The High availability clusters are computer clusters which are implemented mainly for the purpose of improving the availability of the services. The high availability clustering detect hardware/software faults, and instantly restart the application on another system without requiring administrative intercession, this process is commonly known as a Failover process. It has functionality that provides failover from one node to another if the current node becomes unavailable, a failover cluster appears on the network as a normal application, but it has additional functionality that increases its availability in case one server fail.

The clustering software may configure the node before starting the application on it. To run the system smoothly it require appropriate filesystems to be imported and mounted and  to set-up cluster rules that enable a common set of configurations also network hardware may have to be configured, and some supporting applications may need to be running as well.

Diagram: HA Cluster network (2 node)

The purpose of HA clusters to utilize all available techniques to make the individual systems/shared infrastructure as reliable as possible. The high availability clustering should include the following;

* Build redundancy into a cluster.

* Redundant network connections so that a switchover or network interface failures do not result in network outages.

* Disk mirroring to avoid system crashes in case of failure of internal disks.

* SAN data connections.

* Redundant electrical power inputs.

The high availability  clusters usually use a critical clustering in private network connection which is used to monitor the status of each node in the cluster. Such clustering are often required for critical databases,  business applications, file sharing on a network and customer services such as e-commerce websites.

Hello friends,

What is cryptography ?

Cryptography is the study of message protection in secret format. To most people, cryptography is concerned with keeping their communications private and secrete. The protection of sensitive communications has been the emphasis of cryptography throughout much of its history

There are two kinds of cryptography : symmetric and asymmetric. Symmetric cryptosystems use the same key (the secret key) to encrypt and decrypt a message, and Asymmetric cryptosystems use one key (the public key) to encrypt a message and a different key (the private key) to decrypt the encrypted message. Assymetric cryptosystems are also called public key cryptosystems.

Encryption is the transformation of data or message into a form that is as close to impossible as possible to read without the appropriate knowledge (a key; see below). Its purpose is to ensure privacy by keeping information hidden from anyone or unauthorise person, even those who have access to the encrypted data. Decryption is the reverse of encryption; it is the transformation of encrypted data back into an intelligible form.

Authentication is as fundamentally a part of our lives as privacy. Authentication is very necessary in our day to day life with any kind of transactions- when we sign our name to some document for instance - and, as we move to a world where our decisions and agreements are communicated electronically, we need to have electronic techniques for providing authentication. Cryptography provides mechanisms for such procedures. A digital signature.

Cryptography is central to the techniques used in computer and network security for such things as access control and information confidentiality. Cryptography is also used in many applications encountered in everyday life; the security of ATM cards, computer passwords, and electronic commerce all depend on cryptography.

Following are the TCP/IP Application protocols:
1.DHCP:

DHCP Dynamic Host Configuration Protocol is defined by RFC’s 2131
and 2132.DHCP is Dynamic Host Configuration
Protocol (DHCP) allows IP addresses to
be allocated to hosts on an as-needed basis.DHCP lets a host
‘borrow’ an IP address from a pool of IP addresses; when the
address is no longer required it is recycled and made available for
use by other host. DHCP also allows a host to retrieve a
verity of configuration information.

DCHP depends on UDP to carry packets between the client and server
tasks.

2. DNS

The DNS (Domain Name System) provides ondemand dynamic
translation between human-readable names (like www.mydoamin.com)
and the numeric addresses actually used by IP (like
192.169.10.28). The basics of DNS operation are defined in RFC’s
1034, 1101, 1876, 1982 and 2065.

A very widely-used implementation of DNS called BIND
(Berkeley Internet Name Domain)
DNS uses both UDP and TCP. It used UDP to carry simple queries and
responses but depends on TCP to guarantee the correct and orderly
delivery of large amounts of bulk data (eg zone configurations) across the network.

