Set up Amazon CloudFront with WordPress site - Do it now

This article covers how to set up Amazon CloudFront with WordPress site. WordPress performs reasonably well out of the box, but there is room for improvement—the number of WordPress plugins that address performance is evidence of this.  However, the easiest way to improve the user experience is to accelerate one's entire WordPress website by using CloudFront. 

Doing this will not only improve your site's responsiveness, but it may also reduce the overall cost of operating your WordPress infrastructure, as reducing the load on your web servers may help you scale down the required infrastructure. 

In fact, CloudFront can significantly help your site cope with an unexpected load when your site gets popular.


How does CloudFront help?

Many AWS customers have users spread across the globe that they want to reach. However, what once required an immense engineering effort can now be easily built using AWS Regions and Edge locations, which allow you to serve content from the locations closest to those users.

Data transfers on the internet depend largely on global networks of fiber optic cables, allowing very high bandwidth data transfers. 


As the speed of light is proving a difficult challenge to overcome, Amazon CloudFront improves the experience for users accessing your websites in several other ways, including:

1. Anycast DNS ensures your customers are routed to the nearest edge location.

2. Cached content, when available, is delivered to your users from the edge location.

3. When data needs to be fetched from your site CloudFront optimizes network throughput by managing the transfers between Edge Locations and your website.  This traffic runs over the Amazon Global Backbone, where optimized TCP configuration ensures more bytes are in-flight on the network, improving throughput, while TCP connection re-use eliminates much of the latency associated with establishing connections.   In this way, whether content is cached or not, it will be accelerated by delivery over optimized network paths.

4. Finally, negotiating and offloading Transport Layer Security (TLS) at the CloudFront Edge further improves performance, reducing connection setup latency, and further supporting back-end connection re-use.

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Windows update error 0xC190012E - Fix it now

This article covers methods to resolve Windows update error 0xC190012E.

This error generally happens when the user either tries to update their Windows operating system to Windows 10 v 1903 or when upgrading Windows 10 from insider preview for security reasons.


What triggers Windows Update Error 0xC190012E?

If the Windows Update is continuously failing to search for the Updates or are unable to install them due to error 0xc190012e then here is the problem that causing this error.

1. Missing Registry

2. No Internet accesses

3. An issue in Windows update service

4. Corrupt system files

5. Misconfiguration

6. Virus or Malware attack

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Windows update error 0x800f0805 - Fix it now

This article covers methods to resolve windows update error 0x800f0805. 

Windows update error #0x800f0805 indicates that the Windows edition was not detected. Check that the specified image is a valid Windows operating system image. All you need to do is restart your computer and try to activate it again, and it should work.


Causes of #error 0x800f0805 in Windows Update:

1. Bugs in update delivery to your system – This means that there is no fault in your system, instead, the Microsoft servers are experiencing issues.

2. Corrupted Windows files


Methods to fix the #Windows error 0x800f0805:

1. Using Windows Troubleshooter 

This built-in feature can automatically identify and apply fixes to issues on your device.

2. Manually downloading and installing the update

We can use the official Microsoft Update Catalog to download and install system updates manually.

3. Using System File Checker (SFC)

4. Using DISM

We recommend using a DISM scan after using SFC.

5. Resetting Windows Update components

This method will reset the Windows Update.

6. Reset your PC

If none of the above methods worked, you can freshly reinstall your OS without losing any files or settings by using 'Reset this PC' feature.

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Disable database UTF8 connectivity on Nagios - How to do it

This article covers how to configure disable UTF8 connectivity to the MySQL/MariaDB databases. By default Nagios XI uses UTF8 however sometimes this needs to be disabled to allow MySQL / MariaDB to define the connectivity method.

This configuration ensures that characters from different languages can be correctly stored and retrieved in the databases.


