The devices and comptuers connected to the Internet use a protocol called TCP/IP to communicate with each other. When a computer in New York wants to send a piece of data to a computer in England, it must know the destination IP address that it woud like to send the information to. That information is sent most often via two methods, UDP and TCP.

What is TCP?

TCP stands for Transmission Control Protocol. Using this method, the computer sending the data connects directly to the computer it is sending the data it to, and stay connected for the duration of the transfer. With this method, the two computers can guarantee that the data has arrived safely and correctly, and then they disconnect the connection. This method of transferring data tends to be quicker and more reliable, but puts a higher load on the computer as it has to monitor the connection and the data going across it. A real life comparison to this method would be to pick up the phone and call a friend. You have a conversation and when it is over, you both hang up, releasing the connection.

What is UDP?

UDP stands for User Datagram Protocol. Using this method, the computer sending the data packages the information into a nice little package and releases it into the network with the hopes that it will get to the right place. What this means is that UDP does not connect directly to the receiving computer like TCP does, but rather sends the data out and relies on the devices in between the sending computer and the receiving computer to get the data where it is supposed to go properly. This method of transmission does not provide any guarantee that the data you send will ever reach its destination. On the other hand, this method of transmission has a very low overhead and is therefore very popular to use for services that are not that important to work on the first try. A comparison you can use for this method is the plain old US Postal Service. You place your mail in the mailbox and hope the Postal Service will get it to the proper location. Most of the time they do, but sometimes it gets lost along the way.

Since TCP guarantees the delivery of data over a network we call it a connection-oriented protocol. If in the event that data isn’t sent correctly, the sending computer will be notified and will resend the information. This is compared to UDP, which doesn’t require that data has been received correctly. Likewise, we call UDP a connectionless protocol.

Link to complete article:

http://www.bleepingcomputer.com/tutorials/tutorial38.html

http://learn-networking.com/featured/how-the-transport-layer-works

The active Zenoss community forums have over 50,000 registered members that help each other with Zenoss Core installation, configuration, and trouble shooting. The community also shares ideas with each other on IT management best practices and enhance the overall solution with community-contributed management extensions.

Zenoss Core features include:

• Network, Server, and Application monitoring with a single product

• Ability to monitor any SNMP enabled device

• Real-time alerting when outages or slowdowns occur

• Single Event Console containing Zenoss alerts, SNMP traps, and log events

The solution has an open architecture with APIs for integrating with third party products (whether bringing data into Zenoss or exporting Zenoss data to other products).

How to Install Zenoss

Note: The installation of OS is not part of this how-to. The OS used in this How-to is Centos with default “server” selection and SELinux is disabled.
Log-in as root and run the following commands.

yum -y install mysql mysql-server net-snmp net-snmp-utils

Check if MySQL is running.
service mysqld status

If it is not running start it.
service mysqld start

You must change the root MySQL password from blank.
mysqladmin -u root password <newpassword>

Now test the password.
mysql -u root -p

It will ask for the new password.
newpassword

If you get the below prompt everything is fine.
mysql>

Exit out of MySQL.
exit

Download Zenoss

Go to /usr/scr/ and create a directory download

cd /usr/src

mkdir download

Go to zenoss download website and fill up the form then you can now download the software.

Here are the following softwares needed:

zenoss-1.1.2-0.rhel5.i386.rpm
zenoss-deps-rhel5-1.1.2.i386.tar.bz2
Unpack the deps.
tar xjf zenoss-deps.tar.bz2

cd to the zenoss-deps directory and install them.
rpm -Uvh *.rpm

cd to the zenoss RPM and install.
rpm -Uvh zenoss-1.1.2-0.rhel5.i386.rpm

Start snmpd.
/etc/init.d/snmpd start

Start zenoss.
/etc/init.d/zenoss start

If you have a firewall open port 8080 inbound accept.
iptables -I RH-Firewall-1-INPUT -p tcp –dport 8080 -j ACCEPT

Now open a browser (firefox) and go to.
http://example.com:8080

The default log-in is.
Username: admin
Password: zenoss

Note: Zenoss will only work with Firefox and IE7.0 or above.

