Linux System Administration

Linux Kernel

Linux kernel provides an abstraction hardware layer for an Android. This allows an Android to be ported into variety of different devices. Furthermore the linux kernel is used for android's memory management, process management, netwoking and other underlined operating systems services.

Native Libraries

These shared libraries are pre-installed on a android device by each vendor. They are written in C/C++ language and allow 3D and 2D graphics, window manager, all sorts audio video formats, Sqllite database and etc.

Android Runtime

This layer includes Dalvik Virtual machine code and core Java Libraries.

Application Framework

Android Application framework is a high-level layer to provide a developer with a space for a new Android applications development.

Applications and Widgets

This is the highest level of the Android system architecture. End user android applications and widgets layer.

Android system architecture

Android system architecture

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If you would ever need to shield your website from a public access, know that apache .htaccess file provides a simple and yet powerful way to accomplish it. This article teaches you just that in simple to follow steps.

As a first step we need to make sure that our website configuration will read .htaccess files. To do that check your httpd.conf file or your website apache setting whether it contains a directive:

 AllowOverride ALL

On a Ubuntu / Debian system this directive defaults to “none”.

Options Indexes FollowSymLinks MultiViews
AllowOverride ALL
Order allow,deny
allow from all

If have made some changes restart your apache web server:

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Author: Jaroslav Imrich

apache mod SSLThis article describes configuration techniques of module mod_ssl, which extends a functionality of Apache HTTPD to support SSL protocol. The article will deal with authentication of server (One-way SSL authentication), as well as it will also include authentication of clients by using certificates (Two-way SSL authentication).


If you have decided to enable a SSL ( Secure Sockets Layer ) protocol on your web server it may be because you would like to extend its functionality to achieve an integrity and confidentiality for a data transferred on unsecured networks. However, this protocol with the combination of PKI ( Public Key Infrastructure ) principles can also along the side of integrity and confidentiality provide authentication between both sides involved in the client-server communication.

One-way SSL authentication allows a SSL client to confirm an identity of SSL server. However, SSL server cannot confirm an identity of SSL client. This kind of SSL authentication is used by HTTPS protocol and many public servers around the world this way provides services such as webmail or Internet banking. The SSL client authentication is done on a “application layer” of OSI model by the client entering an authentication credentials such as username and password or by using a grid card.

Two-way SSL authentication also known as mutual SSL authentication allows SSL client to confirm an identity of SSL server and SSL server can also confirm an identity of the SSL client. This type of authentication is called client authentication because SSL client shows its identity to SSL server with a use of the client certificate. Client authentication with a certificate can add yet another layer of security or even completely replace authentication method such us user name and password.

In this document, we will discuss configuration of both types of SSL authentication one-way SSL authentication and two-way SSL authentication.

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