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Author Archives: geoff

Intelligence is the ability to avoid doing work, yet getting the work done. ~Linus Torvalds

Writing your first AWS CloudFormation Template

When starting out in AWS, and trying to understand everything about CloudFormation, I admit, I struggled a little bit. All of the different types of things that you can do in CloudFormation was both amazing and frightening at the same ...

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Installing Docker and running your First Image

The technology world moves so fast, especially now. It also seems that technology comes and then goes, but then comes back even better than it use to be. Take Docker for an example, it’s a container technology that allows developers ...

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How to check if ETags are being served

We all know of the Apache ETag vulnerability, and if you don’t know how to fix it, it’s pretty quite simple — all you need to do is add: ETag None to your apache vhost configuration and restart apache. But ...

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Estimate how long shred or rm will take on millions of files

Today I came across a challenge, try and figure out how long it will take to remove millions of files from our systems. We are all about security, so we need to run shred rather than rm when we remove ...

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RHEL / CentOS: Safely remove old unused Kernels

I have ran into it before when you do a yum update, it prompts you telling you that there isn’t enough space free on the /boot partition. You have two options at this point, either increase the space the /boot ...

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RHEL5 / CentOS5: File Conflicts when Upgrading VMWare Tools with Yum

One of the issues that I have ran into is when you’re running VMWare virtual machines, and a new kernel comes out, it seems to break the vmware-tools upgrade processes. It was extremely frustrating, because you would go to update ...

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RHEL: Cannot retrieve repository metadata (repomd.xml) for repository

I’ve ran into this issue a few times where I currently work, and it was extremely frustrating trying to figure out why I was unable to update our systems via yum, and kept receiving this error. What we found for ...

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Simple Bash Script to Sort File Types into Directories

Often times I find myself needing to sort a lot of files into certain directories, for example I have downloaded a lot of free ebooks and a lot of them have different file types such as epub, mobi, azw, or ...

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Disabling root login on Linux

One of the biggest mistakes any Linux Administrator can make is allowing root to log into the server directly via SSH, the reason this is a huge mistake is root is an account that everyone knows the name of so ...

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How to add a new Linux user account

Adding a new user to a Linux machine is one of the simplest things to do. The useradd command works under any linux distro. You will however need to be root to add the new user via the useradd command, ...

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