In this tutorial, How to Install Chrony and Configure NTP server in Linux. Chrony is used to sync the system clock from different NTP servers.

Chrony with two programs: chronyc is the command-line interface for chrony and chronyd is the daemon that can be started at boot time.

Install chrony

# yum -y install chrony    # CentOS/RHEL
# apt install chrony       # Debian/Ubuntu
# dnf -y install chrony    # Fedora 22+

Configure chrony

[vagrant@DevopsRoles ~]$ sudo vi /etc/chrony.conf

Example add lines as below

# change servers for synchronization
#server 0.centos.pool.ntp.org iburst
#server 1.centos.pool.ntp.org iburst
#server 2.centos.pool.ntp.org iburst
#server 3.centos.pool.ntp.org iburst
server 0.asia.pool.ntp.org
server 1.asia.pool.ntp.org
server 2.asia.pool.ntp.org
server 3.asia.pool.ntp.org
# Allow NTP client access from local network.
allow 10.0.2.0/24

Start and enable daemon upon boot

[vagrant@DevopsRoles ~]$ sudo systemctl start chronyd 
[vagrant@DevopsRoles ~]$ sudo systemctl enable chronyd

If Firewalld is running, allow port 123/UDP.

[vagrant@DevopsRoles ~]$ sudo firewall-cmd --add-service=ntp --permanent 
[vagrant@DevopsRoles ~]$ sudo firewall-cmd --reload

Check Chrony Synchronization

[vagrant@DevopsRoles ~]$ chronyc sources
[vagrant@DevopsRoles ~]$ chronyc tracking

Conclusion

You have installed Chrony and Configured the NTP server. I hope will this your helpful. Thank you for reading the DevopsRoles page!

Use the MTR command in Linux to view the traceroute report for a remote machine. As a network administrator, you need to learn the usage of mtr command to Diagnosing Network issues.

MTR command is a powerful tool to diagnose and isolate networking errors and provide reports of the network.

Install MTR command in Linux

Ubuntu/Debian

sudo apt update && apt upgrade
sudo apt install mtr-tiny

CentOS/RHEL/Fedora

sudo yum update
sudo yum install mtr

macOS

brew install mtr

The Syntax mtr command

$ mtr [domainName/IP]

Example

[vagrant@DevopsRoles ~]$ mtr devopsroles.com

The output as below

How to view hostnames and numeric IP addresses

[vagrant@DevopsRoles ~]$ mtr -b google.com

The output as picture below

Enable Report Mode

[vagrant@DevopsRoles ~]$ mtr -r -c 10 google.com >mtr-report-google

The output report as below

Conclusion

MTR commands a network diagnostic tool. More information “$ man mtr” command in Linux. Thank you for reading the DevopsRoles page!

Introduction

In this tutorial, How to install an RPM package into a different directory on Centos. Installing RPM packages is a common task for Linux users, especially those working with Red Hat-based distributions like Fedora, CentOS, or RHEL. Sometimes, you may need to install an RPM package into a different directory than the default.

What is an RPM Package?

RPM stands for Red Hat Package Manager. It is a package management system used by Red Hat-based distributions to manage software installation, updates, and removals. RPM packages are precompiled binaries that simplify software distribution and installation.

Why Install RPM Packages into a Different Directory?

There are several reasons why you might want to install an RPM package into a different directory:

1. Space Constraints: Your default installation directory might be running out of space.
2. Testing: You may want to test a package in a separate environment before moving it to production.
3. Custom Configurations: Some applications may require custom directory structures.

For example, Install package bind install into another directory /opt/bind.

Use rpm -qi command to check the package has been installed but not yet

$ sudo rpm -qi [name-package]

Not all RPM packages can be installed into another directory.

For example, the bind RPM package is not relocatable. You install it then the error: package bind is not relocatable

[vagrant@DevopsRoles ~]$ rpm -qpi bind-9.8.2-0.68.rc1.el6_10.1.x86_64.rpm | head -1
Name        : bind                         Relocations: (not relocatable)

Install an RPM package into a different directory.

For example, wkhtmltox RPM package as below

[vagrant@DevopsRoles ~]$ wget https://downloads.wkhtmltopdf.org/0.12/0.12.5/wkhtmltox-0.12.5-1.centos6.x86_64.rpm

[vagrant@DevopsRoles ~]$ rpm -qpi wkhtmltox-0.12.5-1.centos6.x86_64.rpm | head -1
Name        : wkhtmltox                    Relocations: /usr/local

[vagrant@DevopsRoles ~]$ sudo rpm -ivh --prefix=/opt/wkhtmltox wkhtmltox-0.12.5-1.centos6.x86_64.rpm

Check the result installed wkhtmltox on your system.

