Linux tutorials for systems administrators and users wanting to manage linux systems, covering various topics such as administration, security, performance tuning, upgrades, and maintenance.
What is LetsEncrypt? Let’s Encrypt is a certificate Authority that launched in 2016 providing free TSL SSL certificates that renew every 90 days. There are several validation methods for LetsEncrypt to verify the domain you are generating the certificate for is one you actually control. In this guide we will be utilizing the webroot method. […]
What is LVM Logical Volume Managment (LVM) is an abstraction layer between physical devices and the file systems which they create. This can make disk management easier by adding abilities to shrink or expand filesystems by just adding additional physical devices no longer being limited to a single physical device as the volume can span […]
By default Kernel-Based Virtual Machines(KVM) are not set up to access a serial console on the host using virsh. To enable a serial virsh console, so you can view text-based output on the host machine from the virtual machine you will need to make modifications to both the virtual machine and the physical machine. Enabling […]
What is SELinux? Security-Enhanced Linux (SELinux) was developed to provide access control for linux. It goes beyond file permissions and ACLs to create a more secure environment by limiting access. It is based on subjects, objects, and actions. A subject is the running command or application(example proftpd), the object is anything that can be accessed […]
What is FirewallD? Firewalld was introduced in CentOS 7/ RHEL 7 with both a GUI and command line interface for making changes. It is a alternative for using IPtables. If offers a zone based firewall configuration that allows you to enable different zones with different levels of trust. Different Zone possibilities Zones change be changed, […]
To recover the root password on a linux system if you do not have it have misplaced it depends on the major release of the OS. This guide will cover both CentOS 6(and prior releases) and CentOS 7. Recover a root password on CentOS 6 or older You will need to boot into single user mode. […]
Iptables is a firewall service included in CentOS, in CentOS 7 its offered as a alternative firewalld is offered as well. Iptables uses netfilter to filter chains. Essentially you create a chain of filter rules to process how incoming and outgoing data is handled. You can view more about iptables on Netfilter Iptables rule format […]