1. Use different open source projects like Linux, Solaris, Firefox, Filezilla, Apache HTTP Server, Gaim, and others.

2. Look for a place to contribute. This means not only programming, but also documentation, theme design, art work, or architectural design.

3. Note that each project has its own distinct methods for communication and submitting contributions.

4. Join the mailing list. This is highly recommended because you will never feel that you are left behind. You can also get feedback on patches and contributions.

5. Respect and maintain discussions.

6. Encourage contributions.

7. Start small by reporting and fixing bugs.

8. Submitting small patches containing bug fixes.

9. Respond and send feedback.

10. If you really want to help but don’t have the experience or the know-how, DONATE! By giving a few dollars to help out open source developers, you can help them get the tools they need to build better programs.

Also read, http://www.kegel.com/academy/opensource.html

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Step 2
On the right top of the new screen you will see a link titled “Themes”
Click on this link.

Step 3
There are about thirty different themes to choose from. Try different ones out and see which you like best. Some of them will even change during the day. Others are tapped into your location and will change as the weather changes. As you click each choice, you should see the background/theme change automatically.

Step 4
Once you have chosen the Gmail theme or background you would like to use, simply click on your inbox. The change to the background is saved automatically.

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To understand the benefit of mandatory access control (MAC) over traditional discretionary access control (DAC), you need to first understand the limitations of DAC.

Under DAC, ownership of a file object provides potentially crippling or risky control over the object. A user can expose a file or directory to a security or confidentiality breach with a misconfigured chmod command and an unexpected propagation of access rights. A process started by that user, such as a CGI script, can do anything it wants to the files owned by the user. A compromised Apache HTTP server can perform any operation on files in the Web group. Malicious or broken software can have root-level access to the entire system, either by running as a root process or using setuid or setgid.

Under DAC, there are really only two major categories of users, administrators and non-administrators. In order for services and programs to run with any level of elevated privilege, the choices are few and course grained, and typically resolve to just giving full administrator access. Solutions such as ACLs (access control lists) can provide some additional security for allowing non-administrators expanded privileges, but for the most part a root account has complete discretion over the file system.

A MAC or non-discretionary access control framework allows you to define permissions for how all processes (called subjects) interact with other parts of the system such as files, devices, sockets, ports, and other processes (called objects in SELinux). This is done through an administratively-defined security policy over all processes and objects. These processes and objects are controlled through the kernel, and security decisions are made on all available information rather than just user identity. With this model, a process can be granted just the permissions it needs to be functional. This follows the principle of least privilege. Under MAC, for example, users who have exposed their data using chmod are protected by the fact that their data is a kind only associated with user home directories, and confined processes cannot touch those files without permission and purpose written into the policy.

SELinux is implemented in the Linux kernel using the LSM (Linux Security Modules) framework.

Type Enforcement involves defining a type for every subject, that is, process, and object on the system. These types are defined by the SELinux policy and are contained in security labels on the files themselves, stored in the extended attributes (xattrs) of the file. When a type is associated with a processes, the type is called a domain, as in, “httpd is in the domain of httpd_t.” This is a terminology difference leftover from other models when domains and types were handled separately.

All interactions between subjects and objects are disallowed by default on an SELinux system. The policy specifically allows certain operations. To know what to allow, TE uses a matrix of domains and object types derived from the policy. The matrix is derived from the policy rules. For example, allow httpd_t net_conf_t:file { read getattr lock ioctl }; gives the domain associated with httpd the permissions to read data out of specific network configuration files such as/etc/resolv.conf. The matrix clearly defines all the interactions of processes and the targets of their operations.

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2. Now type ‘list volume’.

This command will list out all the drives of your computer with their label,size letter etc

3.Now lets say you want to hide volume 2 then you should type ‘Select volume 2′ i.e select volume ‘drive number’.

this command will select the volume you want to hide,remember the drive not hidden till yet.

4.Now lets say for e.g for hiding the volume 2,you have to type this command ‘Remove letter D’ the letter D is the letter assigned to volume 2,the letter assigned are different for different volumes.

Note-Your drive is hidden now it may take a restart to be in effect.The drive can be retrieve back easily just by following step 1 to 3 and instead of step 4 follow step 5.

5.To unhide your drive follow step 1 to 3 and then step 5..just type ‘assign letter D’,here letter D is just an example.

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A relational database stores the data in the form of tables and columns. A table is the category of data, like Employee, and the columns are information about the category, like name or address.

Some databases have minimal feature sets and only store data, while others include programming languages, facilities and utilities to support enterprise-level applications like ERP and data warehousing. Oracle is the #1 database and has the most advanced feature set.

Oracle is made up of a set of processes running in your operating system. These processes manage how data is stored and how it is accessed. I will cover these processes in detail in the future; but for now we just need to understand that Oracle is a program that is running in the background, maintaining your data for you and figuring out where it should go on your hard drive.

