Intrusion Detection and Prevention Systems
- Networking Fundamentals & OSI Model
- TCP/IP Model
- Network Topologies
- IP Addressing & Subnetting
- Routing Algorithms & Protocols
- Switching Concepts
- Transport Layer Protocols (TCP & UDP)
- Application Layer Protocols
- Network Security & Firewalls
- Wireless Networking & Wi-Fi
- Network Address Translation (NAT)
- DNS Deep Dive
- Congestion Control & Flow Control
- Error Detection & Correction
- Network Devices
- VPN & Tunneling
- Load Balancing & CDN Networking
- Socket Programming
- Network Troubleshooting Tools
- Physical Layer & Transmission Media
- Data Link Layer & MAC Addressing
- Ethernet Protocol
- ARP (Address Resolution Protocol)
- ICMP Protocol
- Unicast, Multicast, Broadcast and Anycast
- Proxy Servers
- Port Numbers Reference
- Network Performance Metrics
- Quality of Service (QoS)
- Software-Defined Networking (SDN)
- HTTP/2 and HTTP/3 Overview
- 5G and Mobile Networks
- IoT Networking Basics
- VoIP Networking Basics
The Gap a Firewall Leaves Open
A firewall decides whether traffic is allowed based on addresses and ports, but it doesn't examine traffic for actual attack patterns hidden inside otherwise-permitted connections. IDS and IPS systems fill exactly this gap.
IDS: Intrusion Detection System
An IDS monitors network traffic, compares it against known attack signatures or unusual behavior patterns, and raises an alert when something suspicious is found - but it does not block anything itself. It's a passive observer, sitting alongside the traffic flow rather than directly in its path.
IPS: Intrusion Prevention System
An IPS does everything an IDS does, but sits directly in the traffic's path and can actively block or drop malicious traffic the moment it's detected - turning detection into an immediate, automatic response.
IDS: Traffic ---> [monitored copy] ---> alert only, traffic still passes through
IPS: Traffic ---> [inline inspection] ---> blocked if malicious, otherwise passesTwo Common Detection Approaches
| Method | How it works | Trade-off |
|---|---|---|
| Signature-based | Matches traffic against a database of known attack patterns | Very accurate for known threats, blind to brand-new ones |
| Anomaly-based | Flags traffic that deviates from a learned "normal" baseline | Can catch novel attacks, but prone to more false alarms |
Why Both Approaches Still Coexist
An IDS carries no risk of blocking legitimate traffic by mistake, since it only alerts. An IPS actively protects in real time, but a false positive means it could mistakenly block genuine traffic. Many organizations run both: an IPS for well-understood, high-confidence threats, and an IDS layered on top for broader visibility and investigation.