This tutorial will provide you with a quick and easy way to setup DKIM (DomainKeys) with the Postfix Mail server running on Ubuntu and Debian-based systems.

Prerequisites

Before we install and configure OpenDKIM for Postfix, we need to make sure that we have the necessary prerequisites in place.

• First and foremost, you will need a working Ubuntu system with root access.
• You will also need to have Postfix installed and configured.
• The last prerequisite is that you should have a valid domain name with DNS access.

Without these prerequisites in place, you will not be able to install and configure OpenDKIM on your server.

Step 1: Install Opendkim Package

Once you have all the prerequisites in place, you can start installing OpenDKIM. We will be using the apt package manager to install OpenDKIM on Ubuntu. To install OpenDKIM, you will need to run the following command:

sudo apt update 
sudo apt install opendkim opendkim-tools 

Then add the postfix user to the opendkim group.

sudo usermod -G opendkim postfix

Step 2: Generate Public and Private DKIM Keys

The next step is to create a proper directory structure to keep the Key files secure. Run the following commands to create a directory and set permissions.

sudo mkdir -p /etc/opendkim/keys 
sudo chown -R opendkim:opendkim /etc/opendkim
sudo chmod  744 /etc/opendkim/keys 

Now, generate your public and private DKIM keys using opendkim-genkey command line utility. All the commands are using “example.com” as a domain name. Replace it with your real domain name. We also need to choose a selector name, This can be any unique string, that helps Mail servers to identify the correct DKIM key from the DNS record. Below command will use default as selector key:

sudo mkdir /etc/opendkim/keys/example.com 
sudo opendkim-genkey -b 2048 -d example.com -D /etc/opendkim/keys/example.com -s default -v 

This command will generate a public and private key pair for you. The private key will be stored in the file “selector.private”, and the public key will be stored in the file “selector.txt”. In our case, The filenames are “default.private” and “default.txt”.

Once you have generated the keys, you will need to set appropriate permissions on the private key file:

sudo chown opendkim:opendkim /etc/opendkim/keys/example.com/default.private

Step 3: Setup DKIM Keys to Your DNS Record

Once you have generated the public and private DKIM keys, you will need to add them to your DNS record. To do this, you will need to add the TXT record to your DNS zone file. This record detail can be found under the default.txt file, generate with the private key:

sudo cat /etc/opendkim/keys/example.com/default.txt

You will see the output below:

default._domainkey      IN      TXT     ( "v=DKIM1; h=sha256; k=rsa; "
          "p=MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAwC/i/W8cVs5610MpSw1DmRWr5Dh7979SBpmSBpdzmKxyRr1S8hwapB2wWypouxS1RP3s9eEW9Oek2eKNAySZUvb6vQgUP+EK5sBuNe/bR4yvyc9pH9+eR2qvEmky4xksSNaS34F74ZUshwV1QSn8eG/5lTrxJD5TUv3/AymqsmOyT5ya9ga0smNtz+3yP9zAbMsGysnVFS2EQN"
          "9fIUc3S7tqpN9FJhcZG7DVfqcMNUDP7q+9cbu/i9UoFmRbuQW3em1JSGFnu0IwRfnmgPvH4dwjLL9DzXkC576RusuFiDjXzgOtTn/KOHUJ1MoF/vp52hwi+QZPPRfF3ILZbe/+0wIDAQAB" )  ; ----- DKIM key default for tecadmin.net

Remove all the quotes (“) and blank spaces from the record value, then publish it to the DNS zone. See the below screenshot:

You can verify the DNS record by running the following command.

sudo opendkim-testkey -d example.com -s default -vvv 

Step 4: Confiugring OpenDKIM

Once OpenDKIM has been installed and you have generated the DKIM public-private keys. you will need to configure it. To do this, you will need to edit the configuration file located at /etc/opendkim.conf. In this file, you will need to set the following parameters:

1. Edit the main configuration file in your favorite text editor:

   sudo nano /etc/opendkim.conf 
   

2. Uncomment these values and configure as below:

   Syslog                  	yes
   LogWhy                 		yes 
   
   Canonicalization        	relaxed/simple
   Mode                    	sv
   SubDomains              	no
   OversignHeaders         	From
   

   The LogWhy option enables the more detailed logs for troubleshooting:

3. Now add the following values

   AutoRestart			yes
   AutoRestartRate			10/1M
   Background			yes
   DNSTimeout			5
   SignatureAlgorithm		rsa-sha256
   

   

4. Next make sure that UserID is set to opendkim:

   # Remember to add user postfix to group opendkim
   UserID             opendkim
   

5. Now, append the following entries to the end of the file.

   KeyTable            refile:/etc/opendkim/key.table
   SigningTable        refile:/etc/opendkim/signing.table
   ExternalIgnoreList  /etc/opendkim/trusted.hosts
   InternalHosts       /etc/opendkim/trusted.hosts
   

6. Save and close /etc/opendkim.conf configuration file.
7. Now, edit the SigningTable in text editor.

   sudo nano /etc/opendkim/signing.table 
   

   Add the following entries.

