RHEL 7 HowTo - Linux / Unix Q & A from nixCraft

How to enable firewalld logging for denied packets on Linux

last updated March 2, 2020 in CentOS, Fedora Linux, Iptables, Linux, RedHat and Friends, Suse

How do I enable firewalld logging for denied packets on Linux operating systems so that I can view all dropped packets information? How can I view a log of the traffic blocked by FirewallD under a CentOS/RHEL (Red Hat Enterprise Linux)/Suse/OpenSUSE Linux?

Delta RPMs disabled because applydeltarpm not installed

last updated October 21, 2019 in CentOS, Linux, Package Management, RedHat and Friends

I am getting the following warning on both CentOS 7 and RHEL (Red Hat) 7 when I run yum command:
Delta RPMs disabled because /usr/bin/applydeltarpm not installed.
What is delta RPM (DRPM) and how does it differ from RPM? How do I fix this issue on a CentOS or RHEL 7 server/desktop?

Disable SELinux on CentOS 7 / RHEL 7 / Fedora Linux

last updated February 18, 2020 in CentOS, Linux, RedHat and Friends, SELinux

I need to disable SELinux on CentOS 7. How can I disable SELinux from the command line over ssh based session?

How to create VM using the qcow2 image file in KVM

last updated November 17, 2018 in CentOS, Debian / Ubuntu, Linux, Linux KVM, Suse

I have image.qcow2 file. How do I install the qcow2 image provided in the qcow2 format? How do I create Linux KVM VM from provided image (say image.qcow2) file?

CentOS 7 Run Script When Network Interface is Up (Network Manager)

last updated October 15, 2018 in CentOS, Linux, Networking, RedHat and Friends

I want to run a shell script or other program immediately after my network interface goes up on a CentOS 7 / RHEL 7 server. I created /sbin/ifup-local, but it is not working on a CentOS 7 box but works perfectly on CentOS 6. I am using NetworkManager with CentOS 7. How do I run ifup-post or ifup-pre scripts?

How to install KVM on CentOS 7 / RHEL 7 Headless Server

last updated October 13, 2018 in CentOS, Linux KVM, RedHat and Friends, Virtualization

How do I install and configure KVM (Kernel-based Virtual Machine) on a CentOS 7 or RHEL (Red Hat Enterprise Linux) 7 server? How can I setup KMV on a CentOS 7 and use cloud images/cloud-init for installing guest VM?

How to configure Nginx with Let’s Encrypt on CentOS 7

last updated October 2, 2019 in CentOS, Nginx, openssl, RedHat and Friends

How do I secure my Nginx web server with Let’s Encrypt free ssl certificate on my CentOS 7 or RHEL 7 server? How to configure Nginx with Let’s Encrypt on CentOS 7?