Libnids is an implementation of an E-component of Network Intrusion Detection System. It emulates the IP stack of Linux 2.0.x. The libnids library offers IP defragmentation, TCP stream assembly and TCP port scan detection. Libnids is highly configurable, reliable, and portable.
You can download it from the following link: https://packetstormsecurity.com/files/download/23499/libnids-1.16.tar.gz
Source: https://packetstormsecurity.com/files/23499/libnids-1.16.tar.gz.html