   *@example.com    default._domainkey.example.com
   *@*.example.com    default._domainkey.example.com
   

   Save and close the file.

8. Next, edit the KeyTable file:

   sudo nano /etc/opendkim/key.table 
   

   Add the following entry.

   default._domainkey.example.com     example.com:default:/etc/opendkim/keys/example.com/default.private
   

   Save the file and close it.

9. Next, edit the trusted.hosts file:

   sudo nano /etc/opendkim/trusted.hosts 
   

   Add your domain name and localhost entries to the newly created file. This tells OpenDKIM that if an email is coming from localhost or from the same domain, then OpenDKIM should only sign the email but ignore the DKIM verification.

   127.0.0.1
   localhost
   
   .example.com
   

   Save and close the file.

10. Restart OpenDKIM Service

    sudo systemctl restart opendkim 
    

Step 5: Configure Postfix With OpenDKIM

The next step is to configure Postfix to use OpenDKIM.

1. First we will change OpenDKIM socket file location. Lets create a new directory with the following commands:

   sudo mkdir /var/spool/postfix/opendkim 
   sudo chown opendkim:postfix /var/spool/postfix/opendkim 
   

2. Now edit the OpenDKIM configuration file in a text editor:

   sudo nano /etc/opendkim.conf 
   

   Search for the Socket entry and update it as following:

   Socket    local:/var/spool/postfix/opendkim/opendkim.sock
   

3. Next edit the /etc/default/opendkim file:

   sudo nano /etc/default/opendkim 
   

   And set the SOCKET entry as below:

   SOCKET="local:/var/spool/postfix/opendkim/opendkim.sock"
   

4. Next, you will need to edit the configuration file located at /etc/postfix/main.cf. In this file, you will need to add the following parameters:
   • milter_default_action – This is the default action to be taken when a message is received.
   • milter_protocol – This is the protocol to be used when communicating with OpenDKIM.
   • smtpd_milters – This is the list of milters that Postfix will use.

   sudo nano /etc/postfix/main.cf 
   

   Add the following lines at the end of this file, so Postfix will be able to call OpenDKIM via the milter protocol.

   # Milter configuration
   milter_default_action = accept
   milter_protocol = 6
   smtpd_milters = local:opendkim/opendkim.sock
   non_smtpd_milters = $smtpd_milters
   

5. Once you have added the parameters, you will need to restart the OpenDKIm and Postfix services. To do this, you will need to run the following command:

   sudo systemctl restart opendkim 
   sudo systemctl restart postfix 
   

   This command will restart the both service, and you will be ready to send emails using OpenDKIM.

Step 6: Test DKIM

Send an email from system terminal as below:

mail -s "Welcome home" your_email@example.com 
cc:
Your email content goes here

Press CTRL+D to sent the email and get the terminal back. Watch the log files, On successful setup, you will see an log entry

Check the email source. I have used my personal Gmail account to test this setup. I have received emails with the following header.

You can follow our next article, to create a DMARC record for your domain.

Conclusion

In this step-by-step guide, I have shown you how to install and configure OpenDKIM with Postfix on Ubuntu. I have also shown you how to generate the necessary public and private DKIM keys, and add them to your DNS record. Finally, I have shown you how to configure Postfix to use OpenDKIM. So, if you are looking to secure and protect your email traffic, DKIM is a great tool to use. Give it a try, and unleash the power of DKIM!

If this article helped you out and you want to know more about OpenDKIM, you should check out our other articles on the topic. We have detailed guides on how to install and configure OpenDKIM on various platforms, as well as troubleshooting tips and best practices. So, make sure to check them out!

The post A Step-by-Step Guide to Installing OpenDKIM with Postfix on Ubuntu – Unleash the Power of DKIM! appeared first on TecAdmin.

What is a Fedora Version?

The version of Fedora you’re using tells you a lot about the state of the software that comes with the operating system. That’s because the version number corresponds to the date of release, and not the date of the last update. This means that you can find out when the operating system was first launched by looking at the version number. When you upgrade your Fedora version, you’re taking advantage of the latest software and security fixes. You can also switch to a different release channel, which we look at later in this article. This can be helpful if you’re in an organization where software updates are managed centrally.

