Category Archives: Linux

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Linux

Mastering the Netstat Command in Linux: A Comprehensive Guide with Examples

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Introduction

Welcome to this tutorial where I’ll guide you through the basics to advanced uses of the netstat command in Linux, with practical examples to help you master this tool.

What is Netstat?

Netstat is a command-line utility used to display all active network connections, both incoming and outgoing, on Unix, Linux, and Windows NT-based systems. It’s invaluable for network administration and monitoring.

Details can be found on the netstat command manual page:

[root@DevopsRoles ~]# man netstat | more

Detailed Usage of the Netstat Command in Linux

Here’s how you can use the netstat command in Linux to explore various network statistics:

1. List all LISTENING Ports of TCP and UDP connections using netstat -a option

2. Viewing Open TCP Socket Connections

This displays all active TCP connections. Execute this command to see detailed socket information.

[root@DevopsRoles ~]# netstat -nplt
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name
tcp        0      0 127.0.0.1:8088          0.0.0.0:*               LISTEN      659/influxd
tcp        0      0 127.0.0.1:25            0.0.0.0:*               LISTEN      792/master
tcp        0      0 0.0.0.0:111             0.0.0.0:*               LISTEN      319/rpcbind
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN      655/sshd
tcp6       0      0 :::3000                 :::*                    LISTEN      662/grafana-server
tcp6       0      0 ::1:25                  :::*                    LISTEN      792/master
tcp6       0      0 :::111                  :::*                    LISTEN      319/rpcbind
tcp6       0      0 :::8086                 :::*                    LISTEN      659/influxd
tcp6       0      0 :::22                   :::*                    LISTEN      655/sshd

3. Viewing Open UDP Socket Connections

Similar to TCP, this command shows all UDP connections currently open and active.

[root@DevopsRoles ~]# netstat -nplu
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name
udp        0      0 127.0.0.1:323           0.0.0.0:*                           313/chronyd
udp        0      0 0.0.0.0:68              0.0.0.0:*                           464/dhclient
udp        0      0 0.0.0.0:111             0.0.0.0:*                           319/rpcbind
udp        0      0 0.0.0.0:906             0.0.0.0:*                           319/rpcbind
udp6       0      0 ::1:323                 :::*                                313/chronyd
udp6       0      0 :::111                  :::*                                319/rpcbind
udp6       0      0 :::906                  :::*                                319/rpcbind

4. List all TCP Listening Ports

[root@DevopsRoles ~]# netstat -lt
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State
tcp        0      0 DevopsRoles:radan-http  0.0.0.0:*               LISTEN
tcp        0      0 DevopsRoles:smtp        0.0.0.0:*               LISTEN
tcp        0      0 0.0.0.0:sunrpc          0.0.0.0:*               LISTEN
tcp        0      0 0.0.0.0:ssh             0.0.0.0:*               LISTEN
tcp6       0      0 [::]:hbci               [::]:*                  LISTEN
tcp6       0      0 localhost:smtp          [::]:*                  LISTEN
tcp6       0      0 [::]:sunrpc             [::]:*                  LISTEN
tcp6       0      0 [::]:d-s-n              [::]:*                  LISTEN
tcp6       0      0 [::]:ssh                [::]:*                  LISTEN

4. List all UDP Listening Ports 

[root@DevopsRoles ~]# netstat -lu
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State
udp        0      0 DevopsRoles:323         0.0.0.0:*
udp        0      0 0.0.0.0:bootpc          0.0.0.0:*
udp        0      0 0.0.0.0:sunrpc          0.0.0.0:*
udp        0      0 0.0.0.0:906             0.0.0.0:*
udp6       0      0 localhost:323           [::]:*
udp6       0      0 [::]:sunrpc             [::]:*
udp6       0      0 [::]:906                [::]:*

