UTMStack

Articles, updated 11 min read

Best HIDS Tools in 2026: Host Intrusion Detection Compared

By UTMStack Team

Attackers who get past the firewall do their work on hosts: they log in, run commands, add accounts, change files and plant ways back in. A host-based intrusion detection system (HIDS) watches for exactly that, from inside each server or laptop. The trouble with most “best HIDS tools” lists is that they are years old. Some tools on them have not shipped a release since 2018, and one has been retired by its owner.

We checked every tool below against its own website or GitHub repository in October 2026: the license, the latest stable release and whether anyone is still maintaining it. We build UTMStack, a SIEM that collects host logs but is not itself a HIDS, so weigh our view accordingly.

The short answer: for most teams in 2026 the best open source HIDS is Wazuh, for its agent’s file integrity, configuration and vulnerability checks with a central dashboard. OSSEC is the lighter choice and is actively developed again, with version 4.4.0 released in October 2026. osquery is best for asking questions of your endpoints, Falco for Linux servers, containers and Kubernetes, and AIDE or Samhain for plain file integrity checking. Tripwire Open Source has not had a release since 2018. A HIDS watches what happens on a host; a network IDS (NIDS) watches traffic between hosts. Most organizations need both, sending their alerts to a SIEM.

HIDS vs NIDS, and where HIPS fits

HIDS (host-based)NIDS (network-based)
Where it runsAn agent on each server or endpointA sensor on a network tap or mirrored switch port
What it seesLogins, processes, commands, file and registry changes, local logsConnections, protocols and traffic content between machines
Blind spotsMachines without an agent; an attacker with full control of a host can tamper with itEncrypted content, traffic that never crosses the sensor, anything inside a host
Open source examplesWazuh, OSSEC, osquery, Falco, AIDE, SamhainSuricata, Snort, Zeek
Prevention versionHIPS: acts on the host, for example blocking an address or stopping a processNIPS: sits inline and drops malicious traffic

A host-based intrusion prevention system (HIPS) is a HIDS that also acts. Wazuh and OSSEC do this through “active response” scripts that can block an address or disable an account, and Fail2ban bans addresses after repeated failed logins. Automatic blocking on the host is powerful and easy to get wrong, so start in alert-only mode and add actions one rule at a time. For the wider picture, see our guide to intrusion detection systems.

Which HIDS tools are still maintained?

Latest stable release, checked on each project's own site or GitHub in October 2026

Released in 2026Actively maintained
  • OSSEC 4.4.0: Oct 2026
  • Wazuh 4.14.8: Sep 2026
  • Falco 0.45.0: Sep 2026
  • Security Onion 3.3.0: Sep 2026
  • Sysmon: Sep 2026
  • AIDE 0.19.4: Aug 2026
  • Fail2ban 1.1.1: Aug 2026
  • Linux audit 4.2.1: Jul 2026
  • osquery 5.23.1: Jun 2026
Slow, steady releasesMaintained
  • Samhain 4.5.3: Oct 2025
No release since 2018Dormant
  • Tripwire Open Source 2.4.3.7: Mar 2018
Withdrawn by its ownerRetired
  • AlienVault OSSIM
Release dates are for the latest stable version. Wazuh 5.0 was in release-candidate testing in October 2026.

The best HIDS tools in 2026

1. Wazuh

Wazuh began as a fork of OSSEC and grew into a full platform: an agent on each host, a manager that decodes and correlates events, and an indexer and dashboard for search. The agent covers file integrity monitoring, configuration assessment against CIS benchmarks, vulnerability detection, malware detection, log analysis and active response, on Windows, Linux, macOS and several Unix systems.

  • Strengths: the broadest open source HIDS feature set, a large community and compliance mappings an auditor can follow.
  • Limits: the indexer needs memory and fast disks as data grows, and it takes tuning to keep alerts manageable.
  • License and status: GPLv2. Actively maintained; 4.14.8 shipped in September 2026 and version 5.0 is in release-candidate testing.

2. OSSEC

OSSEC is the original open source HIDS, and the project is busy again. Atomicorp manages it and released OSSEC 4.0 in February 2026, then four more versions through 4.4.0 on October 5, 2026. It analyzes logs, checks file integrity, detects malware and runs active response, on Windows, Linux, macOS, the BSDs and other Unix systems.

  • Strengths: a small footprint, simple architecture and a long track record. Recent releases added Windows file attribute and permission checks and JSON alerts over syslog.
  • Limits: it has no built-in dashboard for searching history, so pair it with a SIEM or log store. Atomicorp sells a commercial edition, Atomic OSSEC, with extra platforms and features.
  • License and status: GPLv2. Actively maintained.

