khenidak

#!/bin/bash
# What is this: it creates vxlan across two hosts
# does this need multicast on hosts: no, we are using the no learning approach
# How: we are using static popluation of fdb and arp database. (we don't use l2miss or l3miss - maybe we try it on a different script)
# What do i need:
#       two VMs running everywhere, as long as you can do udp between them.
#       modify host1/2 for host ips (your VMs)
#       modify ip1/ip2 and vip1/vip2 for your configuration.
#       the script connect to VMs via ssh. so make sure you have the keys handy
# what can i use it for: VMs/Containers/funky networking. get creative

khenidak

/* 
we depend on the discipline List<T> have (or not) arround allocating arrays 
if you are dealing with known length then modify to have a cap parameter and pre allocate your List<T>
*/
using System;
using System.Threading;
using System.Collections.Generic;

using System.Runtime.CompilerServices;

khenidak

don't do this at home!. This runs kernel 5.0.0 on Azure VM. The version itself is not certified yet to run on Azure.

Prep

Create VM on Azure follow https://docs.microsoft.com/en-us/azure/virtual-machines/linux/quick-create-cli

ssh to your new machine

Install prep req

khenidak

// src https://www.cs.cmu.edu/afs/cs/academic/class/15213-f99/www/class26/tcpserver.c
// modified to show the impact of bind(2) v listen(2) on tcp connection as visible by netstat -atp


/*
 * tcpserver.c - A simple TCP echo server
 * usage: tcpserver <port>
 */

#include <stdio.h>

khenidak

Foundation

Understanding ACID transactions https://www.essentialsql.com/sql-acid-database-properties-explained/

Understanding CAP theorem https://towardsdatascience.com/cap-theorem-and-distributed-database-management-systems-5c2be977950e

khenidak

git log  --pretty=format:"%h" <base branch>..<target branch> |  xargs -I {} git diff-tree  -v --name-status -r {}

khenidak

Create a nested development envrionment on Azure VM. I use this for kernel specific sandboxes/dev. Admittedly, This is following my own quirky dev env. So apprach this with care.

What will you have:

1. Separate virtual network for your sandbox
2. QEMU (kvm enabled) vms running using this network
3. Additional data disk aufs mounted for home directory (to move that disk to new vms if needed)

Steps

khenidak

<network>
  <name>kernel-net</name>
  <uuid>5618453a-d6af-42f5-b77d-eb1727371b73</uuid>
  <forward mode='nat'>
    <nat>
      <port start='1024' end='65535'/>
    </nat>
  </forward>
  <bridge name='kerneldevbr0' stp='on' delay='0'/>
  <mac address='42:ef:c9:0b:a4:f1'/>

khenidak

# on a debian system
# expects $1 as "<binary>:<package> <binary>:<package>"
# example "qemu-img:qemu-utils nslookup:dnsutils"
# if you are not sure which package has your binary
# use apt-file search <binary name>
# we don't handle error here. so make sure you are
# using the correct binary and package names in design time
ensure_tooling(){
    local req_tools=($1)
    for tool in "${req_tools[@]}"; do

khenidak

#Sources: 
# https://stackoverflow.com/a/28938235

# Reset
Color_Off='\033[0m'       # Text Reset

# Regular Colors
Black='\033[0;30m'        # Black
Red='\033[0;31m'          # Red
Green='\033[0;32m'        # Green