How to solve error message Got permission denied while trying to connect to the Docker daemon socket

This article is an article to solve the error message. The error message is a specific error message appears upon executing a single command. The command is a command to execute a tool with the name of ‘docker’. Below is the output of the command execution :

user@localhost:~$ docker ps -a
Got permission denied while trying to connect to the Docker daemon socket at unix:///var/run/docker.sock: Get http://%2Fvar%2Frun%2Fdocker.sock/v1.39/containers/json?all=1: dial unix /var/run/docker.sock: connect: permission denied

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How to Flush DNS in Ubuntu Linux 18.04


The main purpose for writing this article is to show how to flush DNS in Ubuntu Linux 18.04. This is actually happening almost all the time. It happens when there is a new entry added in this context in the local DNS Server. Sometimes, a client with an installed Ubuntu Linux in it cannot resolve that entry. It is a new entry of a specific IP Address of any resources in the network. Normally, the IP Address has a representative string format address pointing on those resources. The following is an example of it :     app.myapp.web

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How to list file with a regular expression pattern in linux using a command

This is just an additional trick to list files in a folder. The file listing is done in the linux operating system. But the listing process is not trying to list all files. All the file listed must be in a certain pattern. In order to be able to list all of those files, there is a specific command to achieve it. As an additional, the file listing has a specific pattern. Before listing files with the specific pattern, below is the normal command for listing all the files :

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How to install DVWA in Linux Ubuntu 18.04


This article specifically discuss on how to install DVWA in Linux Ubuntu 18.04. Most important thing before start installing is to know what DVWA is. Actually, DVWA stands for Damn Vulnerable Web App. It is a PHP/MySQL web application which particularly have lots of vulnerable along with it. Using DVWA, security professionals can use it to test their skills and tools in a legal environment and also help web developers better understand the processes of securing web applications.

Steps of Installation

How can someone use DVAM in order to use it for testing and securing web applications?. First of all, installing it in the system is important. The installation consists of two sections or two parts. The first one is the preparation part. After that, the latter one is the real installation process.

Preparation for the installation

In this section, it is focusing on the preparation for further installation. Those things which are necessary and important for DVWA to run is listed as follows :

1. Make sure there is a Web Application Server run on the operating system. It can be Apache Webserver or Nginx or any other types of Web Application Server.

2. The next thing which is important is the availability of Database Server. In this context, it is MySQL Database Server.

3. The last one is the support of executing PHP script. The support definitely is available by configuring the Web Application Server so that DVWA can run on it.

The installation of DVWA

After all the preparation is finish, continue on to the main part of the installation. It is obviously the installation of DVWA. Below are steps for placing it into the system :

1. Clone the DVWA into the system using ‘git’ command. Actually, DVWA source exist in the following link. Previously, it exists in this link. Type the ‘git’ command in the command line :

git clone

Using the above command, perform it to clone the DVWA source as follows :

user@hostname:~$ git clone
Cloning into 'DVWA'...
remote: Enumerating objects: 6, done.
remote: Counting objects: 100% (6/6), done.
remote: Compressing objects: 100% (6/6), done.
remote: Total 2986 (delta 0), reused 3 (delta 0), pack-reused 2980
Receiving objects: 100% (2986/2986), 1.52 MiB | 907.00 KiB/s, done.
Resolving deltas: 100% (1308/1308), done.

2. Move the cloned source to the Web Application Server document root directory folder. And then, configure the Web Application Server so that the address of DVWA can be accessed in the browser. The following is the image of the DVWA :

How to install DVWA in Linux Ubuntu 18.04

3. Proceed to configure the Web Application Server. In order to solve the ‘allow_url_include’ as in the image above, just read the article in this link. Basically, just edit php.ini file and set the ‘allow_url_include’ to On. After solving the problem, refresh the page and the following page will appear :

4. According to the image above, there is a problem with the reCAPTCHA key. It is currently missing. So, in order to solve it, read the article in this link. The article shows how to generate reCAPTCHA key.

5. After generating the reCAPTCHA key, just copy and paste it to the DVWA configuration file. The file is ‘config/’ and it exist in the root folder of the DVWA. The following is the configuration line for the reCAPTCHA in the file :

# ReCAPTCHA settings
#   Used for the 'Insecure CAPTCHA' module
#   You'll need to generate your own keys at:
$_DVWA[ 'recaptcha_public_key' ] = '';
$_DVWA[ 'recaptcha_private_key' ]  = '';

Below is an example of the reCAPTCHA page showing the generated key :

Just copy the value in the COPY SITE KEY to the $_DVWA[‘recaptcha_public_key’] and the COPY SECRET KEY to the $_DVWA[‘recaptcha_private_key’] accordingly. Don’t forget to refresh the page. And the installation page of DVWA will change as follows :

6. Since the reCAPTCHA key has already exist, continue on the installation process by clicking the Create/Reset Database button. But don’t forget to create the database first. If there is no problem on the database connection and the installation is a success, the following login page will be presented :

7. Type ‘admin’ in the Username field and ‘password’ in the Password field to login to the DVWA web application. Click the Login button and the following page will appear :

8. Finally, the DVWA web application is active and accessible.