Change Time Zone from Command line | CentOS | RHEL | Ubuntu | Fedora


As you all know, It is very easy to change Time Zone using Graphical Interface but this article will help you change TimeZone Using command line.

Time Zone

I have tested these steps on CentOS / RHEL and Ubuntu, Please comment down below if doesn’t work for you.

Please follow these steps as root or with root equivalent sudo rights:

  • Check Time Zone using following command
    [root@tejas-barot-linux-ahmedabad ~]# date
  • First Remove symbolic link of current time zone
     [root@tejas-barot-linux-ahmedabad ~]# rm /etc/localtime
  • Let’s Change the Time Zone from Command line
    [root@tejas-barot-linux-ahmedabad ~]# ln -sf /usr/share/zoneinfo/Asia/Kolkata /etc/localtime

Note : You can find your time zone under /usr/share/zoneinfo/

Disable rate-limiting in rsyslog v5 | Linux | RHEL | CentOS | Ubuntu


First of all extremely sorry for not being active as I was busy with some work, Now back to the blogging.

This article will show you how to disable rsyslog rate-limiting, But You can also use rate-limiting according to your requirement.

How to use rate limiting in rsyslog?

This article is tested with rsyslog 5.7.1 on Fedora 13. It will not work with version of rsyslog prior to 5.7.1.

In rsyslog 5.7.1 we introduced rate limiting. This is a option for the Unix Socket Input module called imuxsock. In short, this option limits the amount of messages written into logfiles by a process, if the process tries to write huge amounts of messages in a short period of time.

To Read more Visit :


If you are receiving error messages like below in /var/log/messages

imuxsock begins to drop messages from pid 5923 due to rate-limiting 

Please following below method to stop / disable rate-limiting in rsyslog in version 5.

Note: rsyslog version 7 has this disabled by default but rsyslog version 5 has this enabled.

To disable it, add following parameters to your /etc/rsyslog.conf , You need to add with root user or root equivalent user.

$SystemLogRateLimitInterval 0
$SystemLogRateLimitBurst 0

Execute following command to restart rsyslog services

service rsyslog restart

Linux: The GHOST Vulnerability | RHEL | CentOS

The GHOST vulnerability is a serious weakness in the Linux glibc library. It allows attackers to remotely take complete control of the victim system without having any prior knowledge of system credentials. CVE-2015-0235 has been assigned to this issue.


Qualys security researchers discovered this bug and worked closely with Linux distribution vendors. And as a result of that we are releasing this advisory today as a co-ordinated effort, and patches for all distribution are available January 27, 2015.


What is glibc?

The GNU C Library or glibc is an implementation of the standard C library and a core part of the Linux operating system. Without this library a Linux system will not function.


What is the vulnerability?

During a code audit Qualys researchers discovered a buffer overflow in the __nss_hostname_digits_dots() function of glibc. This bug can be triggered both locally and remotely via all the gethostbyname*() functions. Applications have access to the DNS resolver primarily through the gethostbyname*() set of functions. These functions convert a hostname into an IP address.


Ghost Vulnerability
Ghost Vulnerability



What is the risk?

There is a remote code execution risk due to this vulnerability. An attacker who exploits this issue can gain complete control of the compromised system.


Is the risk real?

During our testing, we developed a proof-of-concept in which we send a specially created e-mail to a mail server and can get a remote shell to the Linux machine. This bypasses all existing protections (like ASLR, PIE and NX) on both 32-bit and 64-bit systems.


What can be done to mitigate the risk?

The best way to mitigate the risk is to apply a patch from your Linux vendor. Qualys has worked closely with Linux distribution vendors and patches are available as of today January 27, 2015.


Why is it called the GHOST vulnerability?

It is called as the GHOST vulnerability as it can be triggered by the GetHOST functions.


Is this a design flaw?

No. This is an implementation problem in the affected versions of the software.


What versions and operating systems are affected?

The first vulnerable version of the GNU C Library affected by this is glibc-2.2, released on November 10, 2000. We identified a number of factors that mitigate the impact of this bug. In particular, we discovered that it was fixed on May 21, 2013 (between the releases of glibc-2.17 and glibc-2.18). Unfortunately, it was not recognized as a security threat; as a result, most stable and long-term-support distributions were left exposed including Debian 7 (wheezy), Red Hat Enterprise Linux 6 & 7, CentOS 6 & 7, Ubuntu 12.04, for example.