3. osquery

osquery turns the operating system into a database you query with SQL: running processes, listening ports, logged-in users, installed software, startup items and much more, on Linux, macOS and Windows. Scheduled queries can report changes over time, which makes it a strong detection and hunting source.

  • Strengths: flexible, precise questions across a whole fleet, such as “which machines have this browser extension?”
  • Limits: it is an instrument, not an alerting system. You need a fleet manager to distribute queries and a SIEM to store results and raise alerts.
  • License and status: dual Apache 2.0 or GPLv2. Actively maintained; 5.23.1 is the latest stable release, with 5.24.0 in pre-release in October 2026.

4. Falco

Falco watches Linux kernel events, using eBPF, and checks them against rules in real time. It understands containers and Kubernetes, so a shell spawned inside a production container or a sensitive file read by an unexpected process becomes an alert with the pod and image attached. Plugins extend it to sources such as AWS CloudTrail and Okta.

  • Strengths: the best fit on this list for Linux servers and container platforms, and a graduated project of the Cloud Native Computing Foundation (CNCF).
  • Limits: Linux only, and its rules need tuning for each workload.
  • License and status: Apache 2.0. Actively maintained; 0.45.0 shipped in September 2026.

5. AIDE

AIDE, the Advanced Intrusion Detection Environment, does one job: it records a baseline of files and directories (hashes, permissions, owners) and reports anything that changes. It was written as a free alternative to Tripwire.

  • Strengths: simple, light and auditable. A good way to show an assessor that critical system files are checked for unauthorized change.
  • Limits: no central console and no real-time alerts; it runs on a schedule, and you collect its reports yourself.
  • License and status: GPLv2. Actively maintained; 0.19.4 shipped in August 2026.

6. Samhain

Samhain combines file integrity checking with log monitoring, rootkit detection, hidden process detection, port monitoring and checks for rogue SUID programs. A client and server design stores baselines and configuration centrally, and the Beltane web console handles monitoring.

  • Strengths: centrally managed integrity checking, with more kinds of checks than AIDE.
  • Limits: a small community and a dated interface. Setup takes time.
  • License and status: GPL. Maintained with a slow release pace; 4.5.3 shipped on October 31, 2025.

7. Security Onion

Security Onion is a free platform for network security monitoring, built on Suricata, Zeek and Elastic; version 3.0 shipped in March 2026. Its host visibility comes from the Elastic Agent, with live queries through osquery and central management through Elastic Fleet. It is network-first, with host data alongside.

  • Strengths: network and host data in one console, with alerts, hunting and cases.
  • Limits: heavy hardware needs and a steep learning curve. Version 2.4 reached end of life on October 1, 2026, so plan the move to version 3.
  • License and status: Elastic License 2.0, which is source-available and forbids offering it to others as a hosted or managed service. Actively maintained; 3.3.0 shipped in September 2026.

8. Sysmon and the Linux audit system

These are not HIDS products, but they produce the host events that make a HIDS or SIEM useful. Sysmon, free from Microsoft Sysinternals, logs process creation with full command lines, network connections, driver loads, file creation and much more to the Windows event log. Microsoft is clear that it does not analyze those events itself. The Linux audit system (auditd) records system calls, commands and file access according to rules you set.

  • Strengths: deep, free host telemetry from sources most security tools already understand.
  • Limits: nothing raises an alert until another tool reads the events. Both need careful configuration to avoid drowning you in data.
  • License and status: Sysmon for Windows is free but closed source; Sysmon for Linux is MIT licensed. The Linux audit userspace tools are GPLv2. All are actively maintained.

9. Fail2ban

Fail2ban reads log files and bans addresses that cause repeated authentication failures, by adding firewall rules. It is the simplest host-based prevention tool on the list, and a sensible default on any Linux server that exposes SSH or a web login.

  • Strengths: tiny, easy to understand and effective against password guessing.
  • Limits: it only handles patterns it can see in logs, and a careless rule can lock out legitimate users.
  • License and status: GPLv2. Actively maintained; 1.1.1 shipped in August 2026.

What happened to Tripwire and AlienVault?

Tripwire Open Source still works, but its last release was 2.4.3.7 in March 2018 and its code has barely changed since. Choose AIDE or Samhain for new deployments. The commercial product, Fortra’s Tripwire Enterprise, is a separate, maintained product for file integrity and configuration management.

