How to find if Log4J is installed in my server

A critical vulnerability (CVE-2021-44228) was identified on the popular log4j logger library used by a lot of popular Java applications.

How to Install MySQL 5.7 on Oracle Linux 7

Oracle Linux 7 comes with MySQL yum repository pre-installed. By Default MySQL 8 repository is enabled. You can disable MySQL

SSL Certficate

acme.sh SSL using manual DNS method

To provision SSL certificate using acme.sh with manual DNS verification method, run When you run this command, you will get

Enable Remote Connection in MS SQL Server

MS SQL Server does not allow remote connection by default. To enable MS SQL remote connection, you need to open

sudo: command not found

On a Debian server, when running a command with sudo, I got the error To fix this, you need to

Static IP for CentOS LXC container

LXC containers get dynamic IP from DHCP. When you stop and start a container, its IP gets changed. If you

Convert image to WebP format in Ubuntu

WebP is an image format for web by Google. The size of webp images are much smaller compared with other

Enable HTTP_X_FORWARDED_FOR in Haproxy

By default, Haproxy won’t forward visitor IP address to backend servers. To enable Haproxy forward visitor IP address to backend

bash: /usr/bin/man: No such file or directory

On Ubuntu, I get the following error This is fixed by installing man with apt-get

How to Migrate CentOS to Oracle Linux

Oracle Linux is Free 100% binary-compatible with Red Hat Enterprise Linux, same as CentOS. Unlike RHEL, Oracle Linux is free

How to delete an mdadm RAID Array

Deleting a software RAID array will result in all data stored in the devices being lost. So be careful when

RAID getting created as /dev/md127

When I create software RAID with mdadm, it gets created as /dev/md127, instead of /dev/md0 I specified while creating RAID.