January 2023 – Friki Linux

Monitoring Oracle Servers With Checkmk

Posted on 2023-01-31 by Kernel

Databases are essential for many IT processes. Their performance and reliability depends on many factors and it makes sense to use a dedicated tool that helps you to stay on top of things. Monitoring your database with an external tool helps you identify performance issues proactively, but there are many factors to consider. With the wrong approach, you run the risk of missing valuable information and also can waste a lot of time configuring your database monitoring.

In this tutorial, I will give a quick guide on how to monitor Oracle Database with Checkmk, a universal monitoring tool for all kinds of IT assets. Oracle Database is one of the most common database management systems (DBMS) for relational databases and Checkmk comes with a great preconfigured Oracle monitoring, so it will only take you a few minutes to get started. This will not only ensure the best performance of your databases, but also give you the option to find optimization opportunities.

Preconditions

You need a Checkmk site up and running. For this article, I am using the Checkmk Free Edition version 2.1.0p19, which I installed on Ubuntu server (version 20.04). Checkmk runs on Linux, including RHEL, CentOS, Debian, and others, as well as in a container, or as a virtual appliance. You can download the latest Checkmk version for all platforms from the official Checkmk website and follow this video tutorial to take your first steps.

In this tutorial, I will use a simple Oracle server as an example. In my case, my Oracle database version 19.0 runs on a hardware server, and I use Rocky Linux version 9.0 as my operating system. I will show you how to configure and install the Checkmk agent. However, Checkmk can also monitor remote databases without the need to install an agent.

You don’t need any previous experience with Oracle monitoring, as Checkmk takes over the collection of the most important monitoring services and also sets threshold values for warnings and critical states. However, you need access rights to create user accounts for the database you want to monitor, you will do this in the first step.

Step 1: Creating an Oracle user account for the monitoring

First, you need to create a user account that Checkmk will use to query the monitoring data from your database. In my case, I am using SQL Plus and create the user through the terminal. The procedure differs depending on which Oracle environment and tool you are using. You can read more details about this in the Oracle documentation.

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Find WiFi Password Of Connected Networks In Linux

Posted on 2023-01-31 by Kernel

Find WiFi Password Of Connected Networks In Linux

If you are using Linux and looking for methods to find WiFi passwords of connected networks in Linux-based operating systems then this blog is for you. There are multiple ways to find the WiFi password of connected networks in Linux.

How To Find WiFi Password Of Connected Networks In Linux

Method 1:

View Saved WiFi Password Of Connected Networks From Command line In Linux

In Ubuntu and derivatives, the wireless network configuration files are saved in the /etc/NetworkManager/system-connections/ directory.

ls /etc/NetworkManager/system-connections/

You will see an output with the password

Method 2:

How To Show Saved WiFi Password using Nmcli

Run the following command to find the list of available wireless network connections:

nmcli device wifi list

Now, Display the password of the currently connected WiFi network using the following command:

nmcli device wifi show-password

Find All Symbolic Links in Linux

Posted on 2023-01-31 by Kernel

How do you find a soft link?

You can use the ls command. Some distributions show the links in a different color. The long listing is always reliable because it shows links with l.

lrwxrwxrwx 1 abhishek abhishek 14 Jan 31 18:07 my_link -> redirects.yaml

You can also use the tree command:

This is okay if you have a couple of links in the current directory. But what if you want to see the links in a nested directory structure or the entire system?

In this tutorial, I will be showing you two ways to accomplish this mission:

Using the find command
Using the symlinks utility

So let’s start with the first one.

Use find command to look for symbolic links

To find the symbolic links using the find command, you can use the following command syntax:

find Target_directory -type l

For example, here, I searched for available symbolic links inside the Links directory:

find Links/ -type l

But by default, the find command will initiate the recursive search and if you want to limit the search to a certain depth, you will have to use the -maxdepth flag.

