Gildas Le Drogoff gildas-ld

How to Generate & Use Private Keys using OpenSSL's Command Line Tool

These commands generate and use private keys in unencrypted binary (not Base64 “PEM”) PKCS#8 format. The PKCS#8 format is used here because it is the most interoperable format when dealing with software that isn't based on OpenSSL.

OpenSSL has a variety of commands that can be used to operate on private key files, some of which are specific to RSA (e.g. openssl rsa and openssl genrsa) or which have other limitations. Here we always use

My Elasticsearch cheatsheet with example usage via rest api (still a work-in-progress)

Shortlinks:

Cluster Health
- Index Level
- Shard Level
Nodes Overview
Indices Overview
Cluster Maintenance

Google Public NTP [AS15169]:

time.google.com

time1.google.com

time2.google.com

time3.google.com

Journalctl Cheat Sheet

Configuration

Permissions

To see messages from other users and the system as well as performing various log operations from a regular user add it to the group:

sudo usermod -aG systemd-journal $USER

MongoDB Cheat Sheet

Show All Databases

show dbs

Show Current Database

Setting up Prettier and ESLint with pre-commit hook

Initialize Git repository
```
git init
```
Create .gitignore file and add the following:
```
node_modules/
*.env
```

	### 1: Drop invalid packets ###
	/sbin/iptables -t mangle -A PREROUTING -m conntrack --ctstate INVALID -j DROP

	### 2: Drop TCP packets that are new and are not SYN ###
	/sbin/iptables -t mangle -A PREROUTING -p tcp ! --syn -m conntrack --ctstate NEW -j DROP

	### 3: Drop SYN packets with suspicious MSS value ###
	/sbin/iptables -t mangle -A PREROUTING -p tcp -m conntrack --ctstate NEW -m tcpmss ! --mss 536:65535 -j DROP

	### 4: Block packets with bogus TCP flags ###

	# Gawk version
	# Remote
	grep -v "rem_address" /proc/net/tcp \| awk '{x=strtonum("0x"substr($3,index($3,":")-2,2)); for (i=5; i>0; i-=2) x = x"."strtonum("0x"substr($3,i,2))}{print x":"strtonum("0x"substr($3,index($3,":")+1,4))}'

	# Local
	grep -v "rem_address" /proc/net/tcp \| awk '{x=strtonum("0x"substr($2,index($2,":")-2,2)); for (i=5; i>0; i-=2) x = x"."strtonum("0x"substr($2,i,2))}{print x":"strtonum("0x"substr($2,index($2,":")+1,4))}'

	# No Gawk
	# Local
	grep -v "rem_address" /proc/net/tcp \| awk 'function hextodec(str,ret,n,i,k,c){

	# __
	# .--------.--.--.-----.-----.\| \|
	# \| \| \| \|__ --\| _ \|\| \|
	# \|__\|__\|__\|___ \|_____\|__ \|\|__\|
	# \|_____\| \|__\|
	#
	# e x e r c i s e s

	# Important: Remember to add a semi-colon at the end of each query.

	# Default config for sway
	#
	# Copy this to ~/.config/sway/config and edit it to your liking.
	#
	# Read `man 5 sway` for a complete reference.
	exec wal -R

	#notifications
	exec mako
	exec mailnag