Resources, Articles, Tricks, and Solutions in connection to Server Management Service

Enable FirewallD logging for denied packets on Linux

This article will guide you on how to enable #FirewallD logging for denied packets on #Linux. It is an important task to keep an eye on the rejected and dropped packets using FirewallD for #Linux system administrators. 

To enable logging option you need to use #LOG iptables/kernel module. It turn on kernel logging of matching packets. When this option is set for a rule, the Linux kernel will print some information on all matching packets (like most IP header fields) via the kernel log.

To log a dropped packet in iptables:

1. iptables -N LOGGING: Create a new chain called LOGGING.

2. iptables -A INPUT -j LOGGING: All the remaining incoming packets will jump to the LOGGING chain.

3. line#3: Log the incoming packets to syslog (/var/log/messages).

To  restart iptables:

i. To start firewall from a shell enter: # chkconfig iptables on. # service iptables start.

ii. To stop firewall, enter: # service iptables stop.

iii. To restart #firewall, enter: # service iptables restart.

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Node js Application with Docker on Ubuntu

This article will guide you on how to build a Node.js Application with Docker on Ubuntu. npm install downloads a package and it's dependencies. #npm install can be run with or without arguments. When run without arguments, npm install downloads dependencies defined in a package. json file and generates a node_modules folder with the installed modules.

The #docker build command builds Docker images from a Dockerfile and a “context”. 

A build's context is the set of files located in the specified PATH or URL . The build process can refer to any of the files in the context. 

With Dockerfile written, you can build the image using the following command: $ docker build .

Containerizing an #application is the process of making it able to run and deploy under Docker containers and similar technologies that encapsulate an application with its operating system environment (a full system image).

Some Docker #commands:

1. docker run – Runs a command in a new container.

2. docker start – Starts one or more stopped containers.

3. docker stop – Stops one or more running containers.

4. docker build – Builds an image form a Docker file.

5. docker pull – Pulls an image or a repository from a #registry.

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Install WireShark CentOS

This article will guide you on how to install WireShark on #CentOS. WireShark is one of the leading #network analyzing tools. It helps in troubleshooting the traffic problems of a server and malicious activity. 

Wireshark is an open-source, free network packet analyzer, used to capture and analyze network traffic in real-time.

Basically, with Wireshark you can capture and view data traveling through your network.

You can install WireShark with yum install wireshark-gnome . 

After you install it, the Wireshark application will be at /usr/sbin/wireshark .

To install #wireshark on RHEL 8 / CentOS 8 Linux step by step instructions:

1. Install package called Whireshark using the dnf command. For a GUI Wireshark application execute: # dnf install wireshark To install Wireshark command line tool only execute: # dnf install wireshark-cli.

2. Launch Wireshark.

To install Wireshark from #terminal:

Open terminal and type the #commands:

i. sudo apt-get install wireshark.

ii. sudo dpkg-reconfigure wireshark-common.

iii. sudo adduser $USER wireshark.

iv. wireshark.

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Prestashop 404 error on homepage

This article will guide you on how to resolve Prestashop 404 error on homepage which mainly occurs due to many reasons which include bad permissions, memory limit, a problem with .htaccess file, and many more. 

The HTTP error 404, or more commonly called "404 error", means that the page you are trying to open could not be found on the server.

This is a client-side incident which means either the page has been deleted or moved, and the URL has not been modified accordingly, or that you have misspelled the URL.

In other words, this means that there is no web page corresponding to the entered URL.

To resolve a #Prestashop HTTP 404 error:

1. The first thing to do is to refresh the page. Press F5 to refresh the URL.

An error may have occurred if the page wasn't loaded correctly.

2. Clear the browser cache and delete cookies. If you are able to connect to the site via another device such as your mobile phone, clearing the cache and clearing cookies should easily solve the problem.

3. Check the #URL and make sure it is spelled correctly.

Check spelling, hyphens, page extension, etc.

4. Remove malware: some malware can cause a 404 error to occur. It is imperative to make sure that your computer is protected and that it does not contain viruses.

5. Contact the site owner to report the 404 error. If you are the website owner, contact your web host and request further information.

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Drupal Ajax error 500

This article will guide you on steps to resolve drupal #ajax error 500 which occurs due to various reasons like insufficient memory, bad permissions, and broken modules.

An internal server error happens when the server encounters a situation it doesn't know how to handle. 

Any syntax #errors will cause a 500 Internal Server Error message to be displayed instead of your #website. 

To confirm whether a misconfiguration . htaccess is the cause of the 500 Internal Server error, either remove or rename the . htaccess file temporarily and then try to reload the page.

To Resolve 500 Internal Server #Error in #Drupal:

1. Debugging the Issue. The first step is to make sense of the situation and try to make sense of the error.

2. Check if the Admin Works.

3. Revert Recent Changes.

4. Audit Your Plugins/Extensions/Modules.

5. Check File Permissions.

6. Increase PHP Memory Limit.

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Joomla 503 service unavailable

This article will guide you on method to fix #Joomla #503 service unavailable which occurs due to web traffic or bad PHP scripts or corrupted #modules.

A 503 Service Unavailable Error is an HTTP response status code indicating that a server is temporarily unable to handle the request. This may be due to the server being overloaded or down for maintenance. 

To Fix an #HTTP #Error 503:

1. Reboot your server.

2. Check to see if your web server is going through maintenance.

3. Fix faulty firewall configurations.

4. Sift through your server-side logs.

5. Comb through your website's code to find bugs.

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