So let’s say I want to restrict the search to level 1 for the Links directory, I will be using the following:

find Links/ -maxdepth 1 -type l

And if you want detailed output including the file permissions, user groups, etc. then you will have to pair the find command with -ls flag:

find Target_directory -type l -ls

If you want a system-wide search, you can use / in the command.

Use the symlinks utility to find all symbolic links

This tool is what I used while pursuing my internship in networking.

But it does not come pre-installed though. You can install it using your distribution’s package manager. For Ubuntu/Debian, use:

sudo apt install symlinks

Once you are done with the installation, use the given command structure to look for available symbolic links:

symlinks -v target_directory

Here, the -v option gives verbose output.

But by default, the symlinks utility won’t look into subdirectories. Enable recursive search with the -r option:

symlinks -vr target_directory

The output has specific terms. Let me explain them.

relative indicates that links are relative to the current working directory in which the link resides.
other_fs means the link is indicating a different filesystem. In my case, it is indicated to the external drive.

Symbolic Links are Easy!

Really, they might sound like a huge deal but we made sure to break the topic bit by bit.

Such as if you are a complete beginner, you can refer to the beginner’s guide to symbolic links:

And if you want to follow them to their origin, you can refer the following guide:

I hope you will find this guide helpful. And if you have any queries or suggestions, be my guest in the comments section.

How To Install Git On Ubuntu 22.04 LTS [2023]

Posted on 2023-01-30 by Kernel

How To Install Git On Ubuntu 22.04 LTS

In this tutorial post, we will show you the ways to install Git on Ubuntu 22.04 LTS. Git is a free and open-source distributed version control system.

How To Install Git On Ubuntu 22.04 LTS [2023]

Before starting the installation of Git on Ubuntu, we need to make sure that all packages installed on Ubuntu 22.04 are up to date. Run the following command to see whether the packages are up to date or not.

 apt update -y

In most cases, Ubuntu 22.04 LTS should have the git package installed by default. Run the following command to check if you have git installed or not. If you already have git installed on your system, this command will display the version of git you currently have installed on your system.

 git --version

Output
git version 2.34.1

If the git package is not installed, run the following commands in your Ubuntu 22.04 LTS:

apt update

apt install git

Enter ‘Y’ to continue the installation.

To verify whether the installation was successful or not, you can run the git –version command again.

Meanwhile, if you want to install a different version of Git then run the following command to check which git version is available to install.

 apt-cache policy git

How To Install git from Source On Ubuntu 22.04 LTS

If you want to Install the latest or different version of git then you can do it by installing git from the source. Run the following commands one by one to update the packages and install all the dependencies needed.

 apt update

 apt install libz-dev libssl-dev libcurl4-gnutls-dev libexpat1-dev gettext cmake gcc

If you are confused about the version, you can visit the website https://mirrors.edge.kernel.org/pub/software/scm/git/ and you can choose which git version you want to install. Now, after finalizing the version, run the following command to download Git.

 wget https://mirrors.edge.kernel.org/pub/software/scm/git/git-2.9.5.tar.gz

Now unpack the compressed tarball file:

 tar -xzf git-2.9.5.tar.gz

Next move to the git directory:

 cd git-2.9.5

Now, it’s time to install git on Ubuntu.

 make prefix=/usr/local all

 make prefix=/usr/local install

 exec bash

Run the following command to check if the installation was completed or not

 git --version

This Indicator Shows CPU, GPU, Memory Usage on Ubuntu 22.04 Panel

Posted on 2023-01-30 by Kernel

There are several Gnome Shell extensions to display system resource usage in Ubuntu, but in this tutorial I’m going to introduce an indicator that works in not only GNOME, but also Unity, MATE, and Budgie desktop environments.

It’s Indicator-SysMonitor, a free and open-source applet developed by the leader of Ubuntu Budgie team.

With it, user can display the usage and/or temperature of the following system resource in top-panel:

average CPU usage.
NVIDIA GPU utilization.
Memory usage.
network upload/download speed.
CPU, NVIDIA GPU temperature.
Swap usage.
Public IP address.