In almost all relational databases, data is accessed through SQL, or Structured Query Language, and Oracle is no exception. SQL allows you to SELECT your data, INSERT new records, UPDATE existing records and DELETE records you want to get rid of. SQL can be embedded in other languages or you can run scripts of SQL directly against the database.

PL/SQL is the procedural language extension to SQL. PL/SQL is a programming language like C, Java or Pascal. In the Oracle world, there is no better way to access your data from inside a program. SQL can be natively embedded in PL/SQL programs. I will be using both SQL and PL/SQL very heavily in my future articles.

PL/SQL is a feature-rich language geared toward developing database applications. PL/SQL is the procedural language of the database, but it is also the procedural language for most of Oracle’s tools. Programs that run inside the database are called stored procedures. These stored procedures are almost always PL/SQL, but can be written in Java.

Some of Oracle’s tools to access the database and create programs are:

SQL*Plus has a command line interface. With it, you can access the database and write stored procedures, you can run SQL commands to retrieve data and you can run scripts of either SQL, PL/SQL or built-in SQL*Plus commands, or a mixture of those three things.

Oracle Developer is a 4GL GUI application Builder. With Developer, you can create forms, reports, and graphics. Oracle*Forms and Oracle*Reports are two components of Oracle Developer. Earlier versions created client-server applications, but the more recent versions create web applications that run under the Oracle Application Server (OAS). OAS is a web-based application server sold by Oracle. OAS is licensed separately and is very expensive (as are its closed source competitors). The current version is OAS 10g.

HTML DB is a fairly new application builder geared toward web development (added to the DB with release 9iR2). HTML DB does not need an application server. This tool runs from the database and can be presented to the web using the Apache web server that comes with the database. Since this is not an additional license, it provides a cheaper way to develop applications. Developer is a feature-rich thick client with all of the normal GUI widgets. HTML DB is HTML-based and is very thin and limited to the HTML provided widgets.

Oracle Enterprise Manager (OEM) is the Enterprise GUI tool to manage the database. From this tool, you can perform any action in the database that is required. This tool is primarily used for administration but can also be provided to developers for application tuning and monitoring. In Oracle 10g, OEM also provides Grid control.

There are also a lot of third party tools for accessing the database. For our purposes, our primary tool for data access will be SQL*Plus. In the future, I will cover creating applications with HTML DB and accessing your data with some choice third-party tools.

How about Java? Java is the current hot language, especially on the web. I will also be covering Java in the database in future articles. Java is natively supported by Oracle. Technically, you could use Java to create your stored procedures if you chose, but I am not a proponent of that. When you are working inside the database, I believe that you should only resort to Java when you cannot accomplish a task in PL/SQL. As you’ll see, there is very little you cannot accomplish with PL/SQL.

It will be hard to learn Oracle if you can’t play with it. So where can you get access to this software? Oracle has a technical web site called OTN (Oracle Tech Net) that provides access to all of Oracle’s software and all of the documentation for that software. There are also forums and many other tools to use to help you learn Oracle. You have to register to access it, but registration is free. Go to http://otn.oracle.com/ and get an ID today. In future articles, I will be spending a lot of time accessing this web site to download software and documentation. My next article will cover downloading Oracle 10g and installing it.

As a side note, Oracle provides all of their software with a developer’s license. This license allows you to try out the software free of charge. You may not create production applications without a paid license, but development with the tools is acceptable. I am not a lawyer, so I recommend that you review the license when you download any software from OTN.

Also, a note about versioning in Oracle; all products released by Oracle have a version. The current version of the database is 10g Release 1, also written as 10gR1. In addition to this semantic release name, each release has a numeric version. The numeric release for 10gR1 is 10.0.1.3.

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• The month and year when your created your Gmail / Google Account. You can look at the last page of your Gmail Inbox (or go to Sent Items) to get an approximate idea of the date when you created the account.
• If you created a Gmail account by invitation, write the email address of the person who first sent you that invite for Gmail. Use a search query like “in:all has invited you to open a free Gmail account” to find that invitation email
• The names of any custom labels that you may have created in your Gmail account.
• The day/month/year when you started using various other Google services (like AdSense, Orkut, Blogger, etc.) that are associated with the Google account that you are trying to recover. If you’re not certain about some of the dates, provide your closest estimate*.

[*] For Analytics, look at the first date when it started collecting stats for your website(s). For Orkut, look at the last page of your scrapbook. For AdSense, you may take the help of your AdSense account manager.

#4. It goes without saying but do not use the same password for your main Google / Gmail account and your secondary email address.

#5. If you access Gmail and other Google services over a wifi network, make sure that you always use the secure url’s like https://gmail.com. Go to Gmail settings and set ‘Browser Connection’ to ‘Always use https.’ This might make your Gmail access a bit slower but your account will be more secure.

#6. Once in a while, do refer to that little line in the footer section of your Gmail Inbox that shows the different IP addresses from where your account is being accessed. If you find an unknown IP address, change your Google password immediately. The person who hacked my Gmail accounts configured them with his Hotmail account so he could effectively read all my email communication remotely from his Hotmail inbox without ever logging into my Google account again. I could figure that out only after I saw an IP address from a Microsoft server in my Gmail activity log.