Microsoft® Office 2010

The Move To The Browser

Most certainly a direct response to Google Apps, Microsoft is rolling out lightweight, FREE, Web browser versions of Word, PowerPoint, Excel and OneNote. All based in the cloud, the web-based versions of these products have fewer features than their desktop cousins but still give users basic tools to edit and change documents.

PowerPoint 2010

PowerPoint has been upgraded not only with a new browser version, but also a slew of bells and whistles have been added to the desktop version. Users now have the capability of editing video and images within PowerPoint with a basic video editing tool (not so different from the capabilities of iMovie) and an image editing tool, which is like a basic, simple version of Adobe Photoshop. Microsoft has also added the ability for users to launch a WebEx-like live sharing feature with other users. So if you create a slideshow in PowerPoint, you can share it with other people in real-time (which can be run on top of Sharepoint).

Here’s what the video editing tools look like in PowerPoint:

Excel 2010

Excel spreadsheets can now run in the browser, and similar to PowerPoint, spreadsheets can be published to the browser via the desktop version. The browser version of Excel has limited features, but offers more in-depth functionality than Google Spreadsheets. Microsoft has added a particularly innovative feature called Sparklines, which gives a visual snapshot image of a data trend over time within a cell. You can also share Excel via the browser with other users and set special permissions on who can access the document.

Here’s what the web version of Excel looks like:

Here’s the complete write up of Microsoft Office 2010 from Techcrunch.com

Movie for Microsoft Office: http://www.office2010themovie.com/

This is going to be a great event for those who are called to be a worship leader..

• Squid – is a proxy server and web cache daemon. It has a wide variety of uses, from speeding up a web server by caching repeated requests, to caching web, DNS and other computer network lookups for a group of people sharing network resources, to aiding security by filtering traffic.
• Dansguardian – written by SmoothWall Ltd and others, is content-control software: software designed to control which websites users can access. It also includes virus filtering and usage monitoring features.
• Clam AV – Clam AntiVirus (ClamAV) is a free, cross-platform antivirus software tool-kit capable of detecting many types of malicious software, including viruses. One of its main uses is on mail servers as a server-side email virus scanner.
• Bannerfilter -  is a redirect script for the Squid proxy server, designed to block advertising banners on the Web. Unlike most other solutions, it also automatically closes popup windows.
• SARG – Squid Analysis Report Generator is a tool that allow you to view “where” your users are going to on the Internet. Sarg provides many informations about Squid users activities: times, bytes, sites, etc…

Glad that I found this Tutorial from http://www.thedailyadmin.com

This was setup using vmware but definitely, you can install this even in a new PC. Just skip the vmware part.

Setup the Virtual Environment

Download and install VMWare Server (or whatever virtual environment you want). There are products available that will run on almost any operating system. I use VMWare Server 2.0 running on the main computer in our house (it is always on).

Install Ubuntu

Download the Ubuntu ISO

Install Ubuntu by mounting the ISO in the Virtual Server and following the prompts to install the default desktop. If you aren’t sure about what to choose, just accept the defaults.

Note: Set the IP address to a static address

Run APT Update to update the software packages cache
sudo apt-get update

Install Squid, ClamAV-daemon, Dansguardian, SARG, Apache2, Lynx

Install squid with the command
sudo apt-get install squid, clamav-daemon, dansguardian, sarg, apache2, lynx

Configure ClamAV-daemon by setting it to update the virus definitions automatically
sudo at 1:00 tomorrow
at>clamscan -i /home/username
>mail root@localhostat
> Enter
job 2 at Mon Mar 30 01:00:00 2009

You can verify that clam av is running by checking for the process
ps -ef | grep clamav

Configure Squid proxy server

Copy the file /etc/squid/squid.conf for a backup:
sudo cp /etc/squid/squid.conf /etc/squid/squid.conf.bak

Edit the squid.conf file
sudo vim /etc/squid/squid.conf

Search for the line TAG: visible_hostname
/TAG: visible_hostname

Move the cursor to the bottom line of that section after # none and hit the “i” key to insert the text
visible_hostname squid

