Units 11-14 Assignments (RHEL9)

(4) Explain the four-layer TCP/IP model covered in Chapter 11.

Application - Each application has specifications for communication so that clients and servers may communicate across platforms.

Transport - Transport protocols are TCP and UDP.

Internet (or Network) - The Internet, or network layer, carries data from the source host to the destination host.

Link (or Network Interface) - The link, or media access, layer provides the connection to physical media.

(3) Explain the difference in an IPv4 host address and an IPv4 network address. How are the two addresses determined in a 32-bit number?

The address is divided into two parts: the network part and the host part.

All hosts on the same subnet, which can talk to each other directly without a router, have the same network part; the network part identifies the subnet.

No two hosts on the same subnet can have the same host part; the host part identifies a particular host on a subnet.

(1) What is a broadcast address?

The highest possible address on a subnet (host part is al lones in binary) is used for broadcast messages in IPv4, and is called the broadcast address.

(1) What is the purpose of the routing table on a Linux server?

To show routing information

(2) Explain the difference in automatic IP configuration of a Linux client (DHCP) as compared to static IP configuration.

Network addresses may be configured on interfaces manually by the administrator

Or dynamically from the network using DHCP

(1) What is the purpose of the gateway in IP configuration?

A network gateway connects different networks, and a network router commonly operates as the gateway for a subnet.

(2) Explain how Linux uses network interfaces as compared to network devices.

A device is a network interface.

A connection is a collection of settings that can be configured for a device.

(1) How are network interfaces defined in Linux?

Each network port on a system has a name, which you use to configure and identify it.

(1) What is the command to lookup the IP configuration on a RHEL server? (There are actually at least two ways to do this...do you know both commands?)

ip link show

(1) Assume that you are having trouble accessing the routes outside your LAN. What is the RHEL command to troubleshoot routes?

ip route

(1) When using the tracepath command, what do each of the lines in the output tell us? (BTW...try the traceroute command and see what happens.)

Identify whether an issue is with one of your routers or an intermediate one

(2) What does the Linux command ss do? How does ss compare to netstat?

The ss command is used to display socket statistics.

The ss command is meant to replace the older tool netstat, part of the net-tools package, which may be more familiar to some system administrators but which is not always installed.

(1) What is NetworkManager in RHEL8?

A daemon that monitors and manages network settings

(1) What does the Linux command nmcli do?

Create and edit connection files from the command line

(1) As demonstrated in Chapter 11, what is the RHEL9 command to change the IP address of eth0 to 192.168.0.190/24?

nmcli con mod eth0 ipv4.addresses 192.168.0.190/24

(1) What is the absolute reference to RHEL file that contains the configuration for eth1?

/etc/sysconfig/network-scripts/ifcfg-eth1

(3) What do these interface settings do: bootproto, onboot, and name?

bootproto specifies the method for assigning an IP address, such as static or DHCP.

onboot determines whether the network interface is activated when the system boots.

name defines the name of the network interface.

(5) Define the following RHEL9 commands or files?

a. hostname

b. hostnamectl

c. /etc/hosts

d. /etc/resolv.conf

e. /etc/hostname

a. Displays or temporarily modifies the system's fully qualified host name

b. Used to modify the /etc/hostname file and may be used to view the status of the system's fully qualified host name

c. Used to test host name resolution

d. Controls how testing host name resolution is performed

e. In Red Hat Enterprise Linux 7 and later, the static host name is stored in /etc/hostname.

(1) What is the Red Hat Subscription Management?

Red Hat Subscription Management provides tools that can be used to entitle machines to product subscriptions, allowing administrators to get updates to software packages and track information about support contracts and subscriptions used by the systems.