Tips Before Upgrading Your Fedora Version

• We recommend that you perform a full backup of your system before you upgrade your Fedora version. This way, you can easily restore your data if something goes wrong with the upgrade. We also recommend that you check the release notes of the new version before you start the upgrade process. These notes will tell you what new features you can expect and any potential issues that you might run into.
• Before you can upgrade your Fedora version, you have to make sure you have enough space on your hard drive. This is because the upgrade process downloads the ISO file for the new version and installs it alongside the version you’re currently using. It then uses some clever technology to make sure you can toggle between the two versions.

You can upgrade to the latest version of Fedora using either the graphical user interface or the command line. We recommend using the graphical user interface method for the Fedora workstation and using the DNF command line upgrade plugin for Fedora servers.

Upgrading Fedora Workstation (GUI)

The Fedora Workstations are recommended to upgrade using the graphical user interface. Once a new Fedora version is available to upgrade, you will get a notification on the screen.

1. Then you should go to the Fedora Software section and open the Updates pane. Here you will find the notification of the latest version. Next click the Download button as shown in below screen:
   

   

2. Once the download is finished, you will get a Restart & Update button. Just click this button to continue the upgrade process. This will reboot your system and complete the Fedora Upgrade.
   

   

Wait for the Fedora upgrade process complete. You can utilize this time with other tasks or have a cup of coffee. Once the upgrade is finished, log in to the Fedora system and check the version.

Upgrade Fedora Using DNF (CLI)

The System upgrade is only officially tested over the 2 previous releases. For example, if the latest Fedora version is 36 then you should upgrade to this version from 35 and 34. If the Fedora version is older than 2 releases, it is recommended to do it in several smaller steps. You can find the current Fedora version with the following commands.

cat /etc/fedora-release 

Fedora release 35 (Thirty Five)

You can visit the official website to find the latest Fedora version details. Then follow the below instructions to upgrade Fedora version:

1. Uprade current packages on your system. To do this open a terminal and type:

   sudo dnf --refresh upgrade 
   

   This will take a long time as per the available packages to upgrade.

2. The dnf-plugin-system-upgrade is a plugin for the DNF package manager. Which is used to upgrade fedora systems quickly.

   sudo dnf install dnf-plugin-system-upgrade --best 
   

3. Once you have installed the plugin. Now download the latest packages of Fedora 36.

   sudo dnf system-upgrade download --refresh --releasever=36 
   

4. This will start the final upgrade process to get Fedora 36 on your system.

   dnf system-upgrade reboot 
   

   This will reboot your Fedora system and start the upgrade process. You will see a process bar like the below screenshot:

   The upgrade process takes time. Have a cup of coffee and be relaxed until the upgrade is complete.

Post Upgrade Tasks (Optional)

Once the system is upgraded successfully to the latest Fedora version. Rebuild the rpm database with the following command.

rpm --rebuilddb 

Also perform the Distro Sync on your latest Fedora version.

dnf distro-sync --setopt=deltarpm=0 

Conclusion

Nowadays, there is nothing better than using Linux because it has many benefits that are not available to users using other operating systems. One of the best things about using Linux is that you can easily upgrade the version of this operating system between different releases. Many users often wonder how they can upgrade the version of their Linux operating system because this process can be done easily. This article explains how you can upgrade the version of your Fedora Linux operating system.

Reference:
https://docs.fedoraproject.org/en-US/quick-docs/dnf-system-upgrade/

The post Upgrade Fedora: A Step-by-Step Guide For Beginners appeared first on TecAdmin.

Prerequisites

• Shell access to a running Ubuntu system.
• Install PHP 5.3 or higher version.
• PHP’s package manager, `php-cli`, must be installed and available in your `PATH`

Installing PHP Composer on Ubuntu

The Composer’s official team provides a script to install PHP composer on Linux systems. You can download this script using the `curl` or `wget` command-line utility. Also, you can download it directly using the PHP script command line.

1. To download the `composer-setup` script, run the following command in a terminal:

   php -r "copy('https://getcomposer.org/installer', 'composer-setup.php');" 
   

2. Then execute the downloaded PHP script to install the composer on your Ubuntu system at the desired location. Use --install-dir to set the binary location and --filename to set the binary name. You can choose one of the below option:
   • Installing PHP composer system-wide: This will install composer in /uer/local/bin directory, that is accessible to all users:

     sudo php composer-setup.php --install-dir=/usr/local/bin --filename=composer
     sudo chmod +x /usr/local/bin/composer
     

   • Installing PHP composer for specific applicaiton: Sometimes you dont’ have permission to install it globally, like shared hosting account. Then you can configure this under you application as well. To install composer locally type:

     cd /path/to/php-application && mkdir -p bin 
     php composer-setup.php --install-dir=bin --filename=composer
     chmod +x bin/composer
     

     Make sure to replace /path/to/php-application with your application directory.

