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Before you start the hardening process, there are several important tasks you need to complete to ensure your server is properly configured.

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Pre-Installation Requirements

1

Disable Port Forwarding

If you’re opening ports on your router so you can access your server from the outside, disable the port forwarding until your system is up and secured.
Never expose an unsecured server to the internet. Complete all hardening steps before enabling external access.

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Post-Installation Requirements

1

Verify SSH Access

Unless you’re doing everything physically connected to your server, you’ll need remote access so be sure SSH works.Test SSH connectivity before proceeding:
ssh user@server-ip
2

Keep System Updated

Keep your system up-to-date with the latest patches.For Debian-based systems:
sudo apt update && sudo apt upgrade
For RHEL-based systems:
sudo dnf update
3

Perform System-Specific Tasks

Make sure you perform any tasks specific to your setup:
  • Configuring network - Set static IP if needed
  • Configuring mount points in /etc/fstab
  • Creating the initial user accounts
  • Installing core software you’ll want like man
  • Any other environment-specific configurations
4

Configure Email Alerts

Your server will need to be able to send e-mails so you can get important security alerts.
If you’re not setting up a full mail server, you can configure a simple MTA (Mail Transfer Agent) to relay through Gmail or another service. Check the guide’s section on Gmail and Exim4 configuration.
5

Review CIS Benchmarks

I would also recommend you read through the CIS Benchmarks before you start with this guide.

CIS Benchmarks

The Center for Internet Security (CIS) provides comprehensive, industry-trusted benchmarks for securing Linux systems.Recommendation: Go through this guide first and THEN CIS’s guide. That way their recommendations will trump anything in this guide.

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Other Important Notes

Critical Reminders:
  • This guide is written and tested on Debian. Most things should work on other distributions, but package management commands will differ.
  • File paths and settings may differ slightly between distributions - check your distribution’s documentation if you have issues.
  • Read the whole guide before you start. Your use-case and/or principles may call for not doing something or for changing the order.
  • Do not blindly copy-and-paste without understanding what you’re pasting. Some commands will need to be modified for your needs before they’ll work - usernames for example.

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Distribution-Specific Notes

# Package management
sudo apt update
sudo apt install package-name

# Service management
sudo systemctl restart service-name

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Next Steps

Once you’ve completed all these requirements, you’re ready to begin the actual hardening process. The next section will cover securing SSH access to your server.

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