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// The biggest 64bit prime
#define P 0xffffffffffffffc5ull
#define G 5

#include <stdio.h>
#include <stdint.h>
#include <assert.h>
#include <stdlib.h>

// calc a * b % p , avoid 64bit overflow

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Virtual Networking on Linux

In the Linux Kernel, support for networking hardware and the methods to interact with these devices is standardized by the socket API:

                +----------------+
                |   Socket API   |
                +-------+--------+
                        |
User space              |

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Understanding the Memory Layout of Linux Executables

Required tools for playing around with memory:

• hexdump
• objdump
• readelf
• xxd
• gcore

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Questions are not from any actual exam!!!  



Q:  Create a job that calculates pi to 2000 decimal points using the container with the image named perl
and the following commands issued to the container:  ["perl",  "-Mbignum=bpi", "-wle", "print bpi(2000)"]
Once the job has completed, check the logs to and export the result to pi-result.txt.

Solution:

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redirect.c

#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>

/**
 * Executes the command "grep Villanova < scores > out".

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Roll your own dynamic DNS service using Route53

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#!/bin/bash -eo pipefail

## Allows for creation of "Basic" DNS records in a Route53 hosted zone

function main() {
	record_name=$1
	record_value=$2

	[[ -z $record_name  ]] && echo "record_name is: $record_name" && exit 1
	[[ -z $record_value ]] && echo "record_value is: $record_value" && exit 1

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package main

import (
  "os"
  "strings"
)

func main() {
  const tmpl := `
USER={{.USER}}

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var crypto = require('crypto');

// larger numbers mean better security, less
var config = {
  // size of the generated hash
  hashBytes: 32,
  // larger salt means hashed passwords are more resistant to rainbow table, but
  // you get diminishing returns pretty fast
  saltBytes: 16,
  // more iterations means an attacker has to take longer to brute force an

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1. Execute make first. This will result in a netlinkKernel.ko output among many others.
2. Execute $ gcc netlinkUser.c -o netlinkUser
3. Insert kernel module by :$ sudo insmod netlinkKernel.ko      
4. Run ./netlinkUser to see message and run dmesg to see debug messages
5. Remove module by : $ sudo rmmod netlinkKernel          
6. Finally make clean to remove output files.