5. Show Statistics by Protocol

[root@DevopsRoles ~]# netstat -s
Ip:
    9607 total packets received
    0 forwarded
    0 incoming packets discarded
    9605 incoming packets delivered
    4614 requests sent out
    7 outgoing packets dropped
Icmp:
    16 ICMP messages received
    0 input ICMP message failed.
    ICMP input histogram:
        destination unreachable: 16
    16 ICMP messages sent
    0 ICMP messages failed
    ICMP output histogram:
        destination unreachable: 16
IcmpMsg:
        InType3: 16
        OutType3: 16
Tcp:
    267 active connections openings
    412 passive connection openings
    2 failed connection attempts
    3 connection resets received
    3 connections established
    20699 segments received
    19546 segments send out
    66 segments retransmited
    0 bad segments received.
    13 resets sent
Udp:
    184 packets received
    16 packets to unknown port received.
    0 packet receive errors
    200 packets sent
    0 receive buffer errors
    0 send buffer errors
UdpLite:
TcpExt:
    255 TCP sockets finished time wait in fast timer
    245 delayed acks sent
    16 delayed acks further delayed because of locked socket
    Quick ack mode was activated 66 times
    6400 packet headers predicted
    2503 acknowledgments not containing data payload received
    8067 predicted acknowledgments
    TCPLossProbes: 66
    TCPLossProbeRecovery: 65
    66 DSACKs sent for old packets
    66 DSACKs received
    TCPDSACKIgnoredNoUndo: 65
    TCPRcvCoalesce: 3322
    TCPOrigDataSent: 14558
    TCPHystartTrainDetect: 7
    TCPHystartTrainCwnd: 124
IpExt:
    InNoRoutes: 2
    InOctets: 1806054
    OutOctets: 7957156
    InNoECTPkts: 9899

6. Displaying Service name with PID

[root@DevopsRoles ~]# netstat -tp
Active Internet connections (w/o servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name
tcp        0      0 DevopsRoles:ssh         gateway:52836           ESTABLISHED 2434/sshd: vagrant
tcp6       0      0 localhost:44918         localhost:d-s-n         ESTABLISHED 654/telegraf
tcp6       0      0 localhost:d-s-n         localhost:44918         ESTABLISHED 659/influxd

7. Displaying Promiscuous Mode

[root@DevopsRoles ~]# netstat -ac 6 | grep tcp
tcp        0      0 DevopsRoles:radan-http  0.0.0.0:*               LISTEN
tcp        0      0 DevopsRoles:smtp        0.0.0.0:*               LISTEN
tcp        0      0 0.0.0.0:sunrpc          0.0.0.0:*               LISTEN
tcp        0      0 0.0.0.0:ssh             0.0.0.0:*               LISTEN
tcp        0      0 DevopsRoles:ssh         gateway:52836           ESTABLISHED
tcp6       0      0 [::]:hbci               [::]:*                  LISTEN
tcp6       0      0 localhost:smtp          [::]:*                  LISTEN
tcp6       0      0 [::]:sunrpc             [::]:*                  LISTEN
tcp6       0      0 [::]:d-s-n              [::]:*                  LISTEN
tcp6       0      0 [::]:ssh                [::]:*                  LISTEN
tcp6       0      0 localhost:44918         localhost:d-s-n         ESTABLISHED
tcp6       0      0 localhost:d-s-n         localhost:44918         ESTABLISHED

8. Show Network Interface Transactions

[root@DevopsRoles ~]# netstat -i
Kernel Interface table
Iface             MTU    RX-OK RX-ERR RX-DRP RX-OVR    TX-OK TX-ERR TX-DRP TX-OVR Flg
eth0             1500    10190      0      0 0          8724      0      0      0 BMRU
lo              65536    12237      0      0 0         12237      0      0      0 LRU

9. Find Listening Programs

[root@DevopsRoles ~]# netstat -ap | grep grafana
tcp6       0      0 [::]:hbci               [::]:*                  LISTEN      662/grafana-server
unix  3      [ ]         STREAM     CONNECTED     14247    662/grafana-server

Conclusion

By following the netstat examples provided, you can effectively leverage the netstat command in Linux to gain insights into your system’s network connections. This guide aims to be a practical resource for both new and seasoned users. Thank you for choosing DevopsRoles for your learning needs!