3. FTP

File Transfer Protocol (FTP) provides a mechanism for transfering data
files between various systems. In addition to the fundamental PUT and GET
operations, FTP provides a small number of file management and
user authentication facilities. FTP uses port 21

FTP depends on TCP to guarantee the correct and orderly delivery
of data across the network.

4. HTTP

Hyper Text Transfer Protocol (HTTP) is the protocol used to publish
Web pages across an internet. HTTP depends on TCP to guarantee the
correct and orderly delivery of data across the network.

5. IMAP

Interactive Mail Access Protocol (IMAP) allows clients to
manipulate email messages and mailboxes that reside on some server
machine. The current version of IMAP is Version 4, IMAP is more powerful
and more complex than the other widely-used mail-reading protocol
POP.

6. NFS

Network File System (NFS) allows files stored on one machine (the
“server”) to be accessed by other machines (the “clients”) as
though the files were actually present on the client systems. NFS
is defined in terms of a Remote Procedure Call (RPC) abstraction
which in turn formats its packets according to a
processor-independent eXternal Data Representation (XDR).

NFS is most often used over UDP. UDP does not guarantee packet delivery or ordering, so
when NFS runs over UDP the RPC implementation must provide its own
guarantees of correctness.

7. NNTP

Network News Transfer Protocol (NNTP) is used to propagate netnews
postings (including Usenet postings) between systems.

8. NTP

Network Time Protocol (NTP) is used to synchronise time-of-day
clocks between various computer systems. The current version of
NTP is Version 3, defined in RFC 1305.

9. POP

Post Office Protocol (POP) allows clients to read and remove email
from a mailbox that resides on some server machine. The current
version of POP is Version 3, usually referred to as POP3. POP uses port 110

10. Rlogin

Remote Login (rlogin) provides a network terminal or “remote
login” capability. Rlogin is similar to Telnet but it adds a
couple of features that make it a little more convenient than
Telnet.

11. Rsh

Remote Shell (rsh) is an r-command that provides for remote
execution of arbitrary commands. It allows you to run a command on
a server without having to actually log in on the server. More
importantly it allows you to feed data to the remote command and
retrieve the command’s output without having to stage the data
through temporary files on the server.

12. SMTP

Simple Mail Transfer Protocol (SMTP) is used to deliver email from
one system to another. The port used by SMTP is 25.
13. SNMP

Simple Network Management Protocol (SNMP) provides a means of
monitoring and managing systems over a network. SNMP defines a
method of sending queries (the GET and GET-NEXT primitives) and
commands (the SET primitive) from a management station client to
an agent server running on the target system, and collecting
responses and unsolicited event notifications.

14. Ssh

Secure Shell (ssh) provides remote login and execution features
similar to those of the rsh and rlogin r-commands, but ssh
encrypts the data that is exchanged over the network. Encryption
can protect sensitive information, and it is not uncommon for
security-conscious administrators to disable plain rsh and telnet
services in favour of ssh.

The SSH protocol used by the ssh command has also been used to
build a secure file transfer application which can be used as an
alternative to FTP for sensitive data.

15. Telnet

Telnet provides a network terminal or “remote login” capability.
The Telnet server accepts data from the telnet client and forwards
them to the operating system in such a way that the received
characters are treated as though they had been typed at a terminal
keyboard. Responses generated by the server operating system are
passed back to the Telnet client for display.

16. X Window System

The X Window System allows client programs running on one machine to control the graphic
display, keyboard and mouse of some other machine or of a
dedicated X display terminal.

enjoy…..:)

For installation of ioncube for perticular account then goto

http://www.ioncube.com/loaders.php

download it one server server where it is available. you need to do the following process on the server.

