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Smashing the Stack for fun

Netcat a hackers tool

This is one of the best tool I have ever used for any work related to networks. There are so many functionalities which netcat provides. A few of them being are given below

  • Outbound or inbound connections, TCP or UDP, to or from any ports
  • Can read command line arguments from standard input
  • Full DNS forward/reverse checking, with appropriate warnings

    • A simple example of netcat would be demonstrated below. In our case the server will be listening on 3490 and the client will be connecting to 5000 port. Though this possibility of man in the middle attack is difficult but not impossible. This is just for demonstration purpose as to how netcat can be used for modfying the data. We assume that connection ports are modified accordingly.

    Server is in listening mode
    shrikar@shrikar-desktop:~/test$ ./server
    server: waiting for connections...

    Netcat will be sitting in between the server and client . The swab is a program which does a simple thing of modifying every occurance of 'H' with 'B'.
    nc -l -p 5000 0 < bp | tee bef | nc localhost 3490 | ./swab | tee rec 1 >bp

    On the client side we will can see that the Occurance of 'H' is modified to 'B'

    This is cool!!!!

    shrikar@shrikar-desktop:~/test$ ./client localhost
    client: connecting to 127.0.0.1
    client: received 'Bello, world!'

     

    Sample swab Program
    #include < stdio.h >
    int main(int argc, char** argv) {
    int c;
    while ((c = fgetc(stdin)) != EOF) {
    if ( c == 'H')
    c='B';
    fputc(c, stdout);
    fflush(stdout);
    }
    }

    Source

Undergraduate Projects

  • Message Passing Interface

    • This Project involved the setting up of cluster and then writing parallel application to show the benefits of Parallel programs over the generic single flow program. This also involved the implementation of bully algorithm to decide who is the master among the cluster. The newly elected master would then distribute the work to individual slaves and get the work done. To show the application of parallel program computationally intensive fractals were generated on the fly using the same cluster setup. This project helped us a lot to understand the parallel programs,cluster and their advantages and applications in the real world.

  • Application Of Ncurses and Datastructure

    • This is a text editor with a menu driven interface using the ncurses library. Provides features of a standard editor. It has been developed for the Unix environment. This supports text mode graphics.

  • Unix Shell

    • Provides an overview of how the processes are created with the fork and the exec system call and how the shell can be implemented by these functions.

  • Paint

    • Similar to MS Paint Brush Application implemented using Turbo C. Provides basic features for the graphics and uses the standard graphics library. Menu driven interface with mouse support has been implemented.