Most important is that user can customize the output, by setting which one or ones to display, in which order with which text. User just need to click the indicator on panel to open ‘Preferences’ dialog from pop-down menu, and format the output code in ‘Advanced’ tab.

How to Install Indicator-Sysmonitor

The developer has an Ubuntu PPA contains the packages for Ubuntu 18.04, Ubuntu 20.04, Ubuntu 22.04, Ubuntu 22.10, and even the next Ubuntu 23.04.

1. First, press Ctrl+Alt+T on keyboard to open a terminal window. When it opens, run command to add the PPA:

sudo add-apt-repository ppa:fossfreedom/indicator-sysmonitor

Type user password when it asks and hit Enter to continue.

2. For the old Ubuntu 18.04, you need to manually refresh package index after adding PPA:

sudo apt update

3. And, install the indicator applet via command:

sudo apt install indicator-sysmonitor

Finally, search for and open the applet like a normal application (it has same icon to System Monitor).

And click on the applet to open Preferences, and turn on start at login, configure output layout, refresh interval, etc.

Uninstall Indicator-Sysmonitor

You can close the applet by clicking on it in panel and select “Quit”. And remove the package at any time by running a single command in terminal window:

sudo apt remove indicator-sysmonitor

Also remove the PPA repository, either by running the command below or open “Software & Updates”and remove source line under “Other Software” tab.

sudo add-apt-repository --remove ppa:fossfreedom/indicator-sysmonitor

JD Sports admits data breach

Posted on 2023-01-30 by Kernel

JD Sports has warned customers that bought items on its website, as well as those of Size?, Blacks and Millets, between November 2018 and October 2020 may have been impacted in the breach.

The company has urged customers to be wary of potential phishing emails, calls and texts in the aftermath of the breach, while claiming they were proactively contacting those whose details were confirmed to be stolen. Paul Bischoff, Consumer Privacy Advocate at Comparitech echoed this sentiment, warning that “customers of JD and its affiliated brands should be on the lookout for targeted phishing messages from JD or a related company. These emails will attempt to get victims to click on a link or malicious attachment. The links might go imitation login pages where victims are tricked into handing over their passwords or payment info. Never click on links or attachments in unsolicited messages!”

While it is not believed that passwords or full payment card data was exposed, JD Sports has admitted that cybercriminals may have gained access to the final four digits’ of customers’ payment cards.

Neil Greenhalgh, CFO at JD Sports, apologised to affected customers and confirmed that the company is working to mitigate damages.

“We are continuing with a full review of our cyber security in partnership with external specialists following this incident. Protecting the data of our customers is an absolute priority for JD,” he said.

A spokesperson for the Information Commissioner’s Office later confirmed it was working with the retailer to get to the bottom of the breach.

“We have been made aware of a cyber incident involving the retailer JD Sports and we are assessing the information provided,” they said.

The breach comes amidst a spate of high-profile cyberattacks in recent weeks, including on the UK newspaper The Guardian and email marketing service Mailchimp. Jamie Akhtar, CEO and co-founder of CyberSmart, notes that “JD Sports is the latest British household name to fall prey to a cyber attack. And this really fits the trend we’re seeing; the current economic downturn has led to cybercriminals redoubling their efforts to steal potentially valuable personal data.”

Aside from economic downturn, some experts have cited a fluctuating technology landscape as key factor in these high-profile cyberattacks.

“The JD Sports cyber incident is a reminder for all organisations that globally we can expect an increase in breaches due to our digital dependence, especially as businesses recover from the COVID technology shifts, and continuing threat shifts. Sadly, whilst companies spent years solidifying their capabilities for GDPR, in the last couple of years data has become far more fragmented by quick shifts to the cloud,” said Greg Day, SVP and Global CISO at Cybereason.

Erfan Shadabi, Cybersecurity Expert at comforte AG, argued that cyberattacks on large retail and e-commerce businesses should come as no surprise, considering the enormous amount of sensitive personal data (PII) about existing and prospective customers, as well as their dependence on transactions to drive their business forward.