Find the line # http_access allow localnet
and delete the # – this will allow for all clients on the local network to get to the Internet

Add a user named squid
sudo adduser squid

Restart the squid service
sudo /etc/init.d/squid restart

Install Bannerfilter

Download bannerfilter using wget
wget http://phroggy.com/files/unix/bannerfilter-1.31.tar.gz

Expand the archive
tar -zxvf bannerfilter-1.31.tar.gz

Make a bannerfilter directory
sudo mkdir /etc/squid/bannerfilter

Move the bannerfilter folder
mv bannerfilter-1.31/* /etc/squid/bannerfilter

Make a bannerfilter directory
sudo mkdir/var/www/bannerfilter

Move the www contents to the /var/www/bannerfilter
sudo mv /etc/squid/bannerfilter/www/* /var/www/bannerfilter

You should now be able to browse http://ip_address/bannerfilter

Test that the redirector.pl script is functioning
sudo perl /etc/squid/bannerfilter/redirector.pl

Type in something like “hello world” and you should see hello world printed to the screen, hit CTRL+C

Edit the squid.conf file again
sudo vim /etc/squid/squid.conf

Add the following line to the end of the squid.conf
redirect_program /var/www/bannerfilter/redirector.pl

Then restart the Squid service
sudo /etc/init.d/squid restart

Configure your browser to use the proxy settings

Internet Explorer: Go to Tools->Options->Connection-Lan Settings and check the box for “Use a proxy server for your LAN…) then type the address of the Virtual Machine (my case 172.26.1.10) and set the port to 3128(this is the port that dansguardian uses). Check the box for Bypass proxy server for local addresses

Firefox – Tools->Options->Advanced->Network tab->Settings. Select Manual proxy configuration and set the HTTP proxy to the IP address of the Virtual Machine and the port to 3128. Check the box “use this proxy for all protocols

Go to http://127.0.0.1/test.html to see if the proxy works

Run the /update.sh script to update the data files
cd /etc/squid/bannerfilter
sudo ./update.sh

Schedule bannerfilter for auto-updates
sudo crontab -e

Add the line 0 12 * * * /etc/squid/bannerfilter/update.sh

Save the file and quit vim

To test if bannerfilter is working go to a site with a lot of ads (like about.com) and if you see the words “Blocked” in what would be an advertisement spot then it works

Configure Dansguardian

The main configuration for Dansguardian is located in /etc/dansguardian/dansguardian.conf
sudo vim /etc/dansguardian/dansguardian.conf

Change the line accessdeniedaddress = ‘http://ip_address/cgi-bin/dansguardian.pl ‘ to the local IP address that was assigned to the Ubuntu virtual machine

Add a # in front of the line:
UNCONFIGURED – Please remove this line after configuration

Restart dansguardian:
sudo /etc/init.d/dansguardian

Configuring the browser to use Dansguardian by going back into the browser settings and change the proxy port from 3128 to 8080

Installing SARG (with Webmin)

I have found that SARG works best if you have a web interface. I like to use webmin for this.

To install the Webmin dependancies
sudo apt-get install perl libnet-ssleay-perl openssl libauthen-pam-perl libpam-runtime libio-pty-perl libmd5-perl

Download Webmin
wget http://prdownloads.sourceforge.net/webadmin/webmin_1.340_all.deb

Install webmin
sudo dpkg -i webmin_1.340_all.deb

Set the password for Webmin
sudo /usr/share/webmin/changepass.pl /etc/webmin root password

Browse to the webmin interface to check the reporting by browsing to http://ip_address:10000 where ip_address is the IP of the Ubuntu virtual machine

The following list is the features that should be working

* Keyword blocking
* Advertisement blocking
* URL blocking
* Antivirus
* Caching
* Reporting

The Biblegateway website offers 90 Days Reading Challenge. It’s an online Bible reading. You will be presented with different Books, Chapters and Verses in the Bible good for 90 Days.

The Bible in 90 Days reading challenge begins today!

If you’ve ever wanted to read through the entire Bible but didn’t know where to begin, here’s your chance: a reading plan that walks you through the entire Bible from start to finish in three months. It’s a summer reading challenge that could actually change your life.

