schrodyn

ELF Format Cheatsheet

Introduction

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

Compilation

schrodyn

About

• I faced bandwidth issues between a WG Peer and a WG server. Download bandwidth when downloading from WG Server to WG peer was reduced significantly and upload bandwidth was practically non existent.
• I found a few reddit posts that said that we need to choose the right MTU. So I wrote a script to find an optimal MTU.
• Ideally I would have liked to have run all possible MTU configurations for both WG Server and WG Peer but for simplicity I choose to fix the WG Server to the original 1420 MTU and tried all MTUs from 1280 to 1500 for the WG Peer.

Testing

• On WG server, I started an iperf3 server
• On WG peer, I wrote a script that does the following:
  • wg-quick down wg0
• Edit MTU in the /etc/wireguard/wg0.conf file

schrodyn

#!/usr/bin/env python
import argparse
import binascii
import hashlib
import os
import re
import sys
import traceback

__author__  = "Jeff White [karttoon] @noottrak"

schrodyn

!pe
.exr -1 `last exception
!sos.pe `last clr exception
!dso  `dump stack object
.chain 

.load sos

schrodyn

NEWLINE=$'\n'
PROMPT="[%(?:%{$fg_bold[green]%}quack :%{$fg_bold[red]%}quack )%{$reset_color%}(%T) "
PROMPT+='%{$fg[cyan]%}%c%{$reset_color%}$(git_prompt_info)'
PROMPT+="]${NEWLINE}"
PROMPT+="➜ "

ZSH_THEME_GIT_PROMPT_PREFIX=" %{$fg_bold[blue]%}git:(%{$fg[red]%}"
ZSH_THEME_GIT_PROMPT_SUFFIX="%{$reset_color%}"
ZSH_THEME_GIT_PROMPT_DIRTY="%{$fg[blue]%}) %{$fg[yellow]%}✗"
ZSH_THEME_GIT_PROMPT_CLEAN="%{$fg[blue]%})"

schrodyn

• macOS, Zsh, and more
  • Zsh initializations
  • Zsh way of $PATH
  • the special macOS
  • /usr/libexec/path_helper
    • What is it?
    • What does it do?
    • What does it break?
  • Situation explained

• The .*shrc file

schrodyn

import time
from typing import List
import pefile
from capstone import *
from capstone.x86 import *
import re
import struct

# SAMPLE_PATH = 'bin/enc_string_test.bin32'
SAMPLE_PATH = 'bin/2cd2f077ca597ad0ef234a357ea71558d5e039da9df9958d0b8bd0efa92e74c9.bin32'

schrodyn

I run this on my server called 'empty'.

Assuming you've done a git clone or a git pull of the code...

Switch to the release you want to build:

[dan@empty:~/librenms] $ export RELEASE=1.56
[dan@empty:~/librenms] $ git checkout master
[dan@empty:~/librenms] $ git pull
[dan@empty:~/librenms] $ git checkout tags/$RELEASE  

schrodyn

union PE_BASE {
  PVOID baseAddress;
  IMAGE_DOS_HEADER *mz;
  IMAGE_NT_HEADERS *pe;
};

union PE_BASE64 {
  PVOID baseAddress;
  IMAGE_DOS_HEADER *mz;
  IMAGE_NT_HEADERS64 *pe;

schrodyn

#!/bin/sh

# only used for ports in poudriere.conf:ALLOW_MAKE_JOBS_PACKAGES
# ALLOW_MAKE_JOBS_PACKAGES="pkg llvm* openjdk*"
MAKE_JOBS_NUMBER=4

DEFAULT_VERSIONS+=ssl=libressl
DEFAULT_VERSIONS+=python=2.7 python2=2.7 python3=3.6
DEFAULT_VERSIONS+=mysql=10.2m
DEFAULT_VERSIONS+=samba=4.6