Linux

Monitoring with Grafana InfluxDB and Telegraf

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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

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!

Linux

Influxdb getting started

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Introduction

In this tutorial, we get started with InfluxDB. we can use commands with InfluxDB. In the latter-mentioned post, I created a “telegraf” database in InfluxDB.

Let’s know if InfluxDB getting started

Now jump into InfluxDB.

[root@devopsroles.localhost ~]# influx
Connected to http://localhost:8086 version 1.7.4
InfluxDB shell version: 1.7.4
Enter an InfluxQL query
>

View a list of all the databases using the “show databases” command.

> show databases                                                                                                                                                                                                                             
name: databases
name
----
_internal
netdata
monitoring
telegraf
opentsdb
>

“_internal” is an internal InfluxDB database. To use telegraf database the “use telegraf” command:

> use telegraf                                                                                                                                                                                                                               
Using database telegraf

Now we are inside of the telegraf database. using the “show measurements” command:

> show measurements                                                                                                                                                                                                                          
name: measurements
name
----
cpu
disk
diskio
kernel
mem
processes
swap
system

Field Keys in the telegraf database.

> show field keys                                                                                                                                                                                                                            
name: cpu
fieldKey         fieldType
--------         ---------
usage_guest      float
usage_guest_nice float
usage_idle       float
usage_iowait     float
usage_irq        float
usage_nice       float
usage_softirq    float
usage_steal      float
usage_system     float
usage_user       float

name: disk
fieldKey     fieldType
--------     ---------
free         integer
inodes_free  integer
inodes_total integer
inodes_used  integer
total        integer
used         integer
used_percent float

name: diskio
fieldKey         fieldType
--------         ---------
io_time          integer
iops_in_progress integer
read_bytes       integer
read_time        integer
reads            integer
weighted_io_time integer
write_bytes      integer
write_time       integer
writes           integer

name: kernel
fieldKey         fieldType
--------         ---------
boot_time        integer
context_switches integer
entropy_avail    integer
interrupts       integer
processes_forked integer

name: mem
fieldKey          fieldType
--------          ---------
active            integer
available         integer
available_percent float
buffered          integer
cached            integer
commit_limit      integer
committed_as      integer
dirty             integer
free              integer
high_free         integer
high_total        integer
huge_page_size    integer
huge_pages_free   integer
huge_pages_total  integer
inactive          integer
low_free          integer
low_total         integer
mapped            integer
page_tables       integer
shared            integer
slab              integer
swap_cached       integer
swap_free         integer
swap_total        integer
total             integer
used              integer
used_percent      float
vmalloc_chunk     integer
vmalloc_total     integer
vmalloc_used      integer
wired             integer
write_back        integer
write_back_tmp    integer

name: processes
fieldKey      fieldType
--------      ---------
blocked       integer
dead          integer
idle          integer
paging        integer
running       integer
sleeping      integer
stopped       integer
total         integer
total_threads integer
unknown       integer
zombies       integer

name: swap
fieldKey     fieldType
--------     ---------
free         integer
in           integer
out          integer
total        integer
used         integer
used_percent float

name: system
fieldKey      fieldType
--------      ---------
load1         float
load15        float
load5         float
n_cpus        integer
n_users       integer
uptime        integer
uptime_format string

Tag Keys in the telegraf database.

> show tag keys                                                                                                                                                                                                                              
name: cpu
tagKey
------
cpu
host

name: disk
tagKey
------
device
fstype
host
mode
path

name: diskio
tagKey
------
host
name

name: kernel
tagKey
------
host

name: mem
tagKey
------
host

name: processes
tagKey
------
host

name: swap
tagKey
------
host

name: system
tagKey
------
host

InfluxDB Queries

How fields and tags work together. For example as below

> select * from cpu where time > now() - 10s                                                                                                                                                                                                 
name: cpu
time                cpu       host                         usage_guest usage_guest_nice usage_idle       usage_iowait      usage_irq usage_nice usage_softirq usage_steal usage_system        usage_user
----                ---       ----                         ----------- ---------------- ----------       ------------      --------- ---------- ------------- ----------- ------------        ----------
1557722520000000000 cpu-total devopsroles.localhost 0           0                92.4924924924855 6.106106106081209 0         0          0             0           0.30030030030030713 1.10110110109885
1557722520000000000 cpu0      devopsroles.localhost 0           0                92.4924924924855 6.106106106081209 0         0          0             0           0.30030030030030713 1.10110110109885

