show package version history

sudo apt-cache showpkg firefox 01

downgrade a package

apt-get install --reinstall --allow-downgrades <package-name>=<version> -y

lock package version

apt-mark hold <package-name>

Change password

passwd

initial server setup

More often than not I'm starting from the Ubuntu container template (CT) in Proxmox, so the following commands are assuming you're logged in as root. When starting from the Ubuntu ISO, the current user/password will probably be ubuntu. Either add sudo to the following commands or log in as root if that's the case.

Update packages

apt update && apt upgrade

Add new user

adduser <username>

Give new user privs.

usermod -aG sudo <username>

Logout and login as new user. (sudo will be required after this step)

logout

Remove the shell from root

sudo usermod -s /usr/sbin/nologin root

Disable root from logging in

sudo usermod -L root

Remove default ubuntu user (only if using the full Ubuntu ISO)

sudo userdel ubuntu

Set up UFW rules

sudo ufw default deny incoming

sudo ufw enable

Install ZSH

sudo apt install zsh

Set ZSH as default shell and logout/login

sudo chsh -s $(which zsh)

logout

Install Oh My ZSH

sh -c "$(wget https://raw.github.com/ohmyzsh/ohmyzsh/master/tools/install.sh -O -)"

Change ZSH theme (I like cloud the best 🤷‍♀️)

sudo nano ~/.zshrc

Install tmux

sudo apt install tmux