Posted: January 19th, 2012 | Author: adq890 | Filed under: general | No Comments »
Q. What is data center tiers? What is tier 1 data center? Which tier / level is the best for maximum uptime?
A. Tier 1 to 4 data center is nothing but a standardized methodology used to define uptime of data center. This is useful for measuring:a) Data center performance
b) Investment
c) ROI (return on investment)Tier 4 data center considered as
most robust and less prone to failures. Tier 4 is designed to host mission critical servers and computer systems, with fully redundant subsystems (cooling, power, network links, storage etc) and compartmentalized security zones controlled by biometric access controls methods. Naturally, the simplest is a Tier 1 data center used by small business or shops.
- Tier 1 = Non-redundant capacity components (single uplink and servers).
- Tier 2 = Tier 1 + Redundant capacity components.
- Tier 3 = Tier 1 + Tier 2 + Dual-powered equipments and multiple uplinks.
- Tier 4 = Tier 1 + Tier 2 + Tier 3 + all components are fully fault-tolerant including uplinks, storage, chillers, HVAC systems, servers etc. Everything is dual-powered.
Data Center Availability According To Tiers
The levels also describes the availability of data from the hardware at a location as follows:
- Tier 1: Guaranteeing 99.671% availability.
- Tier 2: Guaranteeing 99.741% availability.
- Tier 3: Guaranteeing 99.982% availability.
- Tier 4: Guaranteeing 99.995% availability.
source : http://www.cyberciti.biz/faq/data-center-standard-overview/
Posted: January 18th, 2012 | Author: adq890 | Filed under: general | No Comments »
THE FUTURE IS FOREVER
6 JUNE 2012
Major Internet service providers (ISPs), home networking equipment manufacturers, and web companies around the world are coming together to permanently enable IPv6 for their products and services by 6 June 2012.
Organized by the Internet Society, and building on the successful one-day World IPv6 Day event held on 8 June 2011, World IPv6 Launch represents a major milestone in the global deployment of IPv6. As the successor to the current Internet Protocol, IPv4, IPv6 is critical to the Internet’s continued growth as a platform for innovation and economic development.
Posted: December 27th, 2011 | Author: adq890 | Filed under: apache, centos | redhat | fedora, config | No Comments »
Installing Modevasive
mod_evasive is an evasive maneuvers module for Apache to provide evasive action in the event of an HTTP DoS or DDoS attack or brute force attack. It is also designed to be a detection tool, and can be easily configured to talk to ipchains, firewalls, routers, and etcetera.
-> Execute the following commands to install it:
#wget http://www.zdziarski.com/projects/mod_evasive/mod_evasive_1.10.1.tar.gz
#tar -xzvf mod_evasive_1.10.1.tar.gz
#cd mod_evasive
#/usr/sbin/apxs -cia mod_evasive20.c
#rm -rf /root/mod_evasive*
-> Test to make sure it was loaded:
#grep -i evasive /etc/httpd/conf/httpd.conf
Next, edit /etc/httpd/conf/httpd.conf and uncomment (remove the # in front of each line) the following:
<IfModule mod_evasive.c>
DOSHashTableSize 3097
DOSPageCount 5
DOSSiteCount 100
DOSPageInterval 2
DOSSiteInterval 2
DOSBlockingPeriod 600
</IfModule>
-> Restart Apache by executing the command
#/etc/init.d/httpd restart
Info
—-
- DOSHashTableSize: is the size of the table of URL and IP combined
- DOSPageCount: is the number of same page requests from the same IP during an interval that will cause that IP to be added to the block list.
- DOSSiteCount: is the number of pages requested of a site by the same IP during an interval which will cause the IP to be added to the block list.
- DOSPageInterval: is the interval that the hash table for IPs and URLs is erased (in seconds)
- DOSSiteInterval: is the intervale that the hash table of IPs is erased (in seconds)
- DOSBlockingPeriod: is the time the IP is blacked (in seconds)
- DOSEmailNotify: can be used to notify by sending an email everytime an IP is blocked
- DOSSystemCommand: is the command used to execute a command when an IP is blocked. It can be used to add a block the user from a firewall or router.
- DOSWhiteList: can be used to whitelist IPs such as 127.0.0.1
Although mod_dosevasive can be quite effective in some cases, in others it can cause more problems by blocking non-offending IPs. It is suggested you take a look at hardware solution if you.
Source : http://www.zdziarski.com/blog/?page_id=442
Source : http://sabarish4u.wordpress.com/2008/11/21/157/