3. To see the installed composer version execute binary with -v command parameter.

   composer --version
   

   Output:
   Composer version 2.3.7 2022-06-06 16:43:28
   

Upgrade PHP Composer

The PHP composer has the ability to self-upgrade to the latest versions. If the composer is already installed on your system, just type the below command to upgrade the PHP composer to the latest version.

composer self-update

In my case, I already have latest version of composer. So receive the following message on terminal:

Output:
You are already using the latest available Composer version 2.3.7 (stable channel).

Working with PHP Composer

You have already installed and configured the composer on your system. The composer will help you to manage modules for your application. For example, to install a new module for your application.

Switch to the PHP application.

cd /path/to/php-application 

Run the following command to install psr/log module in the application.

composer require psr/log

Output:
Using version ^3.0 for psr/log
./composer.json has been created
Running composer update psr/log
Loading composer repositories with package information
Updating dependencies
Lock file operations: 1 install, 0 updates, 0 removals
  - Locking psr/log (3.0.0)
Writing lock file
Installing dependencies from lock file (including require-dev)
Package operations: 1 install, 0 updates, 0 removals
  - Downloading psr/log (3.0.0)
  - Installing psr/log (3.0.0): Extracting archive
Generating autoload files

Composer will automatically create or update composer.json file at application root directory. Now, the application can use the functionality provided by the module.

The above command will install the latest version of the module. You can also define the module version you want to install for your application. If the module is already installed, it will automatically downgrade/upgrade the package to the specified version.

composer require psr/log=1.0

The module no longer required can be removed with the following command.

composer remove psr/log

All the above commands also update composer.json file accordingly.

Conclusion

In this article, we have covered the steps for installing Composer on Ubuntu 22.04. By using Composer, you can easily manage the dependencies of your PHP projects and ensure that all necessary libraries are installed and up to date. Whether you are new to PHP development or an experienced developer, Composer can help you streamline your workflow and improve the quality of your projects.

The post How to Install Composer on Ubuntu 22.04 appeared first on TecAdmin.

This tutorial provides you with step-by-step instructions to install Apache Kafka on Ubuntu 22.04 LTS Linux system. You will also learn to create topics in Kafka and run producer and consumer nodes.

Prerequisites

You must have sudo privileged account access to the Ubuntu 22.04 Linux system.

Step 1 – Installing Java

We can run the Apache Kafka server on systems that support Java. So make sure, you have Java installed on your Ubuntu system.

Use the following commands to install OpenJDK on your Ubuntu system from the official repositories.

sudo apt update  
sudo apt install default-jdk 

Verify the current active Java version.

java --version 

Output:
openjdk version "11.0.15" 2022-04-19
OpenJDK Runtime Environment (build 11.0.15+10-Ubuntu-0ubuntu0.22.04.1)
OpenJDK 64-Bit Server VM (build 11.0.15+10-Ubuntu-0ubuntu0.22.04.1, mixed mode, sharing)

Step 2 – Download Latest Apache Kafka

You can download the latest Apache Kafka binary files from its official download page. Alternativaly you can download Kafka 3.2.0 with the below command.

wget https://dlcdn.apache.org/kafka/3.2.0/kafka_2.13-3.2.0.tgz 

Then extract the downloaded archive file and place them under /usr/local/kafka directory.

tar xzf kafka_2.13-3.2.0.tgz 
sudo mv kafka_2.13-3.2.0 /usr/local/kafka 

Step 3 – Create Systemd Startup Scripts

Now, create systemd unit files for the Zookeeper and Kafka services. That will help you to start/stop the Kafka service in an easy way.

First, create a systemd unit file for Zookeeper:

sudo nano /etc/systemd/system/zookeeper.service 

And add the following content:

[Unit]
Description=Apache Zookeeper server
Documentation=http://zookeeper.apache.org
Requires=network.target remote-fs.target
After=network.target remote-fs.target

[Service]
Type=simple
ExecStart=/usr/local/kafka/bin/zookeeper-server-start.sh /usr/local/kafka/config/zookeeper.properties
ExecStop=/usr/local/kafka/bin/zookeeper-server-stop.sh
Restart=on-abnormal

[Install]
WantedBy=multi-user.target

Save the file and close it.

Next, create a systemd unit file for the Kafka service:

sudo nano /etc/systemd/system/kafka.service 

Add the below content. Make sure to set the correct JAVA_HOME path as per the Java installed on your system.

[Unit]
Description=Apache Kafka Server
Documentation=http://kafka.apache.org/documentation.html
Requires=zookeeper.service

[Service]
Type=simple
Environment="JAVA_HOME=/usr/lib/jvm/java-11-openjdk-amd64"
ExecStart=/usr/local/kafka/bin/kafka-server-start.sh /usr/local/kafka/config/server.properties
ExecStop=/usr/local/kafka/bin/kafka-server-stop.sh

[Install]
WantedBy=multi-user.target

Save the file and close.

