GreenSQL is an Open Source database firewall used to protect databases from SQL injection attacks. GreenSQL works as a proxy and has built in support for MySQL. The logic is based on evaluation of SQL commands using a risk scoring matrix as well as blocking known db administrative commands (DROP, CREATE, etc).

http://www.greensql.net/

Zenoss Core is an open-source network monitoring and server monitoring product.  Zenoss features include

• Network, Server, and Application monitoring with a single product
• Ability to monitor any SNMP enabled device
• Real-time alerting when outages or slowdowns occur
• Single Event Console containing Zenoss alerts, SNMP traps, and log events

http://www.zenoss.com/product/network-monitoring

PacketFence is a free and open source network access control (NAC) system.  The standard feature list illustrated on the official website:

• Registration
  PacketFence supports an optional registration mechanism similar to “captive portal” solutions. An Acceptable Use Policy can be specified such that users cannot enable network access without first accepting it. The