> select * from cpu where cpu='cpu-total' and host='devopsroles.localhost' and time > now() - 10s                                                                                                                                     
name: cpu
time                cpu       host                         usage_guest usage_guest_nice usage_idle       usage_iowait      usage_irq usage_nice usage_softirq usage_steal usage_system        usage_user
----                ---       ----                         ----------- ---------------- ----------       ------------      --------- ---------- ------------- ----------- ------------        ----------
1557727830000000000 cpu-total devopsroles.localhost 0           0                96.7967967967239 2.402402402420665 0         0          0             0           0.20020020020020476 0.6006006006006143

> select usage_user,cpu,host from cpu where cpu='cpu-total' and host='devopsroles.localhost' and time > now() - 20s                                                                                                                   
name: cpu
time                usage_user         cpu       host
----                ----------         ---       ----
1557727930000000000 1.6016016016016381 cpu-total devopsroles.localhost

Series is a “collection of data in InfluxDB’s data structure that share a measurement, tag set, and retention policy.” Thank you for reading the DevopsRoles page!

Influxdb getting started. Influxdb getting started. Influxdb getting started.

Linux

How to install Telegraf on Linux

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Introduction

Telegraf is a versatile and efficient agent for collecting and reporting metrics. It supports a wide array of data stores such as InfluxDB, Graphite, OpenTSDB, Datadog, and many more. This guide will walk you through the process of installing Telegraf on various Linux distributions, including Ubuntu and CentOS, ensuring you can get started with minimal hassle. How to install Telegraf on Linux is a step below.

Features of Telegraf

  • Supports Multiple Datastores: Compatible with InfluxDB, Graphite, OpenTSDB, Datadog, and many others.
  • Plugin-Driven: Easily extendable through numerous input and output plugins.
  • Small Memory Footprint: Designed to be lightweight and efficient.

Prerequisites

Before proceeding with the installation, ensure your system meets the following requirements:

  • A Linux distribution (Ubuntu, CentOS, Debian, etc.)
  • Root or sudo access to the system
  • Internet connection for downloading Telegraf packages

Installation Steps

RedHat & CentOS

To install Telegraf on RedHat and CentOS systems, follow these steps:

Download the Telegraf RPM package.

wget https://dl.influxdata.com/telegraf/releases/telegraf-1.10.3-1.x86_64.rpm

Install the downloaded package using yum.

sudo yum localinstall telegraf-1.10.3-1.x86_64.rpm

Verify the installation by checking the Telegraf version.

telegraf -version The output should be similar to:lessCopy codeTelegraf 1.10.3 (git: HEAD 294bb666)

Ubuntu & Debian

For Debian-based systems such as Ubuntu, follow these steps:

Download the Telegraf DEB package.

wget https://dl.influxdata.com/telegraf/releases/telegraf_1.10.3-1_amd64.deb

Install the downloaded package using dpkg.

sudo dpkg -i telegraf_1.10.3-1_amd64.deb

OS X (via Homebrew)

For macOS users, Telegraf can be installed using Homebrew:

  1. Update Homebrew. brew update
  2. Install Telegraf. brew install telegraf

Starting the Telegraf Service

After installing Telegraf, you need to start and enable the service.

  1. Start the Telegraf service. sudo systemctl start telegraf
  2. Enable the Telegraf service to start on boot. sudo systemctl enable telegraf

Configuration

Telegraf’s configuration file is located at /etc/telegraf/telegraf.conf. This file defines how Telegraf collects and outputs data.