Getting started with the Bible in 90 Days plan is easy, and you can do it right here at BibleGateway.com. Just visit (and bookmark) the Bible in 90 Days daily reading page and go there for each day’s Bible reading. You can subscribe to the readings via RSS or iCal by clicking on the links to the right of the daily reading. (If you want to use a different Bible version with the Bible in 90 Days plan, you can choose a different Bible from the dropdown menu above the daily reading.)

If you want to delve even deeper this summer, there’s more to the Bible in 90 Days challenge than just the reading plan—at the Bible in 90 Days website you’ll find resources to involve your entire church in the experience. If you want to share the challenge with your congregation or small group, the tools there will help you do so.

How to use the Bible Gateway reading plans

Using a reading plan is simple. Just go to the daily reading page and read the daily Scripture passage displayed there. There are four different plans you can choose from, and each takes a different route through the Bible over the course of a year. (Read more about the four reading plans.) Select the reading plan you want and your preferred Bible version from the drop-down menu at the top of the page and press “Update” to refresh the page with your new reading plan settings.

If you miss a day (or want to read ahead), you can use the calendar in the top right to navigate forward or backward through your plan.

URL: http://www.biblegateway.com/resources/readingplans/index.php

cat /etc/slackware-verison

To check the cpu information:

cat /proc/cpuinfo

To check the memory info:

cat /proc/meminfo

• Backup – Protect your data
• Restore – Recover your lost files easily
• Copy Open Files – Backup live documents
• Versioning – Keep previous versions
• Incremental Backups – Does what is required
• FTP and Email – Online access
• Performance & Throttling – As fast as can be
• Synchronize – Work with 2 or more computers
• Secure – Keep confidential data private
• Compression – Keep your files small
• Automation – Set it and forget it
• Advanced Customization – A superb array of options
• Vista and 64-bit Compatible – Tested and optimized for Vista

Why Backup?

Every day individuals, businesses, and organizations lose their precious files due to a drive failure, inadvertent deletion, or other unwanted action or event. The result is a great deal of stress, anxiety, and in the case of businesses, lost revenue.

The computer hard drive that stores all your data has moving parts, and in time your hard drive will wear out and fail. It’s just a matter of when. You need to keep a copy of all your important data somewhere else.

Jakobshavn has doubled its speed in the past 15 years, draining increasing amounts of ice from the Greenland ice sheet into the ocean, and Holland, an oceanographer at New York University, has been trying to find out why. Scientists like him are more than a little astonished at the rate at which our planet’s frozen frontiers seem to be responding to global warming. The crucial question, though, is what will happen over the next few decades and centuries.

That’s because the fate of the planet’s ice, from relatively small ice caps in places like the Canadian Arctic, the Andes and the Himalayas, to the immense ice sheets of Greenland and Antarctica, will largely determine the speed and extent of sea level rise. At stake are the lives and livelihoods of hundreds of millions of people, not to mention millions of square kilometres of cities and coastal land, and trillions of dollars in economic terms.

In its 2007 report, the Intergovernmental Panel on Climate Change (IPCC) forecast a sea level rise of between 19 and 59 centimetres by 2100, but this excluded “future rapid dynamical changes in ice flow”. Crudely speaking, these estimates assume ice sheets are a bit like vast ice cubes sitting on a flat surface, which will stay in place as they slowly melt. But what if some ice sheets are more like ice cubes sitting on an upside-down bowl, which could suddenly slide off into the sea as conditions get slippery? “Larger rises cannot be excluded but understanding of these effects is too limited to assess their likelihood,” the IPCC report stated.

Even before it was released, the report was outdated. Researchers now know far more. And while we still don’t understand the dynamics of ice sheets and glaciers well enough to make precise predictions, we are narrowing down the possibilities. The good news is that some of the scarier scenarios, such as a sudden collapse of the Greenland ice sheet, now appear less likely. The bad news is that there is a growing consensus that the IPCC estimates are wildly optimistic.

