Detecting Network Intrusions: Snort IDS Rules and Configuration

Intrusion Detection Systems (IDS) monitor network packets for known attack signatures and log malicious actions. Snort is a popular open-source network IDS.

1. Snort Rule Structure

Snort rules consist of a header (action, protocol, IPs, ports) and options (payload signatures, metadata):

alert tcp any any -> 192.168.1.0/24 80 (msg:"GET Web Attack"; content:"UNION SELECT"; sid:1000001;)

2. Signature Analysis

• protocol: Filters packet types (tcp, udp, icmp).
• content: Searches for exact string sequences (like SQL payloads) inside packet payloads.

3. Defensive Strategy

Combine Snort rules with firewall scripts to automatically block IP addresses matching critical attack patterns.