Basic Configuration

Open the configuration file in your preferred text editor.

sudo nano /etc/telegraf/telegraf.conf

Input Plugins

Enable the CPU input plugin by adding the following configuration:

[[inputs.cpu]]
  percpu = true
  totalcpu = true
  collect_cpu_time = false
  report_active = false

Output Plugins

To output data to InfluxDB, configure the output plugin as follows:

[[outputs.influxdb]]
  urls = ["http://localhost:8086"]
  database = "telegraf"
  retention_policy = ""
  write_consistency = "any"
  timeout = "5s"

Advanced Configuration

Adding Custom Plugins

You can extend Telegraf’s functionality by adding custom plugins. Place your custom plugin scripts in the appropriate directory and reference them in the configuration file.

Using Environment Variables

Telegraf supports environment variables, which can be useful for managing configurations in different environments.

Securing Telegraf

Ensure Telegraf is secure by:

  • Running it with the least privileges necessary.
  • Using HTTPS for data transmission.
  • Regularly updating to the latest version.

Troubleshooting

Common Issues

  • Service not starting: Check the system logs for errors using journalctl -u telegraf.
  • Data not collected: Ensure the input plugins are correctly configured.
  • Data not sent: Verify the output plugin configuration and network connectivity.

Useful Commands

  • Check the configuration: telegraf --config /etc/telegraf/telegraf.conf --test
  • View logs: sudo journalctl -u telegraf

Frequently Asked Questions (FAQs)

What is Telegraf used for?

Telegraf is used for collecting, processing, and writing metrics and events from various sources to various outputs.

Can Telegraf run on Windows?

Yes, Telegraf is cross-platform and can run on Windows, macOS, and Linux.

How do I update Telegraf?

To update Telegraf, simply follow the installation steps again, as the package manager will handle the upgrade process.

Is Telegraf free to use?

Yes, Telegraf is open-source and free to use under the MIT license.

Conclusion

Installing Telegraf on Linux is a straightforward process when you follow the right steps. From basic installation to advanced configuration, this guide has covered everything you need to get started with Telegraf. By leveraging its powerful features, you can efficiently collect and manage metrics for your infrastructure. Whether you’re a beginner or an advanced user, Telegraf offers the flexibility and scalability needed for effective monitoring.

Start your journey with Telegraf today and ensure your system’s performance is always at its peak! Thank you for reading the DevopsRoles page!

Linux

Grafana reset admin password

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Introduction

I have forgotten the password admin Grafana dashboard. Yesterday, I can not log in to my Grafana dashboard. I have searched google and reset the Admin password in Grafana. Now, let’s go Grafana reset admin password.

Grafana is a powerful open-source platform for monitoring and observability. Its user-friendly dashboards make it a favorite among DevOps teams and system administrators. However, there may be situations where you need to reset the admin password, such as forgotten credentials or initial setup. In this comprehensive guide, we’ll cover everything you need to know about resetting the admin password in Grafana, from basic commands to advanced security practices.

Why Resetting the Admin Password Is Essential

Resetting the admin password in Grafana is necessary in scenarios like:

  • Forgotten Admin Credentials: If the admin password is lost, resetting it ensures access to the platform.
  • Security Maintenance: Resetting passwords regularly minimizes the risk of unauthorized access.
  • Initial Setup Needs: During initial configuration, resetting the default password enhances security.

Grafana provides multiple ways to reset the admin password, catering to different environments and user needs. Let’s dive into these methods step-by-step.

How do I Grafana reset admin password

Log in to the database

$ sudo sqlite3 /var/lib/grafana/grafana.db

Reset the admin password to “admin”

sqlite> update user set password = '59acf18b94d7eb0694c61e60ce44c110c7a683ac6a8f09580d626f90f4a242000746579358d77dd9e570e83fa24faa88a8a6', salt = 'F3FAxVm33R' where login = 'admin';
sqlite> .quit

Now you can log in using these credentials:

  • username: admin
  • password: admin

FAQs on Grafana Reset Admin Password

1. What happens if I reset the admin password?

Resetting the admin password updates the login credentials for the admin user only. Other user accounts and settings remain unaffected.

