Ingress and Egress

Ingress and Egress are the network security features provided by network firewall.Ingress filtering, filters outside traffic from getting inside the network. Egress filtering, filters outgoing traffic before transmitting the data to another network.

Dropper

A program that launch viruses in a computer is a dropper. Dropping means Installing. Droppers are not files, it is a program that contains viruses. Trojan is a good example. Dropper viruses may go undetected because they are hidden, difficult to pinpoint and relatively uncommon. Droppers are also a relatively new type of virus that many anti-virus programs are not equipped to detect.

CGI programming with C, basic level

Common Gateway Interface(CGI) is one of the most popular way of creating dynamic websites. CGI is a server-side scripting language. It is an interface between The advantage of CGI is the applications can be written in any almost any language. A programmer familiar with C can create programs for CGI. It is common that Perl is usually used for CGI applications. Perl is simple and powerful language used for creating dynamic websites. It is not a strictly interpreted language.

In this post I am going to share my little experience with CGI programs using C in Linux platform( with root privileges). Not going too deeply into CGI or C, how it works?... etc. Just a demonstration

First of all you need a Apache server. Check is it available in your system and make sure that it is running. If it is available then just follow the steps below to start the server.

Armstrong numbers

An Armstrong(after Michael F. Armstrong) number, also known as Narcissistic number or pluperfect digital invariant(PPDI) OR plus perfect number, is a number that is sum of its own digits each raised to the power of the number of digits.

For example:
If the number is 371. How to find this number is an Armstrong number. First check the number of digit in this number. There are 3 digit, so take 3 as power.
Now,  3³=27
7³=343
1³ = 1
27+343+1=371
1634 is Armstrong or not?

Number Palindrome or not

A palindrome is a word, phrase, number, or other sequence of characters which reads the same backward or forward.  

A program

Simple Java program to Swap values

In this post, I would like to share two simple program which swap value stored in two variables. In the first program, uses an extra variable to perform swapping and in the second program there is no additional variable used. These two program uses two variable a and b to hold the values inserted by user. After processing the value in variables get replaced by each other. That is the value in a get replace by the value in b and the value in b get replaced by the value in a. For instance if user inserts 10 and 25 into the variable a and b respectively, after process the variable a will have 25 and b will have 10. To perform this operation, normally,we need an extra variable which holds the value in variable either the value in a or in b. If we store the value in a to the additional variable, say s, then we can replace a with b's value. Now, we have variable a

Apache Cordova Installation

Apache Cordova is a set of device APIs that allow a mobile app developer to access native device function such as the camera or accelerometer from JavaScript. Combined with a UI framework such as jQuery Mobile or Dojo Mobile or Sencha Touch, this allows a smartphone app to be developed with just HTML, CSS, and JavaScript.

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By using Apache Cordova APIs an app can be built without any native codes such Java or Objcetive-C etc. Cordova combines HTML,CSS3 and JavaScript to create the application package which same as the package developed using native code. The app developed can be published any respective market places

To develop the application usind Cordova requirs node.js platform download it from https://nodejs.org/ and install it. To test the installation use

node -v

in bash shell

node --version

in Windows Command line

Next Install a Git download it from http://git-scm.com/. It is used by Cordova in background. Install Cordova using npm(node package manager) utility of Node.js. Use the following command on Terminal

sudo npm install -g cordova

in Windows use

npm install -g cordova

To test Cordova type :

cordova -v

in terminal or

cordova --version

in Command Line Now add target platform. Android SDK for Android app and Xcode for iOS app. For Xcode, there are two ways :

• goto App Store:App store

• goto Apple Develper Downloads:AppleDownloader which requires registration as an Apple Developer. 

When Installation compelete, prepare Xcode for Cordova .Follow these: From the Xcode menu, select Preferences->Downloads tab. From the Components panel, press the Install button next to the Command Line Tools listing.iOS PLATFORM GUID

Inputting values in Java

Java uses Streams to perform I/O. Java I/O system links the streams to physical devices.For any I/O devices the bhaviour of stream is same. This means that the programmer does not need to specify difference between keyboard and monitor in coding . Java defines two types of streams.

• Byte streams
• Character streams

Byte streams provide a convenient way to handle input or output of bytes, that is, when reading or writing binary data. In Java, Byte stream are defined using two classes InputStream and OutputStream. The two most important methods that are, defined by this class, used for reading and writing of byte are :read() and write().
Character streams provide a convenient way to handle input or output of characters. In Java, Character stream are defined using two classes: Reader and Writer. These classes handle

Bytecode and JVM

Java is a most popular programming language. It follows Object Oriented Programming paradigm. The one of the reason for its popularity is Internet.Internet is a networks of networks connected together, which contains machines of different kind which have different architecture, different platforms. And above all Internet where its most terrific draw back is it security problem. In order to overcome all of the above versatile condition needed programming language whose programs should be portable, architectural and platform independent, and secured from attacks.

