Easily Secure your Ubuntu server

This guide describes how to secure Ubuntu 14.04 LTS server in only a few minutes with a few simple steps. It may not be the best way for everyone but it works well for me.

What you need to begin.

SSH client (e.g. PuTTY) connected to your Ubuntu server as root.

How to toughen up server access.

Begin by setting a new root password:

passwd

Run any available package upgrades:

apt-get update
apt-get -y upgrade

Install fail2ban to help protect against brute force attacks:

apt-get install -y fail2ban

Setup a new user for server administration. You will need the password that is set here when using sudo with the admin account:

useradd -m -d /home/admin -s /bin/bash admin
passwd admin
mkdir /home/admin/.ssh
chmod 700 /home/admin/.ssh

Put your public key in the authorized_keys file. Keys can be generated with tools such as PuTTYgen.

vim /home/admin/.ssh/authorized_keys

Secure the admin user’s home directory:

chmod 600 /home/admin/.ssh/authorized_keys
chown -R admin:admin /home/admin/.ssh

Add sudo privilege to admin user:

visudo

Add the following line in section # User privilege specification.

admin ALL=(ALL:ALL) ALL

Save and exit.

nano /etc/ssh/sshd_config

Change sshd_config parameters as per below.

Port 22123
PermitRootLogin no

Add the following parameter at the end of the file.

AllowUsers admin

Enable firewall and permit SSH access.

ufw allow 22123
ufw enable

Save and exit.

reload ssh
exit

You can now login with your SSH client on port 22123 using your newly created credentials.