What is CentOS?
CentOS is an Enterprise Linux distribution based on the freely available sources from Red Hat Enterprise Linux. Each CentOS version is supported for 10 years (by means of security updates). A new CentOS version is released approximately every 2 years and each CentOS version is periodically updated (roughly every 6 months) to support newer hardware. This results in a secure, low-maintenance, reliable, predictable and reproducible Linux environment. Read more . . .
Posted by Gihan Kavinga Seneviratna at 8:24 AM
What is SE Linux
Simply SE Linux is a security layer that lies in between user and Linux kernel.For an example let's say that, you are going to access web site that runs on a SE Linux enabled server. First you need a web browser then you type the URL on the address bar, then it's search the DNS, .... and finally it will find the server ip. Once your request comes to the server it start some process for you with a unique id now you have some kind of connection to the server. From this step onward the server deal with your request. Without SE Linux the process runs on DAC (Discretionary Access Control ) mode. This means the user have the normal Linux file permission. In other words the user (who sent the request) log in as apache (default user for apache server ). This is not too bad because we can restrict user from editing files in server, but in most case it is not possible. Because we to write logs, upload files and many more to write to server, so in typical web server user apache have full permission to server root. What if some one upload a script to your server :-/ . But with SE Linux we can over come these kind of risks.
In SE Linux your request doesn't go through the server as in normal Linux. First it checks the DAC then it pass the request to MAC ( Mandatory Access Control ) layer. On the MAC layer it creates a context according to predefined policies. Now we have the full control over request (process).
Posted by B G Kavinga at 7:30 PM
As you know X window system eat most system resources in the machine.It's ok with my personal computer, but it deffer when it comes to a enterprise server.So by default any Ubuntu server doesn't come with X server. It's ok with experienced Linux users.But I have to work with other user who have no good knowledge of Linux. So I have to find a way to get X window system in Ubuntu server without using it's own resources.At last I decide to use backup server as a desktop environment for the server.Here how I configure it to server as a X server.
Posted by B G Kavinga at 11:14 AM
Introduction to javaJava is a programming language originally developed by James Gosling at Sun Microsystems (which has since merged into Oracle Corporation) and released in 1995 as a core component of Sun Microsystems' Java platform. The language derives much of its syntax from C and C++ but has a simpler object model and fewer low-level facilities. Java applications are typically compiled to bytecode (class file) that can run on any Java Virtual Machine (JVM) regardless of computer architecture. Java is a general-purpose, concurrent, class-based, object-oriented language that is specifically designed to have as few implementation dependencies as possible. It is intended to let application developers "write once, run anywhere" (WORA), meaning that code that runs on one platform does not need to be recompiled to run on another. Java is currently one of the most popular programming languages in use, particularly for client-server web applications, with a reported 10 million users.
Posted by B G Kavinga at 5:12 PM