nguyen127001

openssl 🔐

Install

Install the OpenSSL on Debian based systems

sudo apt-get install openssl

Adding SFTP-only user to Ubuntu Server

To add a SFTP-only user, you'll need to make sure your SSH config settings are correct, add a new user/group and set permissions for your new user. For step-by-step directions, see below. Omit sudo if you're logged in as root.

Directions

Edit /etc/ssh/sshd_config and make sure to add the following at the end of the file:
```
 Match group filetransfer
```

ChrootDirectory %h

Override the entrypoint in docker-compose.yml for the MariaDB Docker container by adding:

entrypoint: mysqld_safe --skip-grant-tables --user=mysql

The start up the Docker Compose stack:

$> docker-compose up -d

Then login to the Docker container:

Introduction

I often find myself ssh'ing into my servers and checking my systemd service logs with $ journalctl -f -u {name}.service. One day I got tired of this and wanted all of my important logs in once place (Amazon AWS Cloudwatch). To my dismay, there weren't any real good tutorials on how to do so. So, voilà.

Steps

Overall, it's a fairly simple process consisting of the following few steps.

1. Modify the service file

Open the service file with $ sudo vi /lib/systemd/system/{name}.service

Modify the [Service] section:

Nginx TLS SNI routing, based on subdomain pattern

Nginx can be configured to route to a backend, based on the server's domain name, which is included in the SSL/TLS handshake (Server Name Indication, SNI).
This works for http upstream servers, but also for other protocols, that can be secured with TLS.

prerequisites

at least nginx 1.15.9 to use variables in ssl_certificate and ssl_certificate_key.
check nginx -V for the following:
```
...
TLS SNI support enabled
```

PSQL

Magic words:

psql -U postgres

Some interesting flags (to see all, use -h or --help depending on your psql version):

-E: will describe the underlaying queries of the \ commands (cool for learning!)
-l: psql will list all databases and then exit (useful if the user you connect with doesn't has a default database, like at AWS RDS)

	# best practice: linux
	nano ~/.pgpass
	:5432::username:password
	chmod 0600 ~/.pgpass

	# best practice: windows
	edit %APPDATA%\postgresql\pgpass.conf
	:5432::username:password

	# linux

	#
	# CORS header support
	#
	# One way to use this is by placing it into a file called "cors_support"
	# under your Nginx configuration directory and placing the following
	# statement inside your location block(s):
	#
	# include cors_support;
	#
	# As of Nginx 1.7.5, add_header supports an "always" parameter which

	{
	"Version": "2012-10-17",
	"Statement": [
	{
	"Action": [
	"logs:*"
	],
	"Effect": "Allow",
	"Resource": "*"
	}

	sudo amazon-linux-extras install epel -y
	sudo yum install stress -y