“Retailers and e-commerce organizations must absolutely assume that their environment is currently under attack and protect this sensitive data accordingly. Businesses in these sectors need to apply data-centric protection to any sensitive data within their ecosystem (PII, financial, and transactional) as soon as it enters the environment and keep it protected even as employees work with that data. By tokenizing any PII or transactional data, they can strongly protect that information while preserving the original data format, making it easier for business applications to support tokenized data within their workflows,” he said.

The post JD Sports admits data breach appeared first on IT Security Guru.

Acronis seals cyber protection partnership with Fulham FC

Posted on 2023-01-30 by Kernel

Acronis, a global and visionary cyber protection company, today announced a three-year partnership with London´s oldest professional football club, Fulham FC. EveryCloud.co.uk will support Acronis as its ‘Strategic #Cyberfit’ delivery partner providing its cutting-edge cyber protection solutions and cloud backup service to the club.

Under the Strategic #Cyberfit delivery partner EveryCloud.co.uk, Acronis will provide Premier League side Fulham FC with a full suite of cyber protection solutions.

Arturs Banks, Head of IT of Fulham FC, said “We are very pleased to be working with Acronis and EveryCloud UK, and we look forward to incorporating them into our cloud backup and file security infrastructure. Their support and expertise will be invaluable to Fulham FC and the Fulham FC Foundation as we continue to prioritise data and cyber security at the club.”

Ronan McCurtin, VP of Sales Europe, Israel and Turkey, Acronis, said “We are proud to be partnering with Fulham FC, a club that understands the importance of keeping their data protected. With EveryCloud.co.uk we have the right partner who will support us in providing the team with a full suite of Acronis cyber protection solutions to protect the team’s data assets and optimise data workflow, facilitating the team performing at its best both on and off the pitch.”

Paul Richards, Director of Technology, EveryCloud.co.uk, added “EveryCloud.co.uk is delighted to partner with Fulham FC alongside our partner Acronis to deliver a complete suite of Cyber Protection services. Our proven track record of working with Acronis will enable Fulham FC to further protect their data, systems and infrastructure with the reliability and performance of Acronis’ products and services. Even the strongest defence needs backup.”

The post Acronis seals cyber protection partnership with Fulham FC appeared first on IT Security Guru.

Netstat Command Examples in Linux

Posted on 2023-01-30 by Kernel

The netstat is one of the most popular utilities to monitor connections over your network.

It allows you to easily monitor incoming and outgoing connections, listening ports, statistics, and more.

In this tutorial, I will show you some of the most examples of the netstat command on Linux.

1. Find all the listening ports

To find all the ports (TCP and UDP), you will have to append the -l flag with the netstat command:

netstat -l

2. List listening and non-listening ports

If you want to get a list of available sockets on your system, you can use the -a flag with the netstat command:

netstat -a

Now, let’s get to more specific ones.

3. Find TCP listening ports

If you want to list ports using TCP protocol and in the listening state, you will have to use -l flag for listening and -t flag for TCP connections:

netstat -lt

4. Find UDP listening ports

To list every listening UDP port on your system, you will have to append -l and -u flag with the netstat command:

netstat -lu

5. List all TCP port connections

If you want to list every socket using a TCP connection including listening and non-listening, use the -at flag with the netstat command:

netstat -at

Want to know the difference between listening and an established state?

LISTENING means it is listening for incoming connections.
ESTABLISHED indicates that the socket has an established connection.

6. List all UDP connections

If you want to list every socket utilizing the UDP, you can use the combination of -a and -u flag:

netstat -au

7. Get a statistical summary of each protocol

This is one of the handiest features of netstat which allows you to find the number of connections established, the number of messages sent and received, and a lot more.

To get a summary of each protocol, all you need to do is append the -s flag:

netstat -s

But what if you want statistics on specific protocols? Here’s how you do it.

