How to Secure Your Linux Server

Running a Linux server comes with responsibility: you need to harden your system to protect your data and prevent unauthorized access. This guide explains how to safeguard your server, defend against hackers, and maintain a strong security posture.

Essential Security Steps

1. Keep Your System Updated

Regular updates patch vulnerabilities and reduce security risks.

Debian/Ubuntu:

sudo apt update && sudo apt upgrade -y

RHEL/CentOS:

sudo dnf update -y

2. Disable Root Login and Create a Separate User

Edit the SSH configuration file:

sudo nano /etc/ssh/sshd_config

Set:

PermitRootLogin no

3. Use SSH Keys Instead of Passwords

Generate an SSH key pair:

ssh-keygen -t rsa -b 4096

Copy it to your server:

ssh-copy-id user@your-server-ip

Firewall & Intrusion Prevention

1. Configure Firewall (UFW on Ubuntu)

sudo ufw allow 2222/tcp

sudo ufw enable

2. Install and Enable Fail2Ban

sudo apt install fail2ban -y

sudo systemctl enable fail2ban –now

Add SSH protection rules:

sudo nano /etc/fail2ban/jail.local

[sshd]

enabled = true

maxretry = 3

bantime = 3600

Detecting and Responding to Threats

last -a

2. Respond to Suspected Compromises

Change passwords and remove unauthorized SSH keys:

passwd root

rm -rf ~/.ssh/authorized_keys

3. Scan for Malware

sudo apt install clamav -y

sudo freshclam

sudo clamscan -r / --remove

For severe breaches, consider reinstalling the server and restoring from a clean backup.

Backup and Disaster Recovery

1. Local Backup Using rsync

rsync -a /var/www/html /backup/

2. Remote Backup Using Contabo S3-Compatible Object Storage

aws s3 cp /backup/ s3://your-bucket-name --recursive

3. Automate Backups with Cron

crontab -e

0 2 * * * rsync -a /var/www/html /backup/

Alternatively, use Contabo’s Auto Backup add-on for fully automated backups.

Watch Our YouTube Video on How to Secure Your Linux Server

If you prefer a visual walk-through, we have a YouTube video on our channel ready for you:

Conclusion

Securing your Linux server involves keeping your system updated, disabling root login, using SSH keys, configuring a firewall, monitoring for threats, and maintaining reliable backups.