Author Archives: Darren

How to set up a billing alarm on AWS

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The video will show you how to set up a billing alert on AWS. We will do this by setting the alarm in AWS CloudWatch. To begin you will need to:

  1. log into your AWS account.
  2. Next you will need to navigate to the N Virginia region.
  3. Once in the region you can open Cloud watch t
  4. Then Click on billing
  5. Click create alarm
  6. Select metric
  7. Select USD
  8. Enter the value you want, in our case 100 USD
  9. Click create a new topic and enter you email
  10. Be sure to verify your email
  11. Click next
  12. Give your alarm a name and click next
  13. Click create alarm.

A full video tutorial can be seen here:

 

How to install Virtual box Guest additions on CentOs 8, ake CentOS 8 full screen in Virtual box

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This virtualbox tutorial will show you how to install Virtual box Guest additions on CentOs 8.

When this process is done you will be able to make CentOS 8 full screen in Virtual box, so in affect the video shows how to make Centos 8 full screen in Virtual box.

The command that i run to download the relevant packages are:

sudo yum install tar bzip2 kernel-headers perl gcc make elfutils-libelf-devel

How to use snapshots on Virtualbox

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This Virtualbox tutorial will show you how to take a snapshot on Virtualbox. First you will see how to take a snapshot of a running virtual machine. You will then see how to restore the snapshot. Snapshots allow you to save the state of a virtual machine; this can be useful when you want to test something, or you’re about to make a change to that virtual machine, and you need to be able to roll back to a working instance. Snapshots have saved me on numerous occasions and are an excellent feature!

How to Generate a CSR on CentOS 8

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This video will show you how to generate a Certificate Signing Request CSR on CentOS 8.

A CSR is normally sent to a certificate provider who will supply you with a certificate based from the CSR.

This video uses CentOS 8 Linux however the process should be much the same on all Linux operating systems.

The commands in this video are:

  • sudo yum install openssl
  • openssl req -new -newkey rsa:2048 -nodes -keyout yourkeyname.key yourdomainname.csr

Unable to open primary script

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This Video will show you how to solve the error: unable to open primary script permission denied on Centos 8.

In this video i was trying to install moodle and when i went to access the site, I kept getting an error. In the Apache logs i could see the error: unable to open primary script: ‘Unable to open primary script varwwwhtmlmoodleindex.php (Permission denied)

When i delved into the error i could see that it was selinux was causing the issue.

You can disable selinux on the fly by entering: sudo setenforce 0

but to permanently disable you should edit the/etc/selinux/config file and

set selinux to disabled SELINUX=disabled

 

How to ensure a service or program starts on boot on Centos Linux

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This Video will show you how to ensure that a service or program starts on boot on Linux. This video was recorded on CentOS 8 but the method shoudl work on most Linux Distros including Ubuntu.

The command that you need to run is:

sudo chkconfig servicename on

This command will ensure that the service starts on boot on Linux

Java keystore tutorial: How to export a Certificate from a Java Keystore

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This Java Keytool Tutorial will show you how to export a Certificate from a Java Keystore.

To begin you will first run (Note ensure that you update the relvnet commands to reflect your Keystore, alias and certificate names) :

keytool -list -keystore keystore.jks

to see what certificates reside in the java keystore.

Next you will run:

keytool -exportcert -alias domain -file domain.der -keystore keystore.jks

to export the Certificate.