A distribution of Nginx with some advanced features
Nagios network monitoring software is enterprise server monitoring
VoIP SIP and SKINNY quality analyzer and packet / audio recording tool
Anti Spam SMTP Gateway
UltraVNC: Remote Access Tools VNC/RFB Remote Desktop Support Software
Xplico is a Network Forensic Analysis Tool (NFAT)
The Internet of Things
a secure, open source OS for use inside USEagency facilities
Tool for identifying Network Service Dependencies
Example for a sercos III Network Driver