Author: admin

Add custom DNS entries to Pi-Hole

Pi-Hole is the black hole for the internet. As of the most recent Pi-hole Version v2.13.2 with Web Interface Version v2.5.2, a local network should have the necessary tools, DNS and DHCP servers, to run successfully. With that said, what if you want custom DNS settings? I tried this approach successfully, so now one IP resolves to several domain names....Read More »

Add Root Certificates to a CentOS Linux Server

Adding a root authority certificate to a server that does not already have the cert may be added to the server manually. Install the ca-certificates package: Enable the dynamic CA configuration feature: Add it as a new file to /etc/pki/ca-trust/source/anchors/: Use command: CentOS 7 CentOS 7.0 and later include a shared store for certificate authorities. Read the manual for additional...Read More »

Fix the CentOS Root Certificate Authority file

For whatever the reason, the /etc/pki/tls/certs/ca-bundle.crt file may get corrupted, in my case, accidentally overwritten.  I could have gone the route of copying the ca-bundle.crt file from another vanilla server, but I wanted a more elegant solution.  There is one, download a new certificate bundle. Download the new certificate bundle.  Since my ca-bundle.crt was overwritten, there was no need to...Read More »
actualauction

How to Combine Multiple Images Quickly

If you have ever started an eBay auction and wanted to add your large picture collection to it, you will quickly realize that you can only add up to 12 pictures.  While it is true pictures can be added to the body of the auction and linked to an alternate sources, that is extra work. As a work-a-round to the...Read More »

Check if user account is locked in Linux

If you ever needed to know if an account is locked in CentOS Linux, there are a few commands to find those answers. Lock a password using passwd. Additional confirmation that the password is locked.  The double !! indicates that the password is locked.  Note that this user does not have a password. Unlock the password.  Note that the password did...Read More »

A quick way to install the ELK stack

By combining the massively popular Elasticsearch, Logstash, and Kibana (what was the ELK Stack is now the Elastic Stack), Elastic has created an end-to-end stack that delivers actionable insights in real time from almost any type of structured and unstructured data source. There are many resources that offer installation procedures from simple to complex configurations.  This is my take on a simple installation...Read More »

Create a large file in Linux for testing

There are many ways to go about this.  A common favorite is the use of the dd command. This simple two letter command requires so many parameters to accomplish the simple goal of generating a file of a specific size. There is another way, and it's easier to remember too. Create a 100MB file using dd will look something like...Read More »

Reduce the number of commands with sed

Suppose there is a situation that a server has multiple files that are nearly identical and you want to remove content from them.  In this example suppose that server has multiple NIC cards.  There is content that needs to be deleted. The situation, you have five NIC cards.  Each ifcfg-ethx config file contains the values for NM_CONTROLLED, HWADDR, GATEWAY, and...Read More »