2. Can I reset the password without restarting Grafana?

No, most methods require restarting the Grafana service to apply changes.

3. Is the grafana-cli command available for all installations?

The grafana-cli tool is available in standard installations. If it’s missing, verify your installation method or use alternative methods.

4. How can I hash passwords for SQL resets?

Use a tool like openssl or online SHA256 hashing tools to generate a hashed password.

5. Is it possible to automate password resets?

Yes, you can automate resets using scripts that interact with grafana-cli or directly modify the database.

Additional Resources

Conclusion

Resetting the admin password in Grafana is a straightforward process, whether using the grafana-cli command, editing the configuration file, or updating the database directly. By following this guide, you can efficiently regain access to your Grafana instance and secure it against unauthorized access. Remember to adopt best practices for password management to maintain a robust security posture.

You have reset admin password Grafana dashboard. Afterward, you need to change the admin password. Thank you for reading the DevopsRoles page!

Linux

Step by step Install JDK on CentOS

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In this tutorial, How to Install JDK on CentOS step by step. How to switch between JDK 7 and JDK 8?

Precondition

  1. Open the terminal and log in as root or you use sudo before each command with another user.
  2. Working on a Linux system operating: Centos/REHL

Search for JDK on CentOS

You use the command below to search the packages

$ yum search openjdk

The output terminal console as below

Install JDK 1.8

$ sudo yum install java-1.8.0-openjdk

Confirmation is complete when the installed Java version is displayed.

$ java --version
# Output
# openjdk version "1.8.0_212"
# OpenJDK Runtime Environment (build 1.8.0_212-b04)
# OpenJDK 64-Bit Server VM (build 25.212-b04, mixed mode)

How to switch JDK 7 to JDK 8

Use the command “sudo alternatives –config java” to switch to JDK.

How to switch JDK 8 to JDK 7

Conclusion

Through the article,  How to Install JDK on CentOS step by step. How to switch between JDK 7 and JDK 8? as above. I hope will this your helpful. Thank you for reading the DevopsRoles page!

Linux

Install Grafana on Centos 7

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Grafana is tool monitoring and Data visualization with support InfluxDB, Graphite, Prometheus, Elasticsearch, and many more databases.

In this tutorial, How to install Grafana on Linux. Link download manually here

Install Grafana on Centos 7

Add Grafana yum repository

[vagrant@DevopsRoles ~]$ cat <<EOF | sudo tee /etc/yum.repos.d/grafana.repo
[grafana]
name=grafana
baseurl=https://packages.grafana.com/oss/rpm
repo_gpgcheck=1
enabled=1
gpgcheck=1
gpgkey=https://packages.grafana.com/gpg.key
sslverify=1
sslcacert=/etc/pki/tls/certs/ca-bundle.crt
EOF

Update cache index as below

[vagrant@DevopsRoles ~]$ sudo yum makecache

Install Grafana

[vagrant@DevopsRoles ~]$ sudo yum -y install grafana

Start Grafana service

[vagrant@DevopsRoles ~]$ sudo systemctl enable --now grafana-server.service

The default port of Grafana used is 3000

Grafana write logs to /var/log/grafana directory and its SQLite database is located under /var/lib/grafana/grafana.db

Open firewall port for Grafana

[vagrant@DevopsRoles ~]$ sudo firewall-cmd --add-port=3000/tcp --permanent
[vagrant@DevopsRoles ~]$ sudo firewall-cmd --reload

Access Grafana Dashboard on Centos 7

Grafana web dashboard on http://[Server IP|Hostname]:3000

The default login as below

username: admin
Password: admin

The change password first login as below

You have Installed Grafana on Centos 7. Thank you for reading the DevopsRoles page!

Linux

Install nslookup on Linux

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Introduction

In this tutorial, How to install on Linux. is part of the bind-utils package. The package bind-utils is not yet installed on Linux, then you type command not found on Linux.

