Debian Server Setup

This section assumes you have a fresh Debian 11 install on a server (either physical or VPS)

It will cover installing the essentials for access, and basic security so you don't need to worry in the future. This section may seem a little daunting for a first-time linux user, but most of it is copy/paste, hopefully with enough description to understand what is being done. Just remember not to copy the $/root$ they're there to show what user/directory we're in.

This first section will be done on the physical PC, or on the VPS via their website, or SSH'd as root if that's the option given.

Update the OS

Even with a fresh install of Debian from the latest ISO, there may be some updates you're missing, and it's a good idea to have these, especially in case they're security updates.

> 
					
						root$ apt update && apt upgrade

Install essential packages

These are packages that are needed for accessing, and controlling the server

					
						root$ apt install sudo ssh

Some useful packages too

					
						root$ apt install vim htop wget curl tmux

Add a user, and give super user privilleges

You want to avoid using root as much as possible in regular use, so a new user for yourself is a must

					
						root$ adduser 	
						root$ usermod -aG sudo

*replace with the user you want to create, e.g. nathan

(Local server) Set static IP

If the server is a physical PC in your home you will need to set a static IP, otherwise your router could assign a differnent IP on reboot, and this would mess with port forwarding, and internal DNS.

Secure ssh

Although this is optional, I recommend it, as SSH (secure shell) will be the primary means of access to the server.

					
						root$ vim /etc/ssh/sshd_config

Within the editor you will need to search for PermitRootLogin and set it to no, this prevents ssh as root

Search for Port and set it to a different port to 22, a port over 1024 prevents basic nmap scans, and therefor a lot of bruteforcing, so let's go with 2020 so it's easy to remember

Below the Port line, add a new line with Protocol 2 this enables ssh2, which is more secure

(Optional) Comment/Add a # to the beginning of the passwordlogin line. This will prevent sshing to the server from any PC that doesn't have it's SSH key on the server already. I recommend only doing this if your sshkeys are on the server, or you're comfortable adding them.

					
						root$ systemctl reload sshd

This reloads the ssh daemon, and enables all the changes we've made

Setup UFW

UFW (Uncomplicated Firewall) is a simple to use firewall, that can be used to easily open/close ports on your server.

We'll install ufw, deny access inwards to all ports, but allow our server to access any ports outwards. We will then manually allow inwards traffic to the SSH port we set, in this case 2020

					
						root$ apt install ufw
						root$ ufw deny incoming
						root$ ufw allow outgoing
						root$ ufw allow 2020
						root$ ufw enable

If there are any other ports that need to be opened in the future this can be done with:

					
						root$ ufw allow 
					
					or
					
						root$ sudo ufw allow

Set hostname

Setting the name for a server is an important step, but the name doesn't need to be serious

					
						root$ vim /etc/hosts
						root$ vim /etc/hostname

Within both of these files the hostname should be changed to the same thing

This next section can be done via a terminal, or an SSH client e.g. PuTTY for Windowss. For the sake of the guide, this assume you're using a Unix terminal

Create an SSH key

We'll create an ed25519 ssh-key, as it's more secure, and performant than the defaultrsa

					
						$ ssh-keygen -t ed25519

SSH into the server

This is a two part section, and I recommend using this every time you SSH into a server from a new PC

					
						$ ssh @ -p 2020

This will likely display a message asking to verify the key for the server. This is to prevent man-in-the-middle attacks, so I reccommend verifying this whenever asked.

To check the key for the server, you need to run this command on the server.

					
						$ ssh-keygen -l -f /etc/ssh/ssh_host__key.pub

Replace with the key the message is asking about. Then if key the server shows matches that on your PC you are SSHing from, type yes and hit enter

TODO:(Optional) Fail2Ban

TODO:(Optional) Unattended Upgrades

Updates to a server typically want to be done by a human in case things go wrong, but smaller updates can be set to be done automatically

TODO:(Optional) Setup User preferences

These are a few things I personally like to have on a basic server

Vi mode bash

Aliases

Ctrl-L clear-screen

BashRC PS1

Server maintance notes

Keep the server up-to date as much as possible

Only install things that you need. If this is a server for learning, half ignore this, but for production servers only install services, and make changes that are required.