Setting up Uncomplicated FireWall (UFW)

Primarily used on Ubuntu and Debian:

apt-get install ufw
 
ufw enable
 
ufw default deny incoming
ufw default allow outgoing
 
# checkit:
ufw status verbose
 
# add ssh
ufw allow ssh
 
# add other rules by servicename or custom, e.g. for Redis:
# ufw allow in on eth1 to any port 6379 proto tcp

see more here

Apt-get update cheatsheet for Ubuntu/Debian

sudo apt-get update        # Fetches the list of available packages and updates
sudo apt-get upgrade       # Strictly upgrades the current packages
sudo apt-get dist-upgrade  # Installs updates (new ones)
 
sudo apt-get install {package-name}  # install
sudo apt-cache search {package-name} # search

Debian ‘ps’ command from Apt

A lot of minimal Debian distros don’t have the `ps` process status app by default. There are times it’s useful when you want to inspect a container from the inside, so add:

`apt-get install -y procps`

to your build or manually install it after. Adds about 1MB to your environment.