.com would configure the automaster such that ldapuser100’s home directory /home/guests/ldapuserX gets mounted automatically upon login. The NFS share would be classroom.example.com:/home/guests/ldapuser100

yum install autofs

vim /etc/auto.master.d/home.autofs

/home/guests /etc/auto.home

vim /etc/auto.home

ldapuser9 -rw,sync classroom.example.com:/home/guests/&

systemctl enable autofs
systemctl start autofs

Verification:
#ssh ldapuser9@localhost

[ldapuser9@server9 ~]$ df -h
Filesystem                                                                      Size Used Avail Use% Mounted on
/dev/vda1                                                                        10G 3.4G 6.7G 34% /
devtmpfs                                                                         901M    0 901M 0% /dev
tmpfs                                                                            921M    0 921M 0% /dev/shm
tmpfs                                                                            921M 17M 904M 2% /run
tmpfs                                                                            921M    0 921M 0% /sys/fs/cgroup
/dev/vdb2                                                                        93M 1.6M 85M 2% /gluster
classroom.example.com:/home/guests/ldapuser9 10G 3.4G 6.7G 34% /home/guests/ldapuser9 --------> This line should be present

12) Configure your system so that it is an NTP client of classroom.example.com


yum install chrony

vim /etc/chrony.conf

server classroom.example.com iburst

systemctl restart chronyd
systemctl enable chronyd

Verification:
chronyc sources -V --> to check the reach level

13) copy the file /etc/fstab to /var/tmp

configure the permission of /var/tmp/fstab so that
the file /var/tmp/fstab is owned by the root user, belongs to the group root
should not be executable by anyone.
The user andrew is able to read & write /var/tmp/fstab
The user susan can neighter write nor read /var/tmp/fstab
All other users (current or future) have the ability to read /var/tmp/fstab.

cp /etc/fstab /var/tmp/

chown root:root /var/tmp/fstab

setfacl -m u:andrew:rw- /var/tmp/fstab
setfacl -m u:susan:--- /var/tmp/fstab

Verification:

getfacl /var/tmp/fstab
# su - andrew

[andrew@server9 ~]$ vim /var/tmp/fstab ----> Try to write anything to the file and it should be successful
[andrew@server9 ~]$ exit
logout

# su - susan
[susan@server9 ~]$ cat /var/tmp/fstab
cat: /var/tmp/fstab: Permission denied -----> It should show this error
[susan@server9 ~]$ exit
logout

14) Resize the logical volume, logical-data and it filesystem to 400MB.


Make sure that the filesystem contents remain intact.
(Note: partitions are seldom exactly  the size requested,so any thing within the range of 370MB to 430MB is acceptable)
df -Th -------> get the mount point of it
 
umount /datasource
e2fsck f /dev/datacontainer/datacopy
resize2fs /dev/datacontainer/datacopy 400M
lvreduce L 400M /dev/datacontainer/datacopy
mount -a

15) Add the user talusan with userid 2985


useradd -u 2985 talusan

Verification:

# id talusan
uid=2985(talusan) gid=2985(talusan) groups=2985(talusan)

find the file which owned by user julice and copy the file into /root/findresults directory.
mkdir -p /root/findresults

find / -user julice -exec cp -rfp {} /root/findresults/ \;

16) create a new physical volume, create a new volume group in the name of datacontainer, vg extent is 16.00MB



create a new logical volume in the name of datacopy with the size of 50 extents and file system must vfat then
mount it under /datasource

fdisk /dev/vdb ----- > Create the Partition of 802M[ (16*50) + 2 ] and set it's type 8e (which is LVM type)

partx /dev/vdb --- If you didn't get the partition, just reboot the system, don't get panic

pvcreate /dev/vdb5

vgcreate -s 16M datacontainer /dev/vdb5

vgdisplay -----> Check the vg extent size, its should be this (PE Size 16.00 MiB)

lvcreate -l 50 -n datacopy datacontainer

lvdisplay ------------> Check the size of extents and it should be(Current LE 50)

mkfs.vfat /dev/datacontainer/datacopy ------> Make a filesystem on it

mkdir -p /gluster -----> Create Directory to mount on it

blkid /dev/datacontainer/datacopy -----> get the UUID of /dev/datacontainer/datacopy

vim /etc/fstab --------> Create the mount point inside the fstab

UUID=C553-2BF5 /datasource vfat defaults 0 0

mount -a

Verification:
df -hT ----> verify it is mounted

17) create an archive file /root/local.tgz for /usr/local. it should be compressed by gzip.


tar -cvzf /root/local.tgz /usr/local

18) search the string sarah in the /etc/passwd file and save the output in /root/lines



grep sarah /etc/passwd > /root/lines

# cat lines
sarah:x:1004:1005::/home/sarah:/sbin/nologin