FIM vs OSSEC

FIM is free, open-source software for monitoring file systems on premises. It watches files in the background, keeps historical information, emits events when changes occur, creates hashes, and analyzes content, attributes, ownership, and permissions. On Linux, the Audit daemon can identify who caused an event and which command produced it. Events may be written locally, sent over a network, or sent to both destinations. Documentation lists Elasticsearch 8.x or OpenSearch 2.x and Splunk indexer 9.x integrations, with only one integration active at a time. FIM runs on Linux, Windows, and macOS. Installation guidance lists Ubuntu Xenial or later, CentOS 7 or later, Windows 7 or Server 2016 or later, and macOS Big Sur or later. Minimum requirements are one CPU core, 128 MB memory, and 1 GB storage, with storage use increasing over time. The maker says support is free and provides an email contact.

OSSEC is an open-source host-based intrusion detection system for monitoring systems and network components. It analyzes logs, checks file integrity, monitors the Windows registry, detects rootkits, and can alert users in real time or take active response actions. Monitoring can be agent-based or agentless, and a centralized server applies policies across operating systems, with server-specific overrides. Alerts can use SMTP, SMS, and syslog; active response can block an attack immediately. The system runs on Linux, OpenBSD, FreeBSD, macOS, Solaris, and Windows, and supports self-hosted and cloud environments. OSSEC and OSSEC+ use command-line management; Atomic OSSEC editions add a management console and integrations with cloud services and other tools. OSSEC+ adds machine learning, ELK integration, threat sharing, and additional rules. Free OSSEC is listed at free; OSSEC+ is also free, with registration required. Atomic OSSEC is $5 a month per device. Atomic OSSEC SaaS offers a free 14-day trial for up to 10 endpoints.