[vagrant@DevopsRoles ~]$ tree /opt/wkhtmltox
/opt/wkhtmltox
├── bin
│   ├── wkhtmltoimage
│   └── wkhtmltopdf
├── include
│   └── wkhtmltox
│       ├── dllbegin.inc
│       ├── dllend.inc
│       ├── image.h
│       └── pdf.h
├── lib
│   ├── libwkhtmltox.so -> libwkhtmltox.so.0.12.5
│   ├── libwkhtmltox.so.0 -> libwkhtmltox.so.0.12.5
│   ├── libwkhtmltox.so.0.12 -> libwkhtmltox.so.0.12.5
│   └── libwkhtmltox.so.0.12.5
└── share
    └── man
        └── man1
            ├── wkhtmltoimage.1.gz
            └── wkhtmltopdf.1.gz

7 directories, 12 files

FAQs

Can all RPM packages be relocated?

No, not all RPM packages support relocation. You need to check the package metadata using the rpm -qpi command to see if it supports relocation.

What if the RPM package does not support relocation?

If the RPM package does not support relocation, you can use the rpm2cpio and cpio method to manually extract and place the files in your desired directory.

How do I handle dependencies when relocating RPM packages?

Handling dependencies can be tricky when relocating RPM packages. You may need to manually resolve and relocate dependencies as well. Adjusting environment variables and creating symbolic links can help in managing dependencies.

Is it safe to relocate RPM packages?

Relocating RPM packages can be safe if done correctly. However, it can lead to unexpected behavior if not handled properly, especially with packages that have strict directory dependencies.

Can I use package managers like Yum or DNF to relocate packages?

Yum and DNF do not support package relocation directly. You need to use the RPM command with the --relocate option or manually extract the package using rpm2cpio and cpio.

Conclusion

Installing an RPM package into a different directory can be useful for various reasons, including space management, testing, and custom configurations. While not all RPM packages support relocation, the methods outlined in this guide provide a comprehensive approach to handling different scenarios. Whether using the RPM command with relocation options or extracting packages manually with rpm2cpio and cpio, these techniques will help you manage your RPM packages effectively. I hope will this your helpful. Thank you for reading the DevopsRoles page!

Introduction

In this tutorial, How to generate a random password using the OpenSSL command in Linux. It generates a number of random bytes, which the output HEX or Base64.

In today’s digital landscape, securing sensitive information is more important than ever. Passwords play a critical role in maintaining data privacy, and generating strong, random passwords is a cornerstone of cybersecurity. OpenSSL, a powerful cryptographic toolkit, offers a reliable way to generate random passwords.

This guide delves into how to use the OpenSSL command line tool to generate secure passwords, along with practical examples and tips to enhance your security strategy.

What Is OpenSSL?

OpenSSL is an open-source implementation of the SSL and TLS protocols. It’s widely used for tasks such as encrypting data, generating certificates, and managing cryptographic keys. One lesser-known but highly valuable feature of OpenSSL is its ability to generate random passwords. By leveraging its robust pseudo-random number generator, OpenSSL creates secure passwords that are nearly impossible to predict.

Why Use OpenSSL to Generate Random Passwords?

• Enhanced Security: OpenSSL’s random number generation ensures high entropy, reducing the risk of brute-force attacks.
• Customizability: You can tailor the password length and character set to meet specific security requirements.
• Convenience: With a single command, you can generate passwords for a variety of applications, from securing databases to encrypting files.
• Cross-Platform Compatibility: OpenSSL works on Linux, macOS, and Windows, making it a versatile tool.

How to Use OpenSSL to Generate Random Passwords

Generating a Basic Password

The simplest way to generate a random password with OpenSSL is by using the rand command. Here’s an example:

openssl rand -base64 12

• rand: Invokes the random number generator.
• -base64: Specifies the encoding format.
• 12: Defines the number of bytes to generate.

Output Example:

3kHnP1T+/rJcWg==

This command generates a 12-byte random password encoded in Base64. Base64 encoding is ideal for generating passwords because it includes a mix of alphanumeric characters and special symbols.

The Base64 the output is a good password.

The syntax OpenSSL generate random password

# For Base64
openssl rand -base64 NUMBER
# For HEX
openssl rand -hex NUMBER

For example

[vagrant@DevopsRoles ~]$ openssl rand -base64 10
QwPFPP2qZIVasw==
[vagrant@DevopsRoles ~]$ openssl rand -hex 8
6a3853934292970b

Generating Hexadecimal Passwords

For situations where you need passwords in hexadecimal format, use:

openssl rand -hex 16

• -hex: Specifies the hexadecimal output format.
• 16: Generates a 16-byte random password.

Output Example:

1f3b8d4e92a7c4d5a6b7c8f9e0d2a1b3

Generating Custom-Length Passwords

If you need a password of a specific length, adjust the byte size accordingly. For instance, to generate a 32-character password:

openssl rand -base64 24

Why 24 bytes? Each Base64-encoded character represents 6 bits, so 24 bytes (192 bits) yield a 32-character string.

Adding Special Characters

To include special characters, pipe the output through tr or a similar tool. Here’s an example:

openssl rand -base64 16 | tr -dc 'A-Za-z0-9!@#$%^&*()'

• tr -dc: Filters the output to include only the specified characters.

