Question 1

How does Intrufend compare to Suricata for OT/ICS networks?

Accepted Answer

Intrufend supports 68 protocols (36 OT/ICS) vs Suricata's ~25 (~3 OT). It includes passive asset discovery, anomaly baseline learning, and semantic event matching (PLC mode changes, firmware uploads) that Suricata lacks. Detection throughput is 1.8x faster on the same hardware.

Question 2

Is Intrufend faster than Suricata?

Accepted Answer

Yes. On identical hardware (Intel Xeon E3-1225 v5, 4 cores, 8GB RAM) with 49K rules: Intrufend achieves 130K+ PPS single-core detection vs Suricata's ~71K PPS (1.8x faster). Live capture throughput reaches 1.6 Gbps with zero drops. Startup is 8x faster (3.1s vs 25.7s).

Question 3

Can Intrufend use Suricata rules?

Accepted Answer

Yes. Intrufend loads Suricata .rules files natively — same parser, same keywords (content, pcre, flow, flowbits, byte_test, sticky buffers, threshold). All 49,000+ ET-Open community rules work without conversion. Intrufend also supports a native YAML rule format with OT-specific field matching.

Question 4

What OT/ICS protocols does Intrufend support?

Accepted Answer

Intrufend supports 36+ OT/ICS protocols including Modbus TCP/RTU, DNP3, IEC 60870-5-104, S7comm, EtherNet/IP + CIP, OPC UA, IEC 61850 (MMS/GOOSE/SV), BACnet, PROFINET, CODESYS, TriStation, UMAS, DeltaV, FINS, HART-IP, and vendor-specific protocols from ABB, Emerson, GE, Honeywell, Schneider, Siemens, and Yokogawa.

Question 5

Is Intrufend IDS free?

Accepted Answer

Yes, Intrufend offers a free IDS for OT, IoT, and ICS networks. The Community Edition is free for internal use with 10 protocol parsers (HTTP, DNS, TLS, SSH, SMTP, SNMP, NTP, MQTT, Modbus, DNP3), 49K+ community rules, and DPDK support. No registration required. The OEM Edition includes all 68 protocols, redistribution rights, white-label branding, and commercial support.

Question 6

Is there a free IDS for IoT networks?

Accepted Answer

Yes. Intrufend IDS Community Edition is a free intrusion detection system that supports IoT protocols including MQTT, CoAP, AMQP, and HTTP alongside OT/ICS protocols like Modbus and DNP3. It provides deep packet inspection, anomaly detection, and passive asset discovery for IoT networks. Free download at intrufend.org with no registration or traffic limits.

Question 7

What is the best free IDS for OT and ICS networks?

Accepted Answer

Intrufend IDS is purpose-built for OT and ICS networks with 36+ industrial protocol parsers (Modbus, DNP3, IEC 104, S7comm, EtherNet/IP, OPC UA, BACnet, and more). Unlike Suricata and Snort which support only 2-3 OT protocols, Intrufend provides deep protocol inspection, passive asset discovery, anomaly baseline learning, and Tbps-scale throughput. The Community Edition is free for internal use.

	Intrufend	Suricata	Snort 3
Focus	OT/ICS networks	IT networks (some OT)	IT networks
Architecture	Multi-process (crash isolation)	Multi-threaded	Multi-threaded
License	Proprietary (free + OEM)	GPL-2.0	GPL-2.0
Maintained by	Intrufend Project	OISF	Cisco / Talos
Plugin language	Rust (memory-safe)	C + Rust (new parsers)	C++

Metric	Intrufend	Suricata 7.0.3
Detection PPS (single core)	130K+	~71K
Live capture throughput	1.6 Gbps	~215 Mbps
Startup time	3.1s	25.7s
Live capture drops	0%	52.3%
Memory (RSS)	~734 MB	~725 MB

Cores	Intrufend	Suricata	Advantage
1	~2 Mpps	~2 Mpps	Parity
4	~8 Mpps	~6 Mpps	+33%
8	~15 Mpps	~10 Mpps	+50%
16	~28 Mpps	~14 Mpps	+100%
32	~50 Mpps	~18 Mpps	+178%
64	~90 Mpps	~20 Mpps	+350%

Feature	Intrufend	Suricata	Snort 3
Rule format	Suricata-compatible + YAML	Suricata rules	Snort rules
Community rules (ET Open)	Load directly (49K+ rules)	Load directly	Conversion needed
OT-specific rule keywords	40+ fields across all protocols	Limited (modbus, dnp3)	Very limited
Semantic event matching	Yes (write_command, mode_change, program_upload, ...)	No	No
Anomaly baseline learning	Yes (1-30 day configurable)	No	No
Passive asset discovery	Yes (from protocol traffic)	No	No
Device role inference	Yes (PLC, RTU, HMI, SCADA, SIS)	No	No
IT/OT boundary detection	Yes (cross-zone traffic alerting)	No	No
File extraction	11 protocols (HTTP, FTP, SMB, S7Comm, CIP, OPC UA, ...)	HTTP, FTP, SMB, SMTP, NFS	HTTP, FTP
TLS inspection	JA3/JA3S + policy enforcement	JA3/JA3S/JA4	Basic
Flow bypass	Built-in (with periodic re-inspection)	eBPF/XDP (external, Linux-only)	No