Reload the systemd daemon to apply new changes.

sudo systemctl daemon-reload 

This will reload all the systemd files in the system environment.

Step 4 – Start Zookeeper and Kafka Services

Let’s start both services one by one. First, you need to start the ZooKeeper service and then start Kafka. Use the systemctl command to start a single-node ZooKeeper instance.

sudo systemctl start zookeeper 
sudo systemctl start kafka 

Verify both of the services status:

sudo systemctl status zookeeper 
sudo systemctl status kafka 

That’s it. You have successfully installed the Apache Kafka server on Ubuntu 22.04 system. Next, we will create topics in the Kafka server.

Step 5 – Create a Topic in Kafka

Kafka provides multiple pre-built shell script to work on it. First, create a topic named “testTopic” with a single partition with single replica:

cd /usr/local/kafka 
bin/kafka-topics.sh --create --bootstrap-server localhost:9092 --replication-factor 1 --partitions 1 --topic testTopic 

Output
Created topic testTopic.

Here:

• Use --create option to create a new topic
• The --replication-factor describes how many copies of data will be created. As we are running with a single instance keep this value 1.
• Set the --partitions options as the number of brokers you want your data to be split between. As we are running with a single broker keep this value 1.
• The --topic define the name of the topic

You can create multiple topics by running the same command as above. After that, you can see the created topics on Kafka by the running below command:

bin/kafka-topics.sh --list --bootstrap-server localhost:9092 

The output looks like the below screenshot:

Alternatively, instead of manually creating topics you can also configure your brokers to auto-create topics when a non-existent topic is published to.

Step 6 – Send and Receive Messages in Kafka

The “producer” is the process responsible for put data into our Kafka. The Kafka comes with a command-line client that will take input from a file or from standard input and send it out as messages to the Kafka cluster. The default Kafka sends each line as a separate message.

Let’s run the producer and then type a few messages into the console to send to the server.

bin/kafka-console-producer.sh --broker-list localhost:9092 --topic testTopic 

>Welcome to kafka
>This is my first topic
>

You can exit this command or keep this terminal running for further testing. Now open a new terminal to the Kafka consumer process on the next step.

Kafka also has a command-line consumer to read data from the Kafka cluster and display messages to standard output.

bin/kafka-console-consumer.sh --bootstrap-server localhost:9092 --topic testTopic --from-beginning 

Welcome to kafka
This is my first topic

Now, If you have still running Kafka producer in another terminal. Just type some text on that producer terminal. it will immediately be visible on the consumer terminal. See the below screenshot of Kafka producer and consumer in working:

Conclusion

This tutorial helped you to install and configure the Apache Kafka server on an Ubuntu 22.04 Linux system. Additionally, you learned to create a new topic in the Kafka server and run a sample production and consumer process with Apache Kafka.

The post How to Install Apache Kafka on Ubuntu 22.04 appeared first on TecAdmin.

You can set the environment variables in 3 ways:

1. Using the export command
2. Using /etc/environment file
3. Adding shell script under /etc/profile.d/ directory

Now we will discuss the above methods to set environment variables on Ubuntu systems one by one.

1. Using the export command

You can use the export command on the terminal to set the environment variables temporarily. That variable will be accessible on the same terminal only. Once you close the terminal the variable will be destroyed.

To set the environment variable, run:

export MY_ENV=value 

To print the MY_ENV environment variable, type:

echo $MY_ENV

2. Using /etc/enviroment file

The /etc/environment is a system-wide configuration file used for setting the environment variables. It is not a shell script, it consists of the assignment expressions, that set the environment variables one per line.

sudo vim /etc/environment

/etc/environment 
PATH="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin"
JAVA_HOME=/usr/lib/jvm/java-17-openjdk-amd64
MY_HOME="/home/tecadmin"

You can set multiple environment variables in this file. Each environment variable must be in a separate line.

During the system reboot, the environment variable written in this file will automatically be assigned and accessible system-wide.

3. Using /etc/profile.d/*.sh files

You can also create a shell script under the /etc/profile.d directory. During the user login /etc/profile script is executed. Tha also executed all the shell scripts (files with .sh extension) under /etc/profile.d directory.

Let’s create a shell script /etc/profile.d/custom-env.sh and set the environment variables using export command.

sudo vim /etc/profile.d/custom-env.sh 

Set the environment variables like:

/etc/profile.d/custom-env.sh 
export JAVA_HOME=/usr/lib/jvm/java-17-openjdk-amd64
export JRE_HOME=/usr/lib/jvm/java-17-openjdk-amd64
export MY_ENV="value1"

The next time the user logged in will automatically set the environment variables. You can print the value of the environment variable using the echo command.

echo $MY_ENV 

value1

Conclusion

This tutorial provides you with the details of setting up the environment variables on the Ubuntu system. These environment variables are very helpful to change the run time behaviors of processes.