Output Example:

aB2!C3d@E4f^G5

Automating Password Generation with Scripts

For repetitive tasks, automate password generation using shell scripts. Here’s an example:

#!/bin/bash
for i in {1..5}
do
  openssl rand -base64 16
done

This script generates five random passwords in one execution.

Use Cases for OpenSSL Passwords

• Database Credentials: Secure sensitive databases with strong passwords.
• Encryption Keys: Generate passwords for encrypting files or storage devices.
• Web Applications: Strengthen authentication by using unique passwords for user accounts.
• System Administration: Secure servers and applications with randomly generated credentials.

Frequently Asked Questions

1. Is OpenSSL a reliable tool for generating passwords?

Yes, OpenSSL is widely regarded as a reliable tool for generating secure passwords due to its robust random number generator.

2. Can I control the character set in OpenSSL passwords?

Yes, you can filter the output using tools like tr to include or exclude specific characters.

3. Are Base64-encoded passwords secure?

Base64 passwords are secure but may need additional complexity for applications requiring special characters.

4. What is the difference between -base64 and -hex?

• -base64 produces a mix of alphanumeric characters and symbols.
• -hex generates passwords in hexadecimal format.

5. How do I ensure my password is sufficiently random?

Use a higher byte size for increased randomness and avoid reusing passwords.

Additional Resources

• OpenSSL Official Documentation
• Cybersecurity Best Practices
• Linux Man Pages for OpenSSL

Conclusion

Using OpenSSL to generate random passwords is a quick and effective way to bolster your security measures. Whether you need simple Base64-encoded passwords or complex strings with special characters, OpenSSL provides the flexibility to meet your requirements. By mastering these commands and integrating them into your workflow, you can protect sensitive data and ensure a robust security posture. Start experimenting with OpenSSL today and take the first step toward enhanced password security.

Thought the article, How to use “OpenSSL generate random password” as above. I hope will this your helpful. Thank you for reading the DevopsRoles page!

Introduction

In this tutorial, How to monitor your system using Grafana InfluxDB and Telegraf. This article will guide you through the process of setting up and using these tools, from basic configurations to advanced monitoring techniques.

What is Monitoring with Grafana InfluxDB and Telegraf?

Monitoring with Grafana, InfluxDB, and Telegraf involves collecting, storing, and visualizing time-series data. Telegraf is responsible for gathering data from various sources, InfluxDB stores this data, and Grafana visualizes it through customizable dashboards.

Benefits of Using Grafana, InfluxDB, and Telegraf

1. Real-time Monitoring: Visualize data in real-time to quickly identify and address issues.
2. Scalability: Easily scale your monitoring setup to handle increased data volumes.
3. Customization: Create personalized dashboards to suit your specific monitoring needs.

My example is Grafana InfluxDB, Telegraf as in the picture below:

• Server01 -> 192.168.3.5
• Server02 -> 192.168.3.6
• InfluxDB and Grafana -> 192.168.3.4

Install Grafana Influxdb and Telegraf on Linux

• InfluxDB
• Grafana
• Telegraf

Configure Grafana InfluxDB and Telegraf

InfluxDB configure

For my example, create 2 Databases with a 14-day retention policy.

[root@DevopsRoles ~]# influx
Connected to http://localhost:8086 version 1.7.6
InfluxDB shell version: 1.7.6
Enter an InfluxQL query
> show databases
name: databases
name
----
telegraf
mydb
_internal
> CREATE DATABASE mydb WITH DURATION 14d
> CREATE DATABASE telegraf WITH DURATION 14d

Open and edit the file /etc/influxdb/influxdb.conf as below

[[opentsdb]]		
   enabled = true		
   bind-address = ":4243"		
   database = "mydb"		
[[opentsdb]]		
   enabled = true		
   bind-address = ":4242"		
   database = "telegraf"

Telegraf Configure

For example, create file configuration as below

$ telegraf -sample-config -input-filter cpu:mem:swap:net -output-filter influxdb > telegraf.conf

Edit and modify the file /etc/telegraf/telegraf.conf for server01

[[outputs.influxdb]]		
  urls = ["http://192.168.3.4:8086"]		
  database = "telegraf"	

Grafana Configure

Add Data Sources for InfluxDB of Server01 as in the picture below

Import the Telegraf JSON template as the picture below

The result of Monitoring with Grafana InfluxDB Telegraf

Frequently Asked Questions (FAQs)

What is the role of Telegraf in the monitoring stack?

Telegraf collects and sends data from various sources to InfluxDB for storage.

How do I create custom dashboards in Grafana?

You can create custom dashboards by adding and configuring panels within Grafana.

Can I set up alerts in Grafana?

Yes, Grafana supports alerting, which can notify you about critical events.

How do I scale my monitoring setup?

You can scale by adding more Telegraf agents, increasing InfluxDB storage, and optimizing Grafana dashboards.

Conclusion

You have Monitored with Grafana InfluxDB and Telegraf. I hope will this your helpful. Thank you for reading the DevopsRoles page!