OSSEC-PCI
PCI Security Standards Council is an open global forum for the ongoing development, enhancement, storage, dissemination and implementation of security standards for account data protection. As a part of this initiative the council has published a set of standards, called the Payment Card Industry Data Security Standard (PCI DSS). These standards apply to all payment card network members, merchants and service providers that store, process or transmit cardholder data, and affect all payment channels, including retail (brick and mortar), mail/telephone order and ecommerce.
OSSEC is a scalable, multi-platform, open source Host-based Intrusion Detection System (HIDS)
OSSEC has a powerful correlation and analysis engine, integrating log analysis, file integrity monitoring, Windows registry monitoring, centralized policy enforcement, rootkit detection, real-time alerting and active response. It runs on most operating systems, including Linux, OpenBSD, FreeBSD, MacOS, Solaris and Windows.