The oceans are already rising. Global average sea level rose about 17 centimetres in the 20th century, and the rate of rise is increasing. The biggest uncertainty for those trying to predict future changes is how humanity will behave. Will we start to curb our emissions of greenhouse gases sometime soon, or will we continue to pump ever more into the atmosphere?

Even if all emissions stopped today, sea level would continue to rise. “The current rate of rise would continue for centuries if temperatures are constant, and that would add about 30 centimetres per century to global sea level,” says Stefan Rahmstorf of the Potsdam Institute for Climate Impact Research in Germany. “If we burn all fossil fuels, we are likely to end up with many metres of sea level rise in the long run, very likely more than 10 metres in my view.”

This might sound dramatic, but we know sea level has swung from 120 metres lower than today during ice ages to more than 70 metres higher during hot periods. There is no doubt at all that if the planet warms, the sea will rise. The key questions are, by how much and how soon?

To pin down the possibilities, researchers have to look at what will happen to all the different contributors to sea level under various emissions scenarios. The single biggest contributor to sea level rise over the past century has been the melting of glaciers and ice caps outside of Greenland and Antarctica, from Alaska to the Himalayas. According to one recent estimate, the continued loss of this ice will add another 10 to 20 centimetres to sea level by 2100. It cannot get much worse than this: even if all this ice melted, sea level would only rise by about 33 centimetres.

Read the full article ..

RAID can be implemented by software in the host, but this is not usually successful. It is best implemented by microcode in the storage subsystem controller. The various types of RAID are explained below. In the diagrams, the square box represents the controller and the cache.

Parity is a means of adding extra data, so that if one of the bits of data is deleted, it can be recreated from the parity. For example, suppose a binary halfword consists of the bits 1011. The total number of ’1′s in the halfword is odd, so we make the parity bit a 1. The halfword then becomes 10111. Suppose the third bit is lost, the halfword is then 10?11. We know from the last bit that there should be an odd number of ’1′s, the number of recognisable ’1′s is even, so the missing but must be a ’1′. This is a very simplistic explanation, in practice, disk parity is calculated on blocks of data using XOR hardware functions. The advantage of parity is that it is possible to recover data from errors. The disadvantage is that more storage space is required.

RAID0 -  is simply data striped over several disks. This gives a performance advantage, as it is possible to read parts of a file in parallel. However not only is there no data protection, it is actually less reliable than a single disk, as all the data is lost if a single disk in the array stripe fails.

RAID1 – is data mirroring. Two copies of the data are held on two physical disks, and the data is always identical. RAID1 has a performance advantage, as reads can come from either disk, and is simple to implement. However, it is expensive, as twice as many disks are needed to store the data.

RAID2 -  is a theoretical entity. It stripes data at bit level across an array of disks, then writes check bytes to other disks in the array. The check bytes are calculated using a Hamming code. Theoretical performance is very high, but it would be so expensive to implement that no-one uses it.

RAID3 – A block of data is striped over an array of disks, then parity data is written to a dedicated parity disk. Successful implementations usually require that all the disks have synchronised rotation. RAID3 is very effective for large sequential data, such as satellite imagery and video.

In the gif above, the right hand disk is dedicated parity, the other three disks are data disks.

RAID4 – data is written in blocks onto the data disks (i.e. not striped), then parity is generated and written to a dedicated parity disk.

RAID5 – data is written in blocks onto data disks, and parity is generated and rotated around the data disks. Good general performance, and reasonably cheap to implement. Used extensively for general data.

The gif below illustrates the RAID5 write overhead. If a block of data on a RAID5 disk is updated, then all the unchanged data blocks from the RAID stripe have to be read back from the disks, then new parity calculated before the new data block and new parity block can be written out. This means that a RAID5 write operation requires 4 IOs. The performance impact is usually masked by a large subsystem cache.
As Nat Makarevitch pointed out, more efficient RAID-5 implementations hang on to the original data and use that to generate the parity according to the formula new_parity = old_data XOR new_data XOR old_parity. If the old data block is retained in cache, and it often is, then this just requires one extra IO to fetch the old parity. Worst case it will require to read two extra data blocks, not four.