I hope this tutorial helped you with the basic understanding of creating environment variables on Ubuntu and Debian systems. Please provide your valuable suggestions in the comments and do share this article with the social platform.

The post Setting Up Environment Variables on Ubuntu appeared first on TecAdmin.

This tutorial will help you to install Apache Solr 9.0 on Ubuntu 22.04 Jammy Jellyfish systems.

Step 1 – Install Java

Apache Solr 9 required Java 11 or greater version to run. It is also tested with Java 17. Make sure that your system satisfied all requirements of Apache Solr. If in case, java is not installed on your system run the following command:

sudo apt update && sudo apt install default-jdk 

After installation, check the active Java version:

java -version 

openjdk version "11.0.15" 2022-04-19
OpenJDK Runtime Environment (build 11.0.15+10-Ubuntu-0ubuntu0.22.04.1)
OpenJDK 64-Bit Server VM (build 11.0.15+10-Ubuntu-0ubuntu0.22.04.1, mixed mode, sharing)

Step 2 – Installing Apache Solr on Ubuntu

At the time of writing this tutorial, Apache Solr 9.0 is the latest available version. That can be downloaded with the following command. In case the download failed, visit the Solr download page to get the latest version.

To download Apache Solr 9.0, type:

wget https://dlcdn.apache.org/solr/solr/9.0.0/solr-9.0.0.tgz 

After downloading, extract the Apache Solr service installer shell script from the Solr archive file.

tar xzf solr-9.0.0.tgz solr-9.0.0/bin/install_solr_service.sh --strip-components=2 

Then, start the Solar installation on Ubuntu by executing the following command. Make sure to run the command from the same directory of the downloaded archive file.

sudo bash ./install_solr_service.sh solr-9.0.0.tgz 

This will complete the Apache Solr installation on your Ubuntu system.

Step 3 – Manage Solr Service

Solr is configured as a service on your system. You can simply use the following commands to Start, Stop and check the status of the Solr service.

• Start Solr service:

  sudo systemctl stop solr 
  

• Stop Solr service:

  sudo systemctl start solr 
  

• Check the status of Solr service:

  sudo systemctl status solr 
  

Step 4 – Create A New Solr Collection

After the successful installation of Solr on your system. Create the first collection in Apache Solr using the following command.

sudo su - solr -c "/opt/solr/bin/solr create -c mycol1 -n data_driven_schema_configs" 

Ouput:
Created new core 'mycol1'

Step 5 – Allow Apache Solr Public Access

The default Apache Solr runs on localhost only. To allow the Solr server publically accessible over networks, edit the /etc/default/solr.in.sh configuration file.

sudo vim /etc/default/solr.in.sh 

Search for the SOLR_JETTY_HOST variable. Uncomment it by removing the starting hash (#) symbol. Set the value to “0.0.0.0”.

Save the file and close it. Restart the Solr service to apply changes.

sudo systemctl restart solr 

Check the Apache Solr listening host address.

sudo ss -tupln  | grep 8983 

As per the above screenshot, the Solr is listening on all (“*”) interfaces.

Step 6 – Access Solr Admin Panel

The default Apache Solr runs on port 8983. You can access the Solr port in your web browser using the server IP address or domain name pointed to that server.

Now, select “mycol1” under core selector drop down in the left sidebar

Here you can view statics of created collection in previous steps named “mycol1”. Click on “Core Selector” on the left sidebar and select created collection.

Conclusion

In this tutorial, you have learned about the installation of the Apache Solr service on the Ubuntu 22.04 Linux system.

The post How to Install Apache Solr 9.0 on Ubuntu 22.04 appeared first on TecAdmin.

The Ubuntu 22.04 users can only install .NET Core 6.0. It doesn’t support .NET Core 3.1 or 2.0 since the distro only supports OpenSSL 3.

The developers should install the .NET Core SDK on their system and the staging or production server needs the .NET Core runtime only. This tutorial walks through installing the .NET core on Ubuntu 22.04 LTS Linux system. You can install .NET Core SDK or set up the runtime environment on your system.

Step 1 – Enable Microsoft PPA

First of all, enable the Microsoft Apt repository on our Ubuntu systems. The Microsoft team provides a Debian package to set up the PPA on the Ubuntu system.

Open a terminal on your Ubuntu system and configure Microsoft PPA by running the following commands:

wget https://packages.microsoft.com/config/ubuntu/22.04/packages-microsoft-prod.deb 
sudo dpkg -i packages-microsoft-prod.deb 

Above commands will create a /etc/apt/sources.list.d/microsoft-prod.list file in your system with the required configuration.