Capability	Intrufend	Suricata	Snort 3
Designed for OT	Yes (primary focus)	IT-first, OT bolted on	IT-only
PLC program transfer detection	Yes (S7Comm, CODESYS, TriStation, CIP, DNP3)	No	No
PLC mode change detection	Yes (Run/Program/Stop)	No	No
Write command awareness	Semantic detection (not just byte matching)	Keyword matching only	No
Safety system (SIS) awareness	Yes (Triconex, SIL-rated devices tracked)	No	No
Asset database	Built-in (persisted, pre-seeded from YAML)	No	No
Maintenance window suppression	Yes (scheduled silence windows)	No	No
Serial / RS-485 capture	Native (Modbus RTU framing)	No	No
Vendor-specific protocols	15+ (ABB, Emerson, GE, Honeywell, Schneider, Siemens, Yokogawa)	0	0
Compliance (NERC CIP, IEC 62443)	Asset tracking + baseline auditing	Manual	No

Intrufend vs Suricata vs Snort

Overview

At a Glance

Performance

Detection Throughput

Multi-Core Scaling (DPDK)

Protocol support

OT/ICS Protocols

IT Protocols

Features

Detection & Analysis

OT/ICS-Specific Capabilities

Architecture & Deployment

Output & Integration

Recommendation

When to Choose What

Try it yourself

Protocol	Intrufend	Suricata	Snort 3
Modbus TCP	Full deep inspection	Basic keywords	Via plugin
Modbus RTU (serial)	Native + serial capture	No	No
DNP3	Full stack with CRC	Basic parser	Via plugin
IEC 60870-5-104	Full deep inspection	No	No
S7Comm / S7Comm-Plus	Full deep inspection	No	No
EtherNet/IP + CIP	Full deep inspection	Basic keywords	Via plugin
OPC UA	Full deep inspection	No	No
IEC 61850 (MMS/GOOSE/SV)	Full deep inspection	No	No
PROFINET	Full deep inspection	No	No
BACnet	Full deep inspection	No	No
CODESYS V3	Full deep inspection	No	No
TriStation (Triconex)	Full deep inspection	No	No
UMAS (Schneider)	Full deep inspection	No	No
DeltaV (Emerson)	Full deep inspection	No	No
GE SRTP/EGD	Full deep inspection	No	No
FINS (OMRON)	Full deep inspection	No	No
HART-IP	Full deep inspection	No	No
ABB, Honeywell, Yokogawa, SEL	Full deep inspection	No	No
OT Protocol Count	36+	~3	~2

Protocol	Intrufend	Suricata	Snort 3
HTTP/1.x	Yes	Yes	Yes
TLS (JA3/JA3S)	Yes	Yes (+ JA4)	Basic
SSH (HASSH)	Yes	Yes	Basic
DNS	Yes	Yes	Yes
SMB/SMB2	Yes	Yes	Yes
RDP	Yes	Partial	No
QUIC	Yes	Yes	Basic
MQTT	Yes	Yes	No
CoAP / AMQP / SIP	Yes	No	No
IMAP / POP3 / MS-SQL	Yes	Basic/No	No
Total Protocols	68	~25	~15

Feature	Intrufend	Suricata	Snort 3
Processing model	Multi-process (crash isolation)	Multi-threaded (shared fate)	Multi-threaded (shared fate)
Crash recovery	Auto-respawn crashed workers	Full engine restart required	Full engine restart required
Core scaling	Linear (no contention)	Diminishing returns >16 cores	Diminishing returns >8 cores
DPDK capture	Auto-detected, per-worker queues	Yes (since 7.0)	Yes (via DAQ)
Zero-downtime upgrade	Yes (automatic rollback on failure)	No (restart required)	No
Config hot-reload	SIGHUP (rules, protocols, output, anomaly)	SIGHUP (rules only)	No
Engine binary size	200 KB + loadable plugins	~20 MB (monolithic)	~30 MB (monolithic)
Per-protocol enable/disable	Yes (config-driven)	No	No
Plugin crash isolation	Worker respawn, others unaffected	Engine crash	Engine crash
Platform	FreeBSD + Linux	Linux (primary), FreeBSD	Linux

Feature	Intrufend	Suricata	Snort 3
JSON log (eve.json)	Yes	Yes	Yes
Kafka (native)	Yes (per-topic routing, file streaming)	Via plugin	Via plugin
Syslog (CEF/LEEF)	Yes (UDP/TCP/TLS, multi-server)	Yes	Yes
PCAP dump	Yes (alerting packets with context)	Yes	Yes
REST management API	Yes (34 endpoints)	Unix socket (limited)	No
Management CLI	intrufend-ctl (status, reload, upgrade, rollback)	suricatasc (limited)	No
Self-test	Built-in (--self-test)	No	No