How to monitor a log file on Linux with logwatch

Linux operating system and many applications create special files commonly referred to as “logs” to record their operational events. These system logs or application-specific log files are an essential tool when it comes to understanding and troubleshooting the behavior of the operating system and third-party applications. However, log files are not precisely what you would […]
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How to check hard disk health on Linux using smartmontools

If there is something that you never want to happen on your Linux system, that is having hard drives die on you without any warning. Backups and storage technologies such as RAID can get you back on your feet in no time, but the cost associated with a sudden loss of a hardware device can […]
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How to monitor and troubleshoot a Linux server using sysdig

What is the first thing that comes to mind when you need to track system calls made and received by a process? You’ll probably think of strace, and you are right. What tool would you use to monitor raw network traffic from the command line? If you thought about tcpdump, you made an excellent choice […]
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How to configure a host intrusion detection system on CentOS

One of the first safety measures that any sysadmin may want to implement in their production servers is a mechanism to detect file tampering – not only the content of files, but also their attributes. AIDE (short for “Advanced Intrusion Detection Environment”) is an open source host-based intrusion detection system. AIDE checks the integrity of […]
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How to configure HTTP load balancer with HAProxy on Linux

Increased demand on web based applications and services are putting more and more weight on the shoulders of IT administrators. When faced with unexpected traffic spikes, organic traffic growth, or internal challenges such as hardware failures and urgent maintenance, your web application must remain available, no matter what. Even modern devops and continuous delivery practices […]
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How to set up RAID 10 for high performance and fault tolerant disk I/O on Linux

A RAID 10 (aka RAID 1+0 or stripe of mirrors) array provides high performance and fault-tolerant disk I/O operations by combining features of RAID 0 (where read/write operations are performed in parallel across multiple drives) and RAID 1 (where data is written identically to two or more drives). In this tutorial, I’ll show you how […]
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How to manage configurations in Linux with Puppet and Augeas

Although Puppet is a really unique and useful tool, there are situations where you could use a bit of a different approach. Situations like modification of configuration files which are already present on several of your servers and are unique on each one of them at the same time. Folks from Puppet labs realized this […]
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How to use logrotate to manage log files in Linux

Log files contain useful information about what is going on within the system. They are often inspected during troubleshooting processes or server performance analysis. For a busy server, log files may grow quickly into very large sizes. This becomes a problem as the server will soon run out of space. Besides, working with a single […]
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How to create a software RAID-1 array with mdadm on Linux

Redundant Array of Independent Disks (RAID) is a storage technology that combines multiple hard disks into a single logical unit to provide fault-tolerance and/or improve disk I/O performance. Depending on how data is stored in an array of disks (e.g., with striping, mirroring, parity, or any combination thereof), different RAID levels are defined (e.g., RAID-0, […]
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How to harden Apache web server with mod_security and mod_evasive on CentOS

Web server security is a vast subject, and different people have different preferences and opinions as to what the best tools and techniques are to harden a particular web server. With Apache web server, a great majority of experts -if not all- agree that mod_security and mod_evasive are two very important modules that can protect […]
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