#7. You should also consider copying emails from Gmail to another service (like Yahoo! Mail or Hotmail – it is effortless) so when your Gmail account is compromised, you at least have access to all your previous emails. Or you can configure a desktop email client like Outlook or Thunderbird with your Gmail account (via POP3 or IMAP) and thus you’ll have an automatic offline backup of your gmail inbox.

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LDAP, Lightweight Directory Access Protocol, a directory service internet protocol runs over Transmission Control Protocol/Internet Protocol (TCP/IP) that that email and other programs use to look up information from a server.

Every email program has a personal address book, but how do you look up an address for someone who’s never sent you email? How can an organization keep one centralized up-to-date phone book that everybody has access to?

That question led to development of a standard called DIRECTORY SERVICES which supports the capability to locate certain types of information easily, efficiently, and quickly.

A directory is a set of objects with attributes organized in a logical and hierarchical manner. A simple example is the telephone directory, which consists of a list of names (of either persons or organizations) organized alphabetically, with each name having an address and phone number associated with it.

For example, the entry for Peter Chan might have the following attributes:

cn: Peter Chan

mail: peter@ust.hk

telephoneNumber: 2358-1234

telephoneNumber: 2358-4321

roomNumber: 2228

Lightweight Directory - Directories are kind of like a database but not really. A directory is a specialized

database that is optimized for lookups. Unlike a traditional RDBMS, LDAP is not designed to show

complex relationships between relations. Imagine if 99% of your actions on were going to be simple

"selects", and you wanted anyone, anywhere to be able to do these selects over the Internet. This is

where LDAP excels. Examples of directories are the TVGuide, the phone book, a library card

catalog, and DNS.

"Give me the phone number of John Smith."

"Give me all the tv shows that are on tonight on the Sci-Fi channel."

Access Protocol - LDAP is an outgrowth of the x.500 standard. LDAP is an open standard,

unlike many other proprietary directory solutions. Most of the directory-like solutions that were

out on the market are now very similar to LDAP. Some of these solution providers, Sun and

 Microsoft specifically, have designed JNDI and ADSI APIs so that you can connect with any

 kind of directory service. This is kind of like ODBC or JDBC is to an RDBMS.

Cool things you can do with LDAP

-Contact Management

-Users and Security

-Image storage

-Document Management

-Store business logic - actual code or SQL statements

tements

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Zombie

After the zombie is removed, its process id and entry in the process table can then be reused but until its entry is in the process table that value cannot be used for other process in case the parent spawns the new process. It will allocate a new pid different from that of zombie process to the new process created.

Zombies can be identified in the output from the ps command in Linux by the presence of a “Z” in the “STAT” column.

To remove zombies from a system, the SIGCHLD signal can be sent to the parent manually, using the kill command. If the parent process still refuses to reap the zombie, the next step would be to remove the parent process. When a process loses its parent, init becomes its new parent. Init periodically executes the wait system call to reap any zombies with init as parent.

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Configuring a squid proxy is an easy task and allows you with wide number of options to configure your users access to the internet .
The best part is that squid is supported on all open source platforms
In this article I will explain on how to configure squid proxy server on redhat / linux.

For configuring squid server we first we need to install squid rpm
Step: 1)
#rpm –ivh squid-2.6.STABLE-5.el5_1.3.i386.rpm

You can also use yum repository for installation . If your system doesnot provide you can configure the yum server for your own

For how to configure yum server read this
After configuring yum server install the squid rpm using
#yum –y install squid

Step2:) Open the squid main configuration file :

#vim /et c/squid/squid.conf

This is the main configuration file which holds all the squid settings and controls.
Step3:) Squid , by default runs on port 3128. If we need to change the web proxy port.
In the file search for http_port 3128 and change it to http_port 8080.
Now your squid web proxy will run on port 8080.

Step4:) Next you need access rules for the proxy server which are known as ACL to limit users’ ability to browse the Internet. Squid matches each Web access request it receives by checking the http_access list from top to bottom. If it finds a match, it enforces the allow or deny statement and stops reading further. You have to be careful not to place a deny statement in the list that blocks a similar allow statement below it. The final http_access statement denies everything, so it is best to place new http_access statements above it

Here are some examples of the ACL

¬
Restricting web access by IP address
acl mylan src 172.24.0.0/16
http_access allow mylan
Restricting web access by phrase in the url
acl myphrase url_regex phrase
http_access deny myphrase
To read more about using squid acl click here.
Step 5:) Like every linux application squid needs to be restarted for changes to the configuration file can take effect..

# service squid restart

For enabling squid startup after the reboot:

#chkconfig squid on

You need to force users to use your proxy server by configuring the proxy setting in the web browser.
To add the setting in the browser read this
Now you can add an extra layer of security and reduce internet bandwidth charges.

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