How Plesk Works with ModSecurity, Fail2Ban, and Imunify360 Security Tools

Table of Contents

• Overview
• Compatibility Matrix
• Recommended Setups
• ModSecurity + Fail2Ban Setup
• Imunify360 Setup
• Troubleshooting
• Best Practices

Overview

Important Notice

These security tools are not designed to work simultaneously. You must choose ONE of the following configurations:

• ModSecurity + Fail2Ban
• Imunify360 (standalone)

Compatibility Matrix

Prerequisites

• Plesk Obsidian or later
• Apache 2.4.x or newer
• Root access to your server
• Linux (CentOS 7+, Ubuntu 20.04+, or Debian 11+)

Recommended Setups

Option 1: ModSecurity + Fail2Ban

Best for:

• Standard hosting environments
• Budget-conscious deployments
• Customizable security rules

Option 2: Imunify360

Best for:

• Enterprise hosting environments
• Managed hosting providers
• High-security requirements

ModSecurity + Fail2Ban Setup

1. Enable ModSecurity in Plesk

Verify ModSecurity installation

sudo plesk sbin modsecurity_ctl -s

Enable ModSecurity

sudo plesk sbin modsecurity_ctl --enable

2. Configure Fail2Ban Integration

View current jail settings

sudo fail2ban-client get plesk-modsecurity

Configure jail

sudo vim /etc/fail2ban/jail.d/plesk-modsecurity.conf

# Example configuration:

[plesk-modsecurity] enabled = true filter = plesk-modsecurity logpath = /var/log/modsec_audit.log findtime = 600 bantime = 600 maxretry = 5

Imunify360 Setup

1. Pre-Installation Steps

Disable Fail2Ban if installed

plesk bin fail2ban --disable

Remove existing ModSecurity rules

sudo plesk sbin modsecurity_ctl --disable-all-rules

2. Install Imunify360

Download installer

wget https://repo.imunify360.cloudlinux.com/defence360/i360deploy.sh

Run installer

bash i360deploy.sh --key YOUR_LICENSE_KEY

3. Verify Installation

Check the Imunify360 ModSecurity ruleset

sudo plesk sbin modsecurity_ctl -L --enabled

# Expected output:
custom

Troubleshooting Guide

ModSecurity + Fail2Ban Issues

Check ModSecurity logs

sudo tail -f /var/log/modsec_audit.log

Check Fail2Ban status

sudo fail2ban-client status plesk-modsecurity

View banned IPs

sudo fail2ban-client get plesk-modsecurity banip

Imunify360 Issues

Check Imunify360 status

imunify360-agent status

View Imunify360 logs

tail -f /var/log/imunify360/error.log

Check ModSecurity rules

sudo plesk sbin modsecurity_ctl -L

Best Practices

General Security Guidelines

• Always backup before making security changes
• Test in staging environment first
• Monitor false positives regularly
• Keep all security tools updated

ModSecurity + Fail2Ban

• Start with conservative ban times
• Whitelist trusted IPs
• Regular log review

Imunify360

• Use only Imunify360 ruleset
• Configure automatic updates
• Enable real-time scanning

Common Gotchas to Avoid

• Never run multiple WAF solutions simultaneously
• Don't mix Imunify360 with other ModSecurity rulesets
• Avoid running Fail2Ban with Imunify360
• Don't forget to whitelist legitimate traffic

Monitoring and Maintenance

Regular health checks

For ModSecurity + Fail2Ban:

sudo fail2ban-client status
sudo plesk sbin modsecurity_ctl -s

For Imunify360:

imunify360-agent status
imunify360-agent checkdb | check-domains| check modsec directives | etc