Where can I download the exploit?

We want to give everyone enough time to patch. According to our data once the vulnerability has reached its half-life we will release the exploit. Half-life is the time interval measuring a reduction of a vulnerability’s occurrence by half. Over time, this metric shows how successful efforts have been to eradicate vulnerability. A shorter half-life indicates faster remediation. Half-life was originally coined by Qualys in the Laws of Vulnerability.


Qualys customers can detect GHOST by scanning with the Qualys Vulnerability Management (VM) cloud solution as QID 123191. This means that Qualys customers can get reports detailing their enterprise-wide exposure during their next scanning cycle, which allows them to get visibility into the impact within their organization and efficiently track the remediation progress of this serious vulnerability.



Qualys Advisory:




Oracle Enterprise Linux:



GNU C Library:


Link to Original Article :

Hope this will be helpful to you all.

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SAR GUI: Export sar / sysstat reports as PDF using kSar


If you are Linux Administrator you must know what SAR is, sar is a very useful utility for Linux Administrators to get the report of CPU Usage and You can monitor I/O, CPU Usage, Idle system state using sar utility. This article will help you to read / export sar reports in Graphical mode.

In this HowTo, I will show you how you can export sar reports as PDF / JPG / PNG using kSar tool.

ksar - PDF
ksar – PDF

In RHEL / CentOS you will find sar reports under /var/log/sa

In Ubuntu / Debian based Linux you will find sar reports under /var/log/sysstat

Perform following steps to export sar report:

1. Make Sure Java is installed on your system to open kSar Utility.

2. Download kSar Utility from below URL

3. Extract / Unzip Downloaded file

root@tejas-barot-linux-ahmedabad:~/Downloads# unzip

4. Give Executable permission to kSar.jar

root@tejas-barot-linux-ahmedabad:~/Downloads/kSar-5.0.6# chmod +x kSar.jar

5. Execute below command to open java file (kSar.jar):

root@tejas-barot-linux-ahmedabad:~/Downloads/kSar-5.0.6# java -jar kSar.jar

6. Now Click on Data -> Load from Text file…

7. Provide Path of sar reports path:

For RHEL: /var/log/sa/sarXX
For Debian/Ubuntu: /var/log/sysstat/sarXX

8. Select “Export to PDF / JPG / PNG” from Data  To Export sar report as PDF / JPG / PNG

Enjoy Sysstat Monitoring 🙂 Enjoy GUI Reports 🙂 Enjoy Linux 🙂 Enjoy Open Source 🙂

This is how you can export sar reports in Graphical format.

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MySQL: Drop all tables from Database using Script / Linux


Few days back, I got a task to do, Task was Keep the database as it is, So that we do not have to add database users, privileges and everything again and again, Just Drop all the databases tables inside the database. If there are only few tables like 5 or 10 than it is easy to do it manually, but what if you have the 100s or 1000s of tables inside database ?

I was in same situation, there were more than 500 tables and  I need to drop it quickly as it was production server, So for the same I managed to do it easily by using few command line parameters and loop, After that I have created script for the same which helps me to drop those tables very easily, You don’t have to worry about each and every table, It will keep database as it is but will drop all the tables from the selected database.

I am sharing that script and steps how to use that script, Would request you to test on non production environment first, Wherever you are executing this script its totally on your risk.

MySQL Script
MySQL Script


SUGGESTION: Take a Backup of your database / tables / MySQL Before executing Script, So if anything goes wrong you can also recover.

Steps to execute script :-

1. Download Script

tejas-barot@linux-ahmedabad:~$ wget

2. Give executable permissions

tejas-barot@linux-ahmedabad:~$ chmod +x

3. Now Let’s execute Script

tejas-barot@linux-ahmedabad:~$ ./

4. Provide name of the MySQL database from which you want to drop all the tables.

Enter Database name:                         <—- Provide Database name here
Enter MySQL root Password:          
<—- Provide root password of MySQL Here

5. Script will take a Full database backup into /tmp, but I would request don’t depend on this, before executing script take backup.

6. That’s it wait for few minutes, It will drop all the tables from MySQL Database.

Enjoy MySQL 🙂 Enjoy Linux 🙂 Enjoy Open Source 🙂

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