Host Configuration Security: Protecting Your Network

TL;DR

Yes! You can enforce security settings on computers (hosts) to protect the rest of your network. This guide shows you how, covering Group Policy (Windows), configuration management tools, and basic hardening steps.

1. Understand Host-Based Security

Each computer on your network is a potential entry point for cyber security threats. Enforcing consistent configurations across all hosts reduces the attack surface and makes it harder for attackers to exploit weaknesses. This means setting things like strong passwords, keeping software updated, and disabling unnecessary services.

2. Windows Group Policy (For Domain-Joined Computers)

If your computers are joined to a domain, Group Policy is the easiest way to manage settings centrally. It lets you push out configurations automatically.

1. Open Group Policy Management: Search for ‘Group Policy Management’ in Windows and open it.
2. Edit an Existing Policy or Create New: Right-click on the Organisational Unit (OU) containing your computers, and select ‘Create a GPO in this domain, and Link it here…’ or edit an existing policy.
3. Configure Security Settings: Expand ‘Computer Configuration’, then ‘Windows Settings’, then ‘Security Settings’. Here are some key areas:
   • Account Policies: Set password complexity requirements (minimum length, age, history).
   • Local Policies: Configure audit policies to log important events.
   • Firewall with Advanced Security: Enable the Windows Firewall and configure rules to allow only necessary traffic.
4. Software Restriction Policies (SRP) or AppLocker: Control which applications can run. AppLocker is more modern and flexible.

   gpupdate /force

   (Run this command on a computer to force the policy to update.)

5. Regularly Review Logs: Check the Event Viewer for any errors or suspicious activity related to Group Policy application.

3. Configuration Management Tools (For Mixed Environments)

If you have a mix of Windows, macOS and Linux computers, configuration management tools are essential.

• Ansible: A popular open-source tool that uses SSH to configure hosts. You write ‘playbooks’ in YAML format.

  ansible all -m ping

  (This checks if Ansible can connect to your computers.)

• Puppet: Another powerful configuration management system, using a declarative language.
• Chef: Similar to Puppet, focusing on infrastructure as code.
• Microsoft Intune/Endpoint Manager: Good for managing Windows and mobile devices in the cloud.

These tools let you automate tasks like installing updates, configuring firewalls, and enforcing security policies.

4. Basic Host Hardening Steps (All Operating Systems)

1. Keep Software Updated: Enable automatic updates for the operating system and all applications.
2. Disable Unnecessary Services: Turn off any services that aren’t required. Use a tool like systemctl on Linux to manage services.

   sudo systemctl disable 

3. Strong Passwords & Multi-Factor Authentication (MFA): Enforce strong passwords and enable MFA wherever possible.
4. Firewall: Enable a firewall on each host and configure it to block incoming connections except for those that are absolutely necessary.
5. Antivirus/Anti-Malware: Install and keep antivirus software up to date.
6. Regular Backups: Regularly back up your computers so you can restore them in case of a cyber security incident.

5. Monitoring & Alerting

Don’t just configure – monitor! Use tools like:

• Security Information and Event Management (SIEM) systems: Collect logs from all your hosts and alert you to suspicious activity.
• Host Intrusion Detection Systems (HIDS): Monitor files, processes, and network connections for malicious behaviour.