(4) Define these four tasks in the Red Hat Subscription Management system:

a. register

b. subscribe

c. enable repositories

d. review and track

a. Register a system to associate that system to a Red Hat account. This allows Subscription Manager to uniquely inventory the system. When no longer in use, a system may be unregistered.

b. Subscribe a system to entitle it to updates for selected Red Hat products. Subscriptions have specific levels of support, expiration dates, and default repositories. The tools can be used to either auto-attach or select a specific entitlement. As needs change, subscriptions may be removed.

c. Enable repositories to provide software packages. Multiple repositories are enabled by default with each subscription, but other repositories such as updates or source code can be enabled or disabled as needed.

d. Review and track entitlements that are available or consumed. Subscription information can be viewed locally on a specific system or, for an account, in either the Red Hat Customer Portal Subscriptions page or the Subscription Asset Manager (SAM).

(1) Write the command (CLI) to register a RHEL9 server with Red Hat Subscription Management.

subscription-manager register --username

(1) What is a Red Hat Subscription Management entitlement?

A subscription that has been attached to a system

(1) Define the naming convention syntax for an RPM file.

An RPM file naming convention follows the syntax name-version-release.architecture.rpm

(2) What is dnf? What is a dnf package?

Designed to be a better system for managing RPM-based software installation and updates

A software package in RPM format that can be installed, updated, or removed using the dnf tool

(1) What is a repository in dnf?

A storage location that holds RPM packages and metadata that dnf uses to find, install, and update software

(12) Define the following dnf commands:

a. dnf list

b. dnf search

c. dnf info

d. dnf provides

e. dnf update

f. dnf install

g. dnf remove

h. dnf grouplist

i. dnf group install

j. dnf history

k. dnf repolist all

l. dnf-config-manager

a. Lists all available, installed, or upgradable packages

b. Searches package names and summaries for a keyword

c. Displays detailed information about a specified package

d. Finds which package provides a specific file or capability

e. Updates all packages to the latest available versions

f. Installs a specified package and its dependencies

g. Removes a specified package from the system

h. Lists all available groups of packages

i. Installs all packages in a specified group

j. Shows a history of transactions made using dnf

k. Lists all enabled and disabled repositories

l. Used to enable, disable, or configure repositories

(7) Define the following rpm commands:

a. rpm -q

b. rpm -q -p

c. rpm -q -f

d. rpm -q -l

e. rpm -q -c

f. rpm -q -d

g. rpm -q --scripts

a. Queries the RPM database for a package installed on the system

b. Queries an RPM package file that is not installed

c. Finds out which installed package owns a specific file

d. Lists all files installed by a package

e. Lists configuration files installed by a package

f. Lists documentation files installed by a package

g. Displays the scripts (like pre-install or post-install) used by the package

(2) Define Linux file system. What is the advantage to the way Linux manages its file system(s)?

The Linux file-system hierarchy presents a collection of file systems on separate storage devices as if it were one set of files on one giant storage device that you can navigate.

Much of the time, you do not need to know which storage device a particular file is on, you just need to know the directory that file is in.

(1) What does the df -H Linux command do?

Provides an overview of the file-system mount points and the available free space in SI units

(1) What does the du -h /var/log Linux command do?

Displays the disk space usage of the /var/log directory and its contents in a human-readable format

(1) What is the /dev/sdb3 device on a Linux server?

The third partition on the second disk

(2) What is the UUID and why is it important when managing a RHEL file system?

A UUID is a unique ID assigned to a filesystem or partition when it's created.

It's important in RHEL because it provides a stable way to identify and mount filesystems, even if device names like /dev/sda change.

(1) What does the lsblk command do in RHEL?

Identify block devices in real time

(4) Explain the how the mount command works, including the two required arguments. Include at least one good example.

The mount command allows the root user to manually mount a file system.

The first argument of the mount command specifies the file system to mount.

The second argument specifies the directory to use as the mount point in the file-system hierarchy.

There are two common ways to specify the file system on a disk partition to the mount command.

(1) What is a mount point?

An empty directory

(1) Write the command to unmount the fourth partition on the third SATA drive on your Linux server.

umount /dev/sdc4

(1) What does the lsof Linux command do?

Shows a list of all open files on the system

(1) What is the default mount point for a USB flash drive on a RHEL server?

http://run/media/USERNAME/LABEL

(4) What is the difference between the locate command and the find command? Define and explain both.