Let’s begin the .NET core installation on the Ubuntu system.

Step 2 – Installing .NET Core SDK on Ubuntu

.NET Core SDK is the Software development kit used for developing applications. If you are going to create an application or make changes to an existing application, you will require a .net core SDK package on your system.

To install .NET Core SDK on Ubuntu 22.04 LTS system, execute the following commands:

sudo apt install apt-transport-https 
sudo apt update 
sudo apt install dotnet-sdk-6.0 

Press “y” for any input prompted by the installer.

That’s it. You have successfully installed .Net core SDK on your Ubuntu system.

Step 3 – Installing .NET Core Runtime on Ubuntu

.NET Core Runtime is required for the system, where you only need to run the application. For example, production or staging environments are required to run applications only.

To install .NET Core Runtime only on Ubuntu 22.04 LTS system, type:

sudo apt install apt-transport-https 
sudo apt update 
sudo apt install dotnet-runtime-6.0 

Press “y” for any input prompted by the installer.

That’s it. You have successfully installed the .NET core runtime on your Ubuntu system.

Step 4 – Check .NET Core Version

You can use dotnet command line utility to check the installed version of the .NET Core on your system. To check dotnet version, type:

dotnet --version

Output:

Step 5 – (Optional) Create a Sample Application

Let’s create a sample application with dotnet core on your Ubuntu system. Create a new console application with the command:

dotnet new console -o HelloWorld

This will create a .Net core application on your system. This will create a directory named “helloworld” under the current directory. You can change to this directory and start working on your application.

cd  HelloWorld

Make your changes to the application and execute the below command to run this application.

dotnet run

You will see the following output as a result.

Remove or Uninstall .NET Core on Ubuntu

In case, the .NET Core is not more required on your system. You can uninstall it from the system with the following commands.

sudo apt remove --purge dotnet-sdk-6.0 dotnet-runtime-6.0 

Also, remove unused packages installed as dependencies:

sudo apt auto-remove 

Conclusion

In this tutorial, you have learned to install .NET Core SDK and Runtime on a Ubuntu 22.04 LTS (Jammy Jellyfish) Linux system. Now, you may like to install Visual Studio Code or Sublime Text editor on your Ubuntu desktop systems.

The post How to Install .NET Core (dotnet) on Ubuntu 22.04 appeared first on TecAdmin.

This tutorial will help you to install Apache Solr 9.0 on Fedora 36/35/34/33/32 Linux systems.

Step 1 – Prerequsities

Apache Solr 9.0 required the Java Runtime Environment (JRE) version 11 or higher. If the system doesn’t have JRE installed, use the following command to install OpenJDK 17 on the Fedora system.

sudo dnf install java-17-openjdk 

You can check the installed Java version at the command line using:

java -version

openjdk 17.0.3 2022-04-19
OpenJDK Runtime Environment 21.9 (build 17.0.3+7)
OpenJDK 64-Bit Server VM 21.9 (build 17.0.3+7, mixed mode, sharing)

Step 2 – Install Apache Solr on Fedora

Now download the required Solr version from its official site or mirrors. You may also use the below command to download Apache Solr 9.0 from its official website. After that extract the installer script.

wget https://dlcdn.apache.org/solr/solr/9.0.0/solr-9.0.0.tgz 
tar xzf solr-9.0.0.tgz solr-9.0.0/bin/install_solr_service.sh --strip-components=2 

Then execute the installer script with bash shell followed with downloaded Archive file. The command will be like below:

sudo bash ./install_solr_service.sh solr-9.0.0.tgz 

This will create a user with the name solr in your system and finish the installation process. After that start the service default Solr port 8983.

Step 3 – Managing Apache Solr Service

Use the following commands to Start, Stop and check the status of the Solr service.

• Start Solr service:

  sudo service solr start 
  

• Stop Solr service:

  sudo service solr stop  
  

• Restart Solr service:

  sudo service solr restart  
  

• Check the Solr service status:

  sudo service solr status  
  

  Output
  Found 1 Solr nodes:
  
  Solr process 30891 running on port 8983
  {
    "solr_home":"/var/solr/data",
    "version":"9.0.0 a4eb7aa123dc53f8dac74d80b66a490f2d6b4a26 - janhoy - 2022-05-05 01:00:08",
    "startTime":"2022-05-26T07:52:42.644Z",
    "uptime":"0 days, 0 hours, 0 minutes, 14 seconds",
    "memory":"61.4 MB (%12) of 512 MB"}
  

Step 4 – Create a New Solr Collection

Apache Solr stores values under a collection. A collection is a single logical index that uses a separate solrconfig.xml configuration file with a single index schema.

