Arthur ArthurChiao

## elf_format_cheatsheet.md

      
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                x0nu11byt3
                / elf_format_cheatsheet.md
            
            
              Created
              February 27, 2021 05:26
            
              
                ELF Format Cheatsheet
              
          
    ELF Format Cheatsheet

Introduction

Executable and Linkable Format (ELF), is the default binary format on Linux-based systems.

Compilation


## kvm-host.c
#define _GNU_SOURCE
#include <asm/bootparam.h>
#include <errno.h>
#include <fcntl.h>
#include <linux/kvm.h>
#include <linux/kvm_para.h>
#include <stdarg.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>

## kcgroups.md

      
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                mcastelino
                / kcgroups.md
            
            
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              April 12, 2024 08:58
            
              
                Kubernetes and cgroups Resource Management/Static cpuManagerPolicy/Memory and Resource Isolation & Scheduling
              
          
    Overview

The goal of this document to cover all aspects of Kubernetes management, including how resources are expressed, constrained and accounted for. This started a way to ensure that alternate container runtime implementation like Kata containers will behave from a resource accounting and consumption point of view in the same manner as runc.
Location of the latest version of this document: https://gist.github.com/mcastelino/b8ce9a70b00ee56036dadd70ded53e9f
If you do not understand cgroups please refer to a quick primer at the bottom of this document. This will help you understand how the resource enforcement actually works.
Kubernetes Resource Management


## howto_bgp_ecmp_load_balancing.md

      
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                bufadu
                / howto_bgp_ecmp_load_balancing.md
            
            
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              March 2, 2024 19:13
            
              
                BGP ECMP Load Balancer
              
          
    How to build a load balancer with BGP and ECMP using VyOS

According to this cloudflare blog article "Load Balancing without Load Balancers", we can build a rock-solid load balancer only using a router. All the magic comes from BGP and Equal-Cost Multi-Path routing.
In this howto, I will use bird as BGP router on linux instance (ie. servers).
Test environment

I use GNS3 with this architecture :


## proc_net_tcp_decode
Decoding the data in /proc/net/tcp:

Linux 5.x  /proc/net/tcp
Linux 6.x  /proc/PID/net/tcp

Given a socket:

$ ls -l  /proc/24784/fd/11
lrwx------ 1 jkstill dba 64 Dec  4 16:22 /proc/24784/fd/11 -> socket:[15907701]

## sendRawEth.c
/*
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 */

#include <arpa/inet.h>
#include <linux/if_packet.h>
#include <stdio.h>
	#define _GNU_SOURCE
	#include <asm/bootparam.h>
	#include <errno.h>
	#include <fcntl.h>
	#include <linux/kvm.h>
	#include <linux/kvm_para.h>
	#include <stdarg.h>
	#include <stdint.h>
	#include <stdio.h>
	#include <stdlib.h>
	Decoding the data in /proc/net/tcp:

	Linux 5.x /proc/net/tcp
	Linux 6.x /proc/PID/net/tcp

	Given a socket:

	$ ls -l /proc/24784/fd/11
	lrwx------ 1 jkstill dba 64 Dec 4 16:22 /proc/24784/fd/11 -> socket:[15907701]
	/*
	* This program is free software: you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation, either version 3 of the License, or
	* (at your option) any later version.
	*/

	#include <arpa/inet.h>
	#include <linux/if_packet.h>
	#include <stdio.h>