8. Get statistics for a specific connection

Let’s start with the TCP.

To get the statistics of TCP connections, all you need to do is use the -s and -t flag with the netstat command:

netstat -st

Similarly, if you want the same for UDP, you will have to use the -su flag:

netstat -su

9. Get raw network statistics

If you are looking for raw data rather than filtered one, it can easily be produced using the -s (for statistics) and --raw (for raw):

netstat -s --raw

10. Find services with PID

If you are into troubleshooting, getting the PID of the service can be very handy. To get PID, all you need to do is use the -p flag:

sudo netstat -p

11. Find a specific listening service on the network

To find a specific listening, you can use the grep command which makes a killer combination while troubleshooting.

So let’s suppose, I want to look for an HTTPS service on listening state which can be done through the following command:

sudo netstat -apl | grep -w https

Want to know how to get more out of grep? you can refer to our detailed guide on that topic:

12. Show transactions of network interfaces

The netstat utility can also be used to list available network interfaces and to get transactions of each one.

For that, all you need to do is append the -i flag to the netstat:

netstat -i

13. Monitor the network continuously using the netstat command

If you want to monitor the network continuously, you can do it with -c the option:

netstat -c

You can use appropriate flags such as -lt with -c and it will look for listening TCP connections continuously:

netstat -ltc

Pretty handy. Right?

More on Networking in Linux

If you have just started your carries or studies on networking, we have a detailed guide on most basic networking commands:

Want to know more about ports? We got you covered on that too:

That was it from my side. And if you have any doubts or have tips for beginners, you can share your precious knowledge through the comments.

6 Tips For Retail Store Owners On How To Increase Profits

Posted on 2023-01-30 by Kernel

6 Tips For Retail Store Owners On How To Increase Profits

Are you a retail store owner who wants to increase profits? If so, then you’ll want to read this blog post. It’ll be sharing six tips that can help you boost your bottom line. So, check out these tips if you wish to improve your sales or cut costs.

Price your goods correctly.

One of the most significant factors affecting your bottom line is the prices you set for your goods. You want to make sure that you are pricing your items correctly so that you can maximize profits. If your fees are too low, customers may be less likely to purchase from you as they may not see the value in what they’re buying. Conversely, if the prices are too high, it may scare away potential customers. To price your goods correctly, you’ll need to understand your target market and what they want. You can also use appropriate pricing software for the retail sector to help you. This software will help you to determine optimal pricing for your products based on the current market conditions.

Offer discounts and coupons

One of the best tips retail store owners can use to increase their profits is to offer discounts and coupons. This customer incentive provides an excellent opportunity for customers to purchase more than they usually would, resulting in more significant profit margins. Discounts and coupons can boost word-of-mouth advertising, as people tend to talk about a good bargain. Deals and coupons should also be promoted across multiple channels for maximum effect — don’t just limit yourself to print ads or your store website. Crafting creative campaigns such as an online contest or giveaway can attract customers from more prominent sources, helping you cross-sell different products and even charge a small fee for entry — that’s extra profits in your pocket.

Train your employees on how to upsell and cross-sell products

As a retail store owner, you know how important it is to increase profits. Training your employees to upsell and cross-sell products is the best way to do this. Upselling is when an employee encourages customers to purchase more expensive items with higher margin rates or additional items while cross-selling is when they market related articles and accessories. This can significantly raise your store’s revenues and ensure customers have everything they need for the products they buy. To train your staff, clearly explain upselling and cross-selling strategies, show them product features, demonstrate potential add-ons, provide examples of successful sales pitches, track purchases resulting from staff recommendations, and give timely feedback. Offering this training will give your employees the skills to maximize revenue for your store business.