RAID 5 often gets a bad press, due to potential data loss on hardware errors and poor performance on random writes. Some database manufactures will positively tell you to avoid RAID5. The truth is, it depends on the implementation. Avoid software implemented RAID5, it will not perform. RAID5 on smaller subsystems will not perform unless the subsystem has a large amount of cache. However, RAID5 is fine on enterprise class subsystems like the EMC DMX, the HDS USP or the IBM DDS devices. They all have large, gigabyte size caches and force all write IOs to be written to cache, thus guaranteeing performance and data integrity.

Most manufactures will let you have some control over the RAID5 configuration now. You can select your block stripe size and the number of volumes in an array group.
A smaller stripe size is more efficient for a heavy random write workload, while a larger blocksize works better for sequential writes. A smaller number of disks in an array will perform better, but has a bigger parity bit overhead. Typical configurations are 3+1 (25% parity) and 7+1 (12.5% parity).

RAID6 – is growing in popularity as it is seen as the best way to guarantee data integrity as it uses double parity. It was originally used in SUN V2X devices, where there are a lot of disks in a RAID array, and so a higher chance of multiple failures. RAID6 as implemented by SUN does not have a write overhead, as the data is always written out to a different block.

The problem with RAID6 is that there is no standard method of implementation; every manufacturer has their own method. In fact there are two distinct architectures, RAID6 P+Q and RAID6 DP.

DP, or Double Parity raid uses a mathematical method to generate two independent parity bits for each block of data, and several mathematical methods are used. P+Q generates a horizontal P parity block, then combines those disks into a second vertical RAID stripe and generates a Q parity, hence P+Q. One way to visualise this is to picture three standard four disk RAID5 arrays then take a fourth array and stripe again to construct a second set of raid arrays that consist of one disk from each of the first three arrays, plus a fourth disk from the fourth array. The consequence is that those sixteen disks will only contain nine disks worth of data.

P+Q architectures tend to perform better than DP architectures and are more flexible in the number of disks that can be in each RAID array. DP architectures usually insist that the number of disks is prime, something like 4+1, 6+1 or 10+1. This can be a problem as the physical disks usually come in units of eight, and so do not easily fit a prime number scheme.

RAID7 – is a registered trademark of Storage Computer Corporation, and is basically RAID3 with an embedded operating system in the controller to manage the data and cache to speed up the access.

RAID1+0 – is a combination of RAID1 mirroring and data striping. This means it has very good performance, and high reliability, so its ideal for mission critical database applications. All that redundancy means that it is expensive.

RAID50 – is implemented as a RAID5 array that is then striped in RAID0 fashion for fast access

RAID53 – applies this ‘RAID then stripe’ principle to RAID3. It should really be called RAID3+0. Both these RAID versions are expensive to implement in hardware terms

RAID0+1 – is implemented as a mirrored array whose segments are RAID 0 arrays, which is not the same as RAID10. RAID 0+1 has the same fault tolerance as RAID level 5. The data will survive the loss of a single disk, but at this point, all you have is a striped RAID0 disk set. It does provide high performance, with lower resilience than RAID10.

RAID-S – or parity RAID is a specific implementation of RAID5, used by EMC. It uses hardware facilities within the disks to produce the parity information, and so does not have the RAID5 write overhead. It used to be called RAID-S, and is sometimes called 3+1 or 7+1 RAID.

RAIDZ is part of the SUN ZFS file system. It is a software based variant of RAID5 which does not used a fixed size RAID stripe but writes out the current block of data as a varying size RAID stripe. With standard RAID, data is written and read in blocks and several blocks are usually combined together to make up a RAID stripe. If you need to update one data block, you have to read back all the other data blocks in that stripe to calculate the new RAID parity. RAIDZ eliminates the RAID 5 write penalty as any read and write of existing data will just include the current block. In a failure, data is re-created by reading checksum bytes from the file system itself, not the hardware, so recovery is independent of hardware failures. The problem, of course is that RAIDZ closely couples the operating system and the hardware. In other words, you have to buy them both from.

Article and Images from – http://www.lascon.co.uk/d008005.htm