The Nagios XI Configuration Directive

The following configuration directive was added in Nagios XI 5.4.13:

$cfg['db_conn_utf8'] = 0;

 To determine if you currently have that directive enabled, establish a terminal session to your Nagios XI server as the root user and execute the following command:

$ grep db_conn_utf8 /usr/local/nagiosxi/html/config.inc.php

 If the grep command produces NO output then the directive does not exist in your configuration and it needs to be added. This can be added with the following command:

$ printf "\n\$cfg['db_conn_utf8'] = 0;\n" >> /usr/local/nagiosxi/html/config.inc.php

 

If the grep command produced output then it can be changed with the following command (sets it to 0):

$sed -i "s/db_conn_utf8'\] =.*/db_conn_utf8'\] = 0;/g" /usr/local/nagiosxi/html/config.inc.php

Defining the directive to 0 will resolve the issue you for garbled or ??? characters.


If you wanted to change it to 1 then use the following command:

$sed -i "s/db_conn_utf8'\] =.*/db_conn_utf8'\] = 1;/g" /usr/local/nagiosxi/html/config.inc.php

 

The change takes effect immediately.

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Windows Update Error 0x80240440 - Fix it now

This article covers how to fix Windows Update Error 0x80240440. 


To fix Windows Update error 0x80240440:

1. Click Start and start typing on your keyboard for "services.msc"

2. In your search results "services.msc" should show up. Open it with a click.

3. A new windows will open containing all Windows services on your system.

Search for "Windows Update"

5. Right-click the "Windows Update" and then click Stop.


Also, you can clean the Windows Update temporary cache folder:

1. Hold your windows-key pressed and hit "R" key simultanous.

2. A small new windows will appear.

3. Type %windir%\SoftwareDistribution\DataStore in this new window and click OK.

4. This will open Windows Explorer on the correct location.

5. Delete all contents of this folder. (Hint: Use Ctrl + A to select all files and folders).


Eventually, you can start the Windows Update Service again:

1. Switch back to the windows Services.

2. Locate Windows Update.

3. Right-click on it and choose Start.

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SELinux users on CentOS 7 – Actions and Deciphering error messages

This article covers more information about SELinux users on CentOS 7.


Deciphering SELinux Error Messages

We looked at one SELinux error message. We were then using the grep command to sift through /var/log/messages file. Fortunately SELinux comes with a few tools to make life a bit easier than that. These tools are not installed by default and require installing a few packages, which you should have installed in the first part of this tutorial.

The first command is ausearch. We can make use of this command if the auditd daemon is running. In the following code snippet we are trying to look at all the error messages related to the httpd daemon. Make sure you are in your root account:

ausearch -m avc -c httpd

In our system a number of entries were listed, but we will concentrate on the last one:

----
time->Thu Aug 21 16:42:17 2014
...
type=AVC msg=audit(1408603337.115:914): avc:  denied  { getattr } for  pid=10204 comm="httpd" path="/www/html/index.html" dev="dm-0" ino=8445484 scontext=system_u:system_r:httpd_t:s0 tcontext=unconfined_u:object_r:default_t:s0 tclass=file

Even experienced system administrators can get confused by messages like this unless they know what they are looking for. To understand it, let’s take apart each of the fields:

type=AVC and avc: AVC stands for Access Vector Cache. SELinux caches access control decisions for resource and processes. This cache is known as the Access Vector Cache (AVC). That's why SELinux access denial messages are also known as “AVC denials”. These two fields of information are saying the entry is coming from an AVC log and it’s an AVC event.


denied { getattr }: The permission that was attempted and the result it got. In this case the get attribute operation was denied.

pid=10204. This is the process id of the process that attempted the access.

comm: The process id by itself doesn’t mean much. The comm attribute shows the process command. In this case it’s httpd. Immediately we know the error is coming from the web server.

path: The location of the resource that was accessed. In this case it’s a file under /www/html/index.html.

dev and ino: The device where the target resource resides and its inode address.

scontext: The security context of the process. We can see the source is running under the httpd_t domain.

tcontext: The security context of the target resource. In this case the file type is default_t.

tclass: The class of the target resource. In this case it’s a file.

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