Suricata is an Intrusion Detection and Prevention (IDS/IPS) engine developed by the Open Information Security Foundation and its supporting vendors. The engine is multi-threaded and has native IPv6 support, file extraction capabilities, and many more features. It's capable of loading existing Snort rules and signatures, and supports many frontends through Barnyard2.
RackTables is a tool to manage tens of racks, hundreds of servers, and thousands of MAC and IP addresses. It will work with a single rack as well. It features a real-life rackspace model, typed rack objects with flexible attribute sets, a tagging system, IP address management ready for NAT, virtual routers and load balancers, accurate network connection handling, a universal search function, a multi-user access model, and an extensible dictionary.
MasarLabs PatD is a daemon to ping or traceroute remote hosts, using IPv4 or IPv6 ICMP packets. It runs without root privileges, listening on a TCP local port for hosts to check. It uses a protocol simple to implement, so is useful in situations in which you cannot send native ICMP packets (for example, from a Java program). pat is a client you can use to talk to patd.
Astaro Security Gateway (formerly Astaro Security Linux) is an all-in-one network security gateway that includes a firewall, intrusion protection, antivirus, spam protection, URL filtering, and a VPN gateway. Features include a modern packet filter, intrusion detection and prevention, portscan detection, application control, content filtering, virus detection for email and Web traffic, profile handling, L2TP, IPSec, SSL, and PPTP VPN tunneling, spam blocking, proxies for HTTPS, HTTP, FTP, POP3, SMTP, DNS, VoIP, SOCKS, and Ident, logging, and reporting. It supports Ethernet, VLAN, PPP, PPPoE, PPPoA, Cable Modem, IPv6, QoS, Link Aggregation, and WAN-Uplink-Load balancing in routing, and bridge mode. The WebAdmin GUI, Install Wizard, Change Tracking, Printable Configuration, and Up2Date service make it easy to install, manage, and maintain.
ip2clue provides access to multiple databases (Maxmind, Software 77, Webhosting.info and ip2location) to retrieve country information associated with IP addresses. It has a daemon that supports lots of concurrent connections and a client binary. Some client examples are also provided in languages including PHP and C.
conexus is a generalized C++ I/O library that includes network support for IPv4 and IPv6 sockets, serial/TTY communications, kernel message queues, pipes, and files. Objects use sigc++ for signaling property changes and other information. Sub-libraries include conexus-gtkmm (provides a set of gtkmm widgets), conexus-dbus (provides dbus support for endpoints), conexus-nspr (provides NSPR endpoints), conexus-nss (provides NSS endpoints), and conexus-ssl (provides OpenSSL endpoints).