Display items in a way that is appealing and easy to find

Retail store owners can increase profits by taking a creative approach to displaying their merchandise. If customers can easily find and view items, they’re more likely to be enticed to make a purchase. Creating appealing displays is critical. Make sure the colors, layout, and organization are visually pleasing. Utilize overhead lighting and soft spotlights on certain items to draw attention. Keeping items neatly displayed in groups will make them more accessible for customers to locate while encouraging impulse purchases. Make the most of limited space by raising shelves and taking advantage of wall displays. A refreshing display after regular intervals helps increase customer satisfaction and brings people back for more shopping experiences.

Keep your store clean and organized at all times.

An organized space helps customers find items quickly and efficiently and can even help to improve their shopping experience. Not only does tidying up your store make a great impression on customers, but it also increases the likelihood that they will buy more by making them feel comfortable in their surroundings. Additionally, ensuring that merchandise is properly stocked and easy to access prevents shoppers from leaving empty-handed if they can’t find what they’re looking for. Taking the initiative to thoroughly clean and organize your store can be a great way to maximize profits.

Always stock up on the items your customers need

An abundant inventory of items your customers demand will ensure they return as repeat customers and help increase sales and profits. An organized inventory schedule can help determine what products are selling well within your store. It also helps predict anything running low and allows you to restock the shelves with the most popular items quickly. Understanding customer needs and having a firm grasp of stock levels will allow store owners to confidently anticipate their customer’s needs to maximize sales and reap the rewards of well-managed profits.

Following these simple tips can encourage your customers to buy more and keep them returning for more. Train your employees to upsell and cross-sell products, offer discounts and coupons, and ensure your store is always clean and organized. Are you doing all of these things in your store? If not, now is the time to start!

How To Change Java Version In Linux [2023]

Posted on 2023-01-29 by Kernel

Tutorial to change Java version In Linux

There may have different Java versions installed on your Linux and sometime you might need to switch between different versions to work on several tasks or projects. In this tutorial, we will show you the best way to change or switch the Java version in Linux.

How To Change Java Version In Linux [2023]

Let’s check the current Java version in your Linux. Run the following command to see the current version of Java on Linux.

 java -version

Run the following command to view the system’s installed Java JDKs and JREs:

sudo update-alternatives --config java

Above command displays all the available Java versions in your Linux.

Meanwhile, you can check the available Java versions using the update-alternatives command too:

sudo update-alternatives --display java

With the above command, you can see the list of all the available JDKs and JRE. Now you need to enter the number in the confirmation prompt on the terminal to select the specific version. Once you enter the selection, you get a message which confirms that the selection is updated.

Bonus Tutorial:

How To Install Java On Ubuntu 22.04 LTS

Run the following commands to install OpenJDK 11 package on Ubuntu 22.04 LTS.

sudo apt update
sudo apt install openjdk-11-jdk

Once the installation is complete, you can verify it by checking the Java version:

java -version

openjdk version "11.0.7" 2020-04-14
OpenJDK Runtime Environment (build 11.0.7+10-post-Ubuntu-3ubuntu1)
OpenJDK 64-Bit Server VM (build 11.0.7+10-post-Ubuntu-3ubuntu1, mixed mode, sharing)

OpenJDK 11 has been installed.

Now run the following command to install OpenJDK 8 Ubuntu 22.04 LTS.

Install Java 8 on Ubuntu On Ubuntu 22.04 LTS.

Run the below command to install OpenJDK 8 package on Ubuntu 22.04 LTS.

sudo apt update
sudo apt install openjdk-8-jdk

Install Oracle Java 14 On Ubuntu 22.04 LTS.

Run the following command to download the Debian file using the command line.

wget --no-cookies --no-check-certificate --header "Cookie: gpw_e24=http%3A%2F%2Fwww.oracle.com%2F; oraclelicense=accept-securebackup-cookie" "https://download.oracle.com/otn-pub/java/jdk/14.0.1+7/664493ef4a6946b186ff29eb326336a2/jdk-14.0.1_linux-x64_bin.deb"

Or download the .deb package from the official download page. Once you download the Debian file, install it on your system using the command below:

sudo dpkg -i jdk-14.0.1_linux-x64_bin.deb