You can create a new collection using the Apache Solr command-line utility or using Solr APIs. The below command will create a new collection in Solr named mycol1.

sudo su - solr -c "/opt/solr/bin/solr create -c mycol1 -n data_driven_schema_configs" 

Output:
Created new core 'mycol1'

Step 5 – Allow Solr Access on Public Network

The default Apache Solr runs on localhost only. To allow the Solr server publically accessible over networks, edit the /etc/default/solr.in.sh configuration file.

sudo vim /etc/default/solr.in.sh 

Search for the SOLR_JETTY_HOST variable. Uncomment it by removing the starting hash (#) symbol. Set the value to “0.0.0.0”.

sudo service solr restart  

You also need to open the port in the system firewall. The below-mentioned command will open port 8983 in firewalld.

sudo firewall-cmd --permanent  --add-port=8983/tcp 
sudo firewall-cmd --reload 

Step 6 – Access Solr Web Admin Panel

The default Apache Solr runs on port 8983. You can access the Solr port in your web browser and you will get the Solr dashboard.

I already have mapped the domain solr.tecadmin.net with the Fedora server IP address.

  http://solr.tecadmin.net:8983/

Here you can view statics of created collection in previous steps named “mycol1”. Click on “Core Selector” on the left sidebar and select created collection.

Conclusion

This tutorial helped you to install Apache Solr on the Fedora Linux system.

The post How To Install Apache Solr 9.0 on Fedora 36/35 appeared first on TecAdmin.

This tutorial will help you to change the default login screen background on Ubuntu systems.

Install Required Tools

First of all, install a required library on your system.

sudo apt install libglib2.0-dev-bin

Now download the script that will help you with setting up the login screen background wallpaper on Ubuntu systems.

wget -qO - https://github.com/PRATAP-KUMAR/ubuntu-gdm-set-background/archive/main.tar.gz | tar zx --strip-components=1 ubuntu-gdm-set-background-main/ubuntu-gdm-set-background 

To find out the command help run the following command:

./ubuntu-gdm-set-background --help 

Change the Login Screen Background

You can set an image, solid color, and horizontal or vertical gradient color at the Ubuntu login screen running with Genome display manager (GDM).

Use one of the following commands to change the login screen background of your choice:

• Set an image – Use the following command to set an image to the login background.

  sudo ./ubuntu-gdm-set-background --image /home/user/backgrounds/image.jpg 
  

• Set a solid color – You can also set an solid color to Ubuntu login screen. Use the following command with hex color code. You can generate hex code here.

  sudo ./ubuntu-gdm-set-background --color \#aAbBcC 
  

• Set a horizontal gradient color – It also allows you to make gradient color with two colors. To set the horizontal gradent use following command:

  sudo ./ubuntu-gdm-set-background --gradient horizontal \#aAbBcC \#dDeEfF 
  

• Set a vertical gradient color – Vertical gradient of two colors can be set with command:

  sudo ./ubuntu-gdm-set-background --gradient vertical \#aAbBcC \#dDeEfF 
  

• Reset all changes – You can reset all changes to the original by running command:

  sudo ./ubuntu-gdm-set-background --reset 
  

Here are a few screenshots of the login screen after setting up with the above commands.

Conclusion

This tutorial helped you with changing the login screen background with custom colors on Ubuntu systems. You can revert all changes anytime to get the default login screen.

The post Changing the Login Screen Background in Ubuntu 22.04 & 20.04 appeared first on TecAdmin.

While upgrading the Ubuntu OS version, I faced the following issue with the do-release-upgrade command. Even all the current packages were upgraded with apt upgrade.

sudo do-release-upgrade 

We faced a known issue that would not allow us to continue with the upgrade. You will see the following error message:

Checking for a new Ubuntu release
Please install all available updates for your release before upgrading.

Here are 2 solutions available to resolve this issue. It may be one solution not worked in some situations, try another solution.

Solution 1:

The first solution is to disable all third-party repositories in your system. Use the below given commands to disable all repositories:

cd /etc/apt/sources.list.d 
for i in *.list; do mv ${i} ${i}.disabled; done 

Then clean the Apt update state cache data:

apt clean
apt autoclean 

Now, again start the Ubuntu upgrade process.

sudo do-release-upgrade 

In case the above solution doesn’t now, follow the second solution.

Solution 2:

First of all clean all the Ubuntu upgrade state cache with the following commands.

apt clean 
apt autoclean 

Now, execute the following commands one by one.

sudo apt update 
sudo apt upgrade -y 
sudo apt dist-upgrade 

Finally, run the Ubuntu upgrade process again. Hopefully, this will resolve the issue

sudo do-release-upgrade 

If any of the above solutions resolved your issue, kindly share this tutorial. For any issues or other solutions please comment below.

The post (Resolved) Please install all available updates for your release before upgrading appeared first on TecAdmin.