How to Stop and Disable Firewall on CentOS 8

Most of the time this task is done by system admins but if you work in a small organization like me(God helps you) :) then you need to do many system admin tasks by yourself.

I am writing this blog because recently faced issue similar issue when we moved one of the 19C databases to Azure cloud. After setting up the database application team was not able to reach the database. I did some checking and found that the Linux admin missed disabling the firewall on the DB server. So I decided to stop the firewall on DB server by myself.  

Sharing steps with you all, so may help you on "How to Stop and to Disable Firewall on CentOS 8"

There may be many methods but I used firewall-cmd to stop the firewall.

Man Page DESCRIPTION for firewall-cmd

NAME

       firewall-cmd - firewalld command line client

SYNOPSIS

       firewall-cmd [OPTIONS...]

DESCRIPTION

       firewall-cmd is the command-line client of the firewall daemon. It provides an interface to manage the runtime and permanent configurations.

       The runtime configuration in firewalld is separated from the permanent configuration. This means that things can

       get changed in the runtime or permanent configuration

Note: You need the root user or any user to have SUDO to do this change.

Steps to top and Disable Firewall on CentOS 8:- 

1. Check the Status of the firewall using Firewalld

[root@TEST-D01 ~]# firewall-cmd --state

                                     running

   

2.  Stop firewall using Firewalld

[root@TEST-D01 ~]# systemctl stop firewalld

3. Check the Status of firewall using Firewalld

[root@TEST-D01 ~]# firewall-cmd --state

not running

Keep Sharing :)

How to Change the Timezone in Linux

How to Change the Timezone in Linux

Easy steps to change timezone on "CentOS Stream release 8"

It's very simple to change the timezone of Linux machines. Sometimes as DBA you need to change the timezone on cloud environments when you handling multiple sites on the cloud.

Just follow the below steps to "Change the Timezone in Linux" :-

1) login with root or any sudo user to your machine and check current timezone. 

   [root@TEST-D01 ~]# timedatectl

                                       Local time: Tue 2021-07-13 03:40:06 EEST

                                       Universal time: Tue 2021-07-13 00:40:06 UTC

                                         RTC time: Tue 2021-07-13 00:40:06

                                        Time zone: Europe/Kiev (EEST, +0300)

                                     System clock synchronized: no

                                      NTP service: n/a

                              RTC in local TZ: no

My Current timezone is "Europe/Kiev (EEST, +0300)". 

So Let's change the timezone to Asia. 

2) You can get the list of all timezones in Asia by "timedatectl list-timezones |grep Asia" 

                    [root@TEST-D01 ~]# timedatectl list-timezones |grep Asia

                        Asia/Aden

                        Asia/Almaty

                        Asia/Amman

                        Asia/Anadyr

                        Asia/Aqtau

                        Asia/Aqtobe

                        Asia/Ashgabat

                        Asia/Atyrau

                        Asia/Baghdad

                        Asia/Bahrain

                        Asia/Baku

                        Asia/Bangkok

                        Asia/Barnaul

                        Asia/Beirut

                        Asia/Bishkek

                        Asia/Brunei

                        Asia/Chita

                        Asia/Choibalsan

                        Asia/Colombo

                        Asia/Damascus

                        Asia/Dhaka

                        Asia/Dili

                        Asia/Dubai

                        Asia/Dushanbe

                        Asia/Famagusta

                        Asia/Gaza

                        Asia/Hebron

                        Asia/Ho_Chi_Minh

                        Asia/Hong_Kong

                        Asia/Hovd

                        Asia/Irkutsk

                        Asia/Jakarta

                        Asia/Jayapura

                        Asia/Jerusalem

                        Asia/Kabul

                        Asia/Kamchatka

                        Asia/Karachi

                        Asia/Kathmandu

                        Asia/Khandyga

                        Asia/Kolkata

                        Asia/Krasnoyarsk

                        Asia/Kuala_Lumpur

                        Asia/Kuching

                        Asia/Kuwait

                        Asia/Macau

                        Asia/Magadan

                        Asia/Makassar

                        Asia/Manila

                        Asia/Muscat

                        Asia/Nicosia

                        Asia/Novokuznetsk

                        Asia/Novosibirsk

                        Asia/Omsk

                        Asia/Oral

                        Asia/Phnom_Penh

                        Asia/Pontianak

                        Asia/Pyongyang

                        Asia/Qatar

                        Asia/Qostanay

                        Asia/Qyzylorda

                        Asia/Riyadh

                        Asia/Sakhalin

                        Asia/Samarkand

                        Asia/Seoul

                        Asia/Shanghai

                        Asia/Singapore

                        Asia/Srednekolymsk

                        Asia/Taipei

                        Asia/Tashkent

                        Asia/Tbilisi

                        Asia/Tehran

                        Asia/Thimphu

                        Asia/Tokyo

                        Asia/Tomsk

                        Asia/Ulaanbaatar

                        Asia/Urumqi

                        Asia/Ust-Nera

                        Asia/Vientiane

                        Asia/Vladivostok

                        Asia/Yakutsk

                        Asia/Yangon

                        Asia/Yekaterinburg

                        Asia/Yerevan

Now We have the list of all timezones in Asia. Let's set it e.g. to Asia/Qatar.

3. To change the timezone from Europe/Kiev to Asia/Qatar. just run 

[root@TEST-D01 ~]# timedatectl set-timezone Asia/Qatar

[root@TEST-D01 ~]# timedatectl

               Local time: Tue 2021-07-13 04:02:48 +03

           Universal time: Tue 2021-07-13 01:02:48 UTC

                 RTC time: Tue 2021-07-13 01:02:49

                Time zone: Asia/Qatar (+03, +0300)

System clock synchronized: no

              NTP service: n/a

          RTC in local TZ: no