Security Engineering
Jun 12, 2025
12 minute read
Security / Dev
Building a Real-Time NIDS with C++ and libpcap
A deep dive into crafting a high-performance network intrusion detection system from scratch — packet capture, rule engines, and live alerting.
Overview
This post covers the architecture of a real-time NIDS built from scratch in C++ using libpcap...
Packet Capture Layer
#include <pcap.h>
void packet_handler(u_char *user, const struct pcap_pkthdr *h, const u_char *bytes) {
// Parse ethernet, IP, TCP/UDP headers
}
Rule Engine
The rule engine uses a YARA-inspired syntax to match patterns in packet payloads...
Alerting
Alerts are written to a local SQLite database and displayed in a React dashboard via WebSocket.