1. SogoSOGo is a very fast and scalable modern collaboration suite (groupware). It offers calendaring, address book management, and a full-featured Webmail client along with resource sharing and permission handling. It also makes use of documented standards (IMAP, CalDAV, CardDAV, etc.) and thereby provides native connectivity (without plugins) to many clients such as Microsoft Outlook, Apple iCal, the iPhone, Mozilla Lightning, and a plethora of mobile devices.
2. PacketfencePacketFence is a fully supported, trusted, Free and Open Source network access control (NAC) solution. Boasting an impressive feature set including a captive-portal for registration and remediation, centralized wired and wireless management, powerful BYOD management options, 802.1X support, layer-2 isolation of problematic devices; PacketFence can be used to effectively secure networks small to very large heterogeneous networks.
4. dhcp0fPassive DHCP analyzer with OS fingerprinting on the LAN through DHCP