AlienVault OSSIM, which appears on many older lists, is no longer offered. LevelBlue, which now owns the AlienVault products, says on its own site that OSSIM is no longer in use.

Comparison at a glance

ToolMain jobPlatformsLicenseLatest stable (Oct 2026)Maintained
WazuhFull HIDS with central dashboardWindows, Linux, macOS, UnixGPLv24.14.8, Sep 2026Yes
OSSECLightweight HIDSWindows, Linux, macOS, BSD, UnixGPLv24.4.0, Oct 2026Yes
osqueryEndpoint queries and telemetryWindows, Linux, macOSApache 2.0 or GPLv25.23.1, Jun 2026Yes
FalcoRuntime detection for Linux and containersLinuxApache 2.00.45.0, Sep 2026Yes
AIDEFile integrity checkingLinux, UnixGPLv20.19.4, Aug 2026Yes
SamhainFile integrity, rootkit and log checksLinux, UnixGPL4.5.3, Oct 2025Yes, slowly
Security OnionNetwork monitoring with host dataServer: Oracle Linux 9Elastic License 2.03.3.0, Sep 2026Yes
Fail2banBan addresses after failed loginsLinux, UnixGPLv21.1.1, Aug 2026Yes
Tripwire Open SourceFile integrity checkingLinux, UnixGPLv22.4.3.7, Mar 2018No

How to choose a HIDS

Which HIDS fits?

Start with what you need to watch

What is the first job?
Watch a fleet of servers and laptops
WazuhFull features and a dashboard
OSSECLighter, alerts only
osqueryQuestions and telemetry
Something narrower
FalcoContainers and Kubernetes
AIDE or SamhainFile integrity for audits
Fail2banStop password guessing
Whichever you pick, send its alerts to a SIEM, where they can be kept, searched and correlated with network and cloud logs.
  1. List what you must watch: Windows, Linux, macOS, containers or legacy Unix. That alone narrows the list.
  2. Decide whether you need file integrity checking. PCI DSS and several other frameworks ask for change detection on critical files; Wazuh, OSSEC, AIDE and Samhain do it.
  3. Count the people you have. A HIDS raises alerts that someone has to read and tune. A lighter tool that is well tuned beats a full platform nobody looks at.
  4. Plan where alerts go. A HIDS on its own sees one host at a time. A SIEM connects a failed login on a server with the VPN session and the firewall traffic around it.
  5. Pilot on a handful of hosts for two weeks, tune, then roll out.

Where UTMStack fits

UTMStack is a SIEM, not a HIDS in the classic sense: it does not keep file hashes or a file baseline, so pair it with Wazuh, OSSEC, AIDE or Samhain if you need file integrity checking. What it does on hosts:

  • Agents for Windows and Linux in the free Community edition (the macOS agent is paid) collect security and system logs, including Sysmon events when Sysmon is installed. The Linux agent sets up the Linux audit system automatically, with rules for commands, privilege changes and access to sensitive files.
  • More than 600 detection rules mapped to MITRE ATT&CK check each event as it arrives, so host events are correlated with firewall, cloud and Microsoft 365 logs.
  • Syslog input, so tools such as OSSEC and Wazuh can forward their alerts into the same place.
  • Response flows can block an address, disable an account or isolate a host through the agent.
  • Vulnerability scans and software inventory run through the agent on Windows and Linux.

Try the live demo with no sign-up, or install the free edition. For the file-change side of host monitoring, see our guide to file integrity monitoring, and for more free tools, our comparison of open source SIEM tools.

Frequently asked questions

What is a HIDS? A host-based intrusion detection system: software on a server or endpoint that watches logins, processes, files and logs on that machine and raises an alert when it sees signs of an attack.

What is the difference between HIDS and NIDS? A HIDS runs on each host and sees what happens inside it. A NIDS watches network traffic between hosts. A HIDS sees commands and file changes that never cross the network; a NIDS sees machines that have no agent. They complement each other.

What is the best free HIDS? For most teams, Wazuh. Choose OSSEC for a lighter agent, Falco for containers and Kubernetes, and AIDE or Samhain if you only need file integrity checking.

Is OSSEC still maintained? Yes. Atomicorp manages the project; OSSEC 4.0 shipped in February 2026 and 4.4.0 in October 2026.

Is Tripwire Open Source still maintained? Not in practice. Its last release was in March 2018. Fortra’s commercial Tripwire Enterprise is a separate, maintained product.

Is Security Onion a HIDS? Not mainly. It is a network security monitoring platform that also collects host data through the Elastic Agent, with osquery for live queries.

Sources

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