1 go to user directory and wget http://downloads.ioncube.com/loader_downloads/ioncube_loaders_lin_x86.tar.gz

2 Extract the tar file with tar -zxvf ioncube_loaders_lin_x86.tar.gz

3. change the permission chown user:user ioncube

4. then goto ioncube directory cd /home/user/ioncube and again change the ownership of all files to user:user

5.after changing the permission copy ioncube-encoded-file.php and ioncube-loader-helper.php in public_html by

cp ioncube-encoded-file.php ../public_html/

cp ioncube-loader-helper.php ../public_html/

6.then goto public_html folder of that user and again change the ownership to user:user for ioncube

7 Now ioncube is get installed you can access that using access ioncube by http://domain.com/ioncube-loader-helper.php

enjoy…..:)

Greetinngs,

Check out its feature on how it works.

–> There are several ways that SpamAssassin makes up its mind about a
message:
–> The message headers can be checked for consistency and adherence to
Internet standards (e.g., is the date formatted properly?).
–> The headers and body can be checked for phrases or message elements
commonly found in spam (e.g., “MAKE MONEY FAST” or instructions on how to be
removed from future mailings)-in several languages.
–> The headers and body can be looked up in several online databases that
track message checksums of verified spam messages.
–> The sending system’s IP address can be looked up in several online lists
of sites that have been used by spammers or are otherwise suspicious.
–> Specific addresses, hosts, or domains can be blacklisted or whitelisted.
A whitelist can be automatically constructed based on the sender’s past
history of messages.
–> SpamAssassin can be trained to recognize the types of spam that you
receive by learning from a set of messages that you consider spam and a set
that you consider non-spam. (SpamAssassin and the spam-filtering community
often refer to non-spam messages as ham. )
–> The sending system’s IP address can be compared to the sender’s domain
name using the Sender Policy Framework (SPF) protocol (http://spf.pobox.com)
to determine if that system is permitted to send messages from users at that
domain. This feature requires SpamAssassin 3.0.
–> SpamAssassin can privilege senders who are willing to expend some extra
computational power in the form of Hashcash.
Spammers cannot do these computations and still send out huge amounts of
mail rapidly. This feature requires SpamAssassin 3.0.

Most of SpamAssassin’s behavior is controlled through a systemwide
configuration file and a set of per-user configuration files. The per-user
configuration can also be stored in an SQL database.

How to Configure it ? : -
——————-

You can easily customize how SpamAssassin tags and identifies spam by
creating a spamassassin/user_prefs file. You can customize the number of
“spam points” required to identify a message as spam, create new rules, and
re-weight existing rules. Here is a sample user_prefs file. It raises the
threshold for identifying spam from 5 to 6, disables including spam warnings
in the subject and body, reweights a known rule, and adds several blacklist,
whitelist, and header rules.

Listing 1. A typical user_prefs configuration file

================================================================

#How many hits before a mail is considered spam?
required_hits 6

#Don’t mangle the messages so badly
rewrite_subject 0
use_terse_report 1

#whitelist and blacklist
whitelist_from *@www.zzzzzz.com
blacklist_from annoying-person@xyz.com

#reweight an existing rule
score BASE64_ENC_TEXT 3

#add some new rules
header KNOWN_LIST List-Id =~ /a-mailing-list-i-like/
score KNOWN_LIST -3

body EVITE /This invitation was sent to you by .* using Evite/
describe EVITE Looks like an eVite
score EVITE -3

================================================================

Enjoy..

Greetings,

If u want to lock a file with a password then you can do so using winrar. Almost all archives support giving password, including WinZip, 7-Zip and it’s not something special with WinRar. Bt WinRar is more comfortable then any other.
And if you are setting access like this, it is better you set the compression level to “Store”, which will make the compression and decompression faster, since the main aim here is to set a password.

1) Right click on the file for which u want the password to b put.
2) Click on “Add to Archive”.
3) Then go to Advanced tab.
4)Click on set password…choose your password.
5) Click ok.
6) A winrar file with your filename will be created.
7) Next u may delete the original file, as you have now compressed it with a password.
8) Anyone trying to open the rar file won’t be able to, unless he knows the password.

So, no needs of folder lock software.
Enjoy your privacy guys….