The locate command finds files based on the name or path to the file. (a search string)

This database is NOT updated in real time, it static, and it must be frequently updated for results to be accurate.

The find command can search for files based on their ownership or permissions.

It is slower than locate, but more accurate.

(1) What does the updatedb command do in RHEL?

Updates the database used by the locate command

(1) What does the find /etc -name 'pass' command do in RHEL?

Searches the /etc directory for files with names matching pass

(1) What does the find /var/www/html -user student command do in RHEL?

Searches for files in /var/www/html that are owned by the user named student

(1) What does the find /home/joeblow -mmin +200 command do in RHEL?

Searches the /home/joeblow directory and its subdirectories for files whose content was modified more than 200 minutes ago

(1) Write a RHEL command to lookup all files matching *.conf on your server that are owned by the dnsmasq group starting in the /etc directory.

find /etc -name '*.conf' -group dnsmasq

(2) Describe the RHEL9 Web Console. Why is it important for Linux administrators?

Web Console is a web-based management interface for Red Hat Enterprise Linux 8 designed for managing and monitoring your servers.

You can use Web Console to monitor system logs and view graphs of system performance.

(2) What is the default TCP port used to access the Web Console? Write the firewall-cmd command used to open this port in firewalld.

9090

firewall-cmd --permanent --add-port=9090/tcp

(1) Why is the Web Console a good troubleshooting tool?

You can monitor basic system statistics in real time, inspect system logs, and quickly switch to a terminal session within Web Console to gather additional information from the command-line interface.

(1) Describe the Red Hat Customer Portal.

The Red Hat Customer Portal (https://access.redhat.com) provides customers access to documentation, downloads, tools, and technical expertise.

(1) What are the Customer Portal Labs?

The Customer Portal Labs section provides a collection of web-based applications and tools to help you improve performance, diagnose issues, identify security problems, and optimize your configurations.

(1) What is the Red Hat Product Security Center?

The Security section provides access to the Red Hat Product Security Center at https://access.redhat.com/security/.

(1) What is the redhat-support-tool?

The Red Hat Support Tool utility redhat-support-tool provides a text-based interface that allows you to search Knowledgebase articles and to file support cases on the Customer Portal from your system's command line.

(3) Before contacting Red Hat Support, what information should a Linux Administrator gather before submitting a bug report?

Define the problem

Gather background information

Determine the severity level

(4) Describe each of the following Severity Levels used by Red Hat Support:

a. Urgent (Severity 1)

b. High (Severity 2)

c. Medium (Severity 3)

d. Low (Severity 4)

An issue with a Red Hat Product or Service that is actively causing serious interruptions to your business critical operations. This is an issue requiring immediate attention as there is a significant risk to your business.

An issue with a Red Hat Product or Service that is partially functional (such as degradation of a service but the service is still available) and actively impacting your business operations. This is an issue on a business critical system requiring accelerated attention.

An issue with a Red Hat Product or Service that is currently functioning as expected but you either (1) recently experienced a degradation that you are monitoring or seeking a root cause for or (2) you are seeing indicators of a potential loss of functionality to a business critical system/

A non-urgent query regarding a Red Hat Product or Service. Typically, a query that does not involve any interruption to your business critical operations.

(1) What is a sosreport?

When support cases are in an opened or maintained status, users may attach files or documentation, such as diagnostic reports (sosreport). The tool uploads and attaches files to cases.

(1) Describe Red Hat Insights.

Red Hat Insights is a predictive analytics tool to help you identify and remediate threats to security, performance, availability, and stability to systems running Red Hat products in your infrastructure.

(2) What are the benefits of using Red Hat Insights?

Red Hat Insights is delivered as a Software-as-a-Service (SaaS) product, so you can deploy and scale it quickly with no additional infrastructure requirements.

For each issue that is detected, Red Hat Insights provides estimates of the risk presented and recommendations on how to mitigate or remediate the problem.