CentOS Web panel

CentOS has introduced a free Web Hosting control panel (CWP : Centos Web Panel) which is designed for easy management of servers including both Dedicated & VPS without the help of ssh console.

During installation procedure, CWP installs full LAMP stack (apache, php, phpmyadmin, webmail, mailserver etc.) on your server.

List of softwares installed and configured during CWP installation are as below:

Apache Web Server
PHP 5.4
MySQL + phpMyAdmin
Postfix + Dovecot + roundcube webmail
CSF Firewall
Backups; AutoFixer for server configuration
Varnish Cache server
suPHP & suExec
Mod Security + OWASP rules
Monitor services eg. top, apache stats, mysql etc.

In this article, let’s have a check with the server requirements and features of CWP in Linux servers. Continue reading…

The extra second in June 30, 2015 – The Leap Second !

The International Earth Rotation & Reference Systems Service (IERS) has mentioned that an extra second is to be added to Coordinated Universal Time (UTC) at 23:59:59 on 30 June 2015 and this is to make sure the alignment of astronomical and atomic time.

Coordinated Universal Time, UTC is one of the basic time conventions used by most of the world’s local time zones. This UTC time convention has been derived from a bunch of atomic clocks that are distributed across several countries globally.

The rotation of our earth is not so constant and it changes a bit over time and in-turn it decreases the mean rotation speed slowly. This is the exact cause behind leap seconds that gets added up to the UTC time scale, as they adjust the process of the UTC time itself to scale the real earth rotation.

This 1 second adjustment have hardly affected the normal human lives till now. But high performance timekeeping is most important for scientific and economic computing because even a second interruption may become stunningly important in these technologies. This scenario was last observed in 2012 when a second was added to the world time. Websites like Foursquare, Reddit, LinkedIn suffered glitches as the extra second got added because their system clocks were unable to figure out the sudden change.

In fact, on June 30, 2015 when the clock stuck 23:59:60, this will cause problems to many scientific and economic computing systems which are not programmed for this additional time. As conventional computing systems depend on precise time by using the Network Time Protocol (NTP) to be in match with the world’s atomic clocks, issues are expected, as many systems are not programmed for this extra leap second.

The International Earth Rotation and Reference System Service (IERS) in Paris, France observes the time between earth’s rotation and the atomic time. When the difference between the two approaches 0.9 seconds, they order a leap second to be added worldwide.

The workaround for this in our Linux machines is to reboot the server before the leap second period and then execute “date -s now” command in the server so as to update the leap second in the server.