As it states that Java is compiled and interpreted language. The compiled code(program)

A little windowing

This post is gives you some knowledge about graphic mode programming, mainly about window programming, and its aspects. The programs used for graphic mode is  not like normal programs written for character mode. It has lot of function calls and callbacks. Today computer programming(GUI) is very easy. Programer don't need to worry about the internal working of the interfaces(such as window, control windows etc). But in reality these interface(A dialog box, a window) on display performs in a very interesting way. The programming paradigm for GUI based application are called event-driven programming

A computer programs can be in two mode :

• Character-mode
• Graphic-mode

In character mode computing, provides only minimal interface for the user. To

Persons to be remembered

• The Inventor of E-mail

             - V A Shiva Ayyadurai

• Father of Computing era/age

             - William Schickard

• Father of Computer

             - Charles Babbage

• World's first computer programer

             - Augusta Ada King (Ada lovelace)

• Inventor of WorldWideWeb

             - Tim Berners Lee

• Father of Internet

Database programming in VB for begginers

The built-in add-in tool ,Visual Data Manager, available in Visual Basic is used for creating database. Visual Data Manager can be used to create tables, add new data as well as edit data. Besides that, it can be used to modify table structure.

To create the database follow the steps

Step-1

 To activate or start  Visual Data Manager, select Add-In menu of VB project window from there select the first item, Visual Data Manager.On clicking the Visual Data Manager a window titled VisData will pop up. From the menu of  this window, click File and choose New to create a new database.(Steps:-New->Microsoft-Access->Version7.0MDB)

See the figures below:

Post Correspondance Problem(PCP)

To prove a program or normal thing(strings or languages) undecidable or decidable there are some technology. The technology is based on a very simple model of a computer called the Turing Machine. The Post Correspondence Problem is an undecidable problem that turns out to be a very helpful tool for proving problems in logic or in formal language theory to be undecidable.

What is undecidable?

The, specific, problem that cannot be solved using a computer are called undecidable. In computing there always exist some. That is a program and an input, whether the program will finish running or continue to run forever.

Suppose, we have step by step procedure(Algorithm) to solve a particular problem. We give the input(problem) and if that procedure can solve it, it gives the result true and if it not it give the result false. what if we give that procedure input(problem)which run forever that it take very long  time(years) to get the result(TRUE or FALSE), then we can't make the decision out of it. This situation is undecidable.

Interrupts

Interrupt can be termed as signal send by the hardware to processor. The signal tells that hardware is ready. When an interrupt signal comes, the processor stops or suspend what it is doing and give attention to the signal.

Processor is the central unit of a computer. Computer consist number of devices, input/output devices. Every devices are controlled and monitored by CPU. This is done by checking the status of every devices attached. For instance, CPU checks the status of the keyboard, printer, monitor to see if it is ready or not. Ready means if the user is typing, keyboard is ready and CPU give attention to device and if the user wants to print some thing CPU checks the status of the printer. If it is ready then execute some routine to perform the printing task.But the typing

Visual Basic 6: Using Microsoft DataGrid Control 6.0

DataGrid control is   which is not  available by default in Tool box of Vb. You can add it from by Selecting menu Project ->Component. From there select Microsoft DataGrid Control 6.0 and check check box to add it to Tool box. Before exiting from there, select the Microsoft ADO data control to access the database. Now you can drag and drop both conreol as other normal controls.  To create a Database one can use MS Access. After creating the DB use ADO control to connect the DB with the VB application

Click--> Visual Basic 6.0:Using Microsoft DataGrid Control 6.0

Combobox and click event in Visual Basic 6.0

Using VisualBasic I am creating a small application program. In this app contains a Text box, a combo-box and a list box. The app accept a number, through text-box, as a limit and by choosing an item (Factorial,Fibonacci,Prime) from the combo-box generate a list in the list box. For example if you feed 5 then choosing factorial from combo box will generate a series in the list box.
Normally you do insert code into the combo-box control by double clicking on it . It will by default shows an event-procedure like Sub Combo1_Change(). This means that by default combo-box generate an change event. But this change event is not going to show the result in list box. To show the result of selected item into the list box just change the event _Change to _Click which usually do by selecting the combo on the top of the code window

Sub Combo1_Change()
'code goes here
end sub
to
Sub Comb1_Click()
'code goes here
End sub.

Example:

This application has text box, combobox and a list box. Combo box contain three options Facorial Fibonacci and Prime. In the text box user can enter the limit up to which the user want to find, the choice from the combo box.

 Design

Click to Download the code

Creating Code modules in Visual Basic

Three VisualBasic(VB) Modules are:

• Form module
• Standard module
• Class module

In Visual Basic, a module is a part or a piece of code which, used to, perform some specific task . Modules is a  separate code file. In VB, for application development programmer normally insert code for application by double clicking on controls in desing mode. This action transfer the programmer from design window mode to code-window. The code usually contains declarations of variables, constants, types, procedures, functions event procedures etc etc. Visual Basic usually handles this as module for the form. By using VB module one can create common code for an entire application. Modules are helpful when programmer developing a large application which possibly involve the usage of same code at different part such as procedure,function. For instance a larger

Linker and Loader

Linker

Linker is a program whose task is linking various modules in a software. Usually programs are written in line by line. But, programs for large applications writing line by line is not a good idea. Developers divides the programs into various module. combining these modules gives the result. Developers write the code(source code) for each module. These code are compiled to get object files. So there are multiple source code and multiple object files. Here comes the benefit of linker. Linker combine all the object files which are compiled from source code and convert into final executable file/program.

    Sometime in linking of object files may include library files. All these files, object files library files combines into a single executable file sometime it can be an object file or library file.

Loader

Loader is a program whose task is to load programs. Normally, loader is a part of Operating System (OS). The task involves locating the program in secondary storage (sometime called offline storage or auxiliary memory such as Hard-disk drives) to main memory for executing. The program can be an application or sometimes an OS itself.