To install nslookup on Linux, you need to install the dnsutils package, which contains the nslookup utility. The process for installing the package can vary depending on the Linux distribution you are using. Here are the commands for some popular distributions:

How to Install nslookup on Linux

Install nslookup for Centos

[vagrant@DevopsRoles ~]$ sudo yum install bind-utils

Install nslookup for Ubuntu

Use apt-cache to search the package for nslookup command.

[vagrant@DevopsRoles ~]$ apt-cache search nslookup

The result found 2 packages that are related to nslookup.

dnsutils - Clients provided with BIND
libnet-nslookup-perl - simple DNS lookup module for perl

so install nslookup

[vagrant@DevopsRoles ~]$ sudo apt-get install dnsutils

Once the installation is complete, you can use nslookup from the command line.

[vagrant@DevopsRoles ~]$ nslookup x.x.x.x

Conclusion

In this guide, we have covered how to install and use the nslookup command on Linux, specifically for CentOS and Ubuntu. Whether you’re troubleshooting DNS issues or simply querying domain name records, nslookup is a powerful and essential tool for network administrators and IT professionals.

By following the simple installation steps, you can quickly enable nslookup on your system and start resolving domain names with ease. If you encounter any issues, ensure that your system’s package manager is up to date and that you have the necessary permissions to install packages.

We hope this guide has been helpful! If you have any questions or need further assistance, feel free to leave a comment or check out our other Linux tutorials. Thank you for reading the DevopsRoles page!

Linux

Install Prometheus on RHEL / CentOS 7

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In this tutorial, How to install Prometheus on RHEL / CentOS 7. Prometheus is an open-source applications and microservices. Prometheus releases Github

Install Prometheus

Create user and group Prometheus system

sudo groupadd --system prometheus
sudo useradd -s /sbin/nologin --system -g prometheus prometheus

Create the data directory for Prometheus

sudo mkdir /var/lib/prometheus

Prometheus creates the configuration directory

sudo mkdir -p -m 775 /etc/prometheus/{rules,rules.d,files_sd}

Download and extract Prometheus

cd /tmp
export RELEASE=2.8.1
wget https://github.com/prometheus/prometheus/releases/download/v${RELEASE}/prometheus-${RELEASE}.linux-amd64.tar.gz
tar xvf prometheus-${RELEASE}.linux-amd64.tar.gz
cd prometheus-${RELEASE}.linux-amd64/

Copy Prometheus binary, consoles and console_libraries

sudo cp prometheus promtool /usr/local/bin/
sudo cp -r consoles/ console_libraries/ /etc/prometheus/

Create a Prometheus configuration file.

sudo vi /etc/prometheus/prometheus.yml

The content as below

# Global config
global: 
  scrape_interval:     15s # Set the scrape interval to every 15 seconds. Default is every 1 minute.  
  evaluation_interval: 15s # Evaluate rules every 15 seconds. The default is every 1 minute.  
  scrape_timeout: 15s  # scrape_timeout is set to the global default (10s).

# A scrape configuration containing exactly one endpoint to scrape:# Here it's Prometheus itself.
scrape_configs:
  # The job name is added as a label `job=<job_name>` to any timeseries scraped from this config.
  - job_name: 'prometheus'

    # metrics_path defaults to '/metrics'
    # scheme defaults to 'http'.

    static_configs:
    - targets: ['localhost:9090']

Create a Prometheus systemd service unit file.

sudo vi /etc/systemd/system/prometheus.service

The content Prometheus systemd service as below

[Unit]
Description=Prometheus
Documentation=https://prometheus.io/docs/introduction/overview/
Wants=network-online.target
After=network-online.target

[Service]
Type=simple
Environment="GOMAXPROCS=2"
User=prometheus
Group=prometheus
ExecReload=/bin/kill -HUP $MAINPID
ExecStart=/usr/local/bin/prometheus \
  --config.file=/etc/prometheus/prometheus.yml \
  --storage.tsdb.path=/var/lib/prometheus \
  --web.console.templates=/etc/prometheus/consoles \
  --web.console.libraries=/etc/prometheus/console_libraries \
  --web.listen-address=0.0.0.0:9090 \
  --web.external-url=

SyslogIdentifier=prometheus
Restart=always

[Install]
WantedBy=multi-user.target

Note: You remember to edit the line: Environment=”GOMAXPROCS=2 with replacing 2 is the number of vcpus on the server.

