Sure! Here’s a beginner-friendly guide to using Snort, an open-source intrusion detection and prevention system (IDS/IPS). This guide covers installation, configuration, and basic usage.

🛠️ Step 1: Install Snort#

On Ubuntu/Debian:# 

sudo apt update
sudo apt install snort

You’ll be prompted for your network interface (like eth0, ens33, etc.). You can also configure this later in /etc/snort/snort.conf.

On CentOS/RHEL:#

You’ll need to build from source or use a compatible repo. Let me know if you need help with that specifically.

📁 Step 2: Understand the Directory Structure#

After installation, key files are usually found in:

  • Configuration: /etc/snort/
  • Rules: /etc/snort/rules/
  • Log files: /var/log/snort/

⚙️ Step 3: Configure Snort#

Edit the config file:

sudo nano /etc/snort/snort.conf

Key configurations:#

  • HOME_NET: Set to your local IP range (e.g., 192.168.1.0/24)
  • EXTERNAL_NET: Usually set to any
  • RULE_PATH: Make sure it points to your rules directory (e.g., /etc/snort/rules)

Make sure to include a list of rule files at the bottom, like:

include $RULE_PATH/local.rules

📝 Step 4: Add or Edit Rules#

Create or edit your own rules in local.rules:

sudo nano /etc/snort/rules/local.rules

Example rule (alert on ICMP/ping requests):

alert icmp any any -> any any (msg:"ICMP Packet Detected"; sid:1000001; rev:1;)

🚦 Step 5: Run Snort#

Test configuration:# 

snort -T -c /etc/snort/snort.conf

Run in IDS mode:# 

snort -A console -q -c /etc/snort/snort.conf -i eth0

Replace eth0 with your actual network interface.

📊 Step 6: Analyze Logs#

Logs are stored in /var/log/snort/. You can review alerts using tools like:

  • cat /var/log/snort/alert
  • barnyard2 for database output (advanced)

🚧 Optional: Use PulledPork for Rule Management#

PulledPork is a tool to manage Snort rules automatically from Snort.org. You need a Snort Oinkcode to download community or subscription rules.

Would you like a visual network diagram showing where Snort sits in a network or an example use case like monitoring a small home network?