Clean install

rm -rf prometheus-${RELEASE}.linux-amd64.tar.gz
rm -rf prometheus-${RELEASE}.linux-amd64/

Change directory permission.

sudo chown -R prometheus:prometheus /etc/prometheus
sudo chown -R prometheus:prometheus /var/lib/prometheus/

Reload systemd daemon and start the Prometheus service

sudo systemctl daemon-reload
sudo systemctl start prometheus

Configure firewalld

sudo firewall-cmd --permanent --add-rich-rule 'rule family="ipv4" \
source address="192.168.10.0/24" port protocol="tcp" port="9090" accept'
sudo firewall-cmd --reload

Test access Prometheus service on port 9090

$ telnet localhost 9090

Access Prometheus Web dashboard on server

You have to install Prometheus on your system! You got it. Thank you for reading the DevopsRoles page!

Linux

Install InfluxDB on RHEL / Centos 7

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In this tutorial, How to install InfluxDB on RHEL / Centos 7. InfluxDB is an open-source time-series database. It is High availability storage and optimized for fast and metrics analysis.

To install InfluxDB on RHEL/CentOS 7, you can follow the steps below:

Install InfluxDB on RHEL / Centos 7

First, You add InfluxDB repository to your system using the command below

[vagrant@DevopsRoles ~]$ sudo vi  /etc/yum.repos.d/influxdb.repo

Add the content below:

[influxdb]
name = InfluxDB Repository
baseurl = https://repos.influxdata.com/rhel/7/x86_64/stable/
enabled = 1
gpgcheck = 1
gpgkey = https://repos.influxdata.com/influxdb.key

Install InfluxDB

[vagrant@DevopsRoles ~]$ sudo yum -y install influxdb

Enable the InfluxDB service to start on system boot:

[vagrant@DevopsRoles ~]$ sudo systemctl enable influxdb

Start InfluxDB services on RHEL / Centos 7

[vagrant@DevopsRoles ~]$ sudo systemctl start influxdb

To check the status of InfluxDB is running

[vagrant@DevopsRoles ~]$ sudo systemctl status influxdb

Configure InfluxDB Firewall on RHEL / Centos 7

The default, InfluxDB uses TCP port 8086 for client-server communication over HTTP API, and TCP port 8088 is used for backup and restore.

Open the port on the Firewall using the command below

[vagrant@DevopsRoles ~]$ sudo firewall-cmd --add-port=8086/tcp --permanent
[vagrant@DevopsRoles ~]$ sudo firewall-cmd --reload

Configure InfluxDB HTTP Authentication on RHEL / Centos 7

Enable HTTP authentication

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

Add the content below:

[http]
 auth-enabled = true

Restart the InfluxDB service.

[vagrant@DevopsRoles ~]$ sudo systemctl restart influxdb

Create a user with an Authentication password

[vagrant@DevopsRoles ~]$ curl -XPOST "http://localhost:8086/query" --data-urlencode "q=CREATE USER \
username WITH PASSWORD 'password' WITH ALL PRIVILEGES"

You need to run any Influxdb commands on the terminal with a specific username and password.

[vagrant@DevopsRoles ~]$ influx -username 'username' -password 'password'

For example, the curl command uses the -u option to specify a username and password.

[vagrant@DevopsRoles ~]$ curl -G http://localhost:8086/query -u username:password --data-urlencode "q=SHOW DATABASES"

Check Influxdb service is listening

[vagrant@DevopsRoles ~]$ sudo netstat -nplt | grep 8086

You have successfully installed InfluxDB on RHEL/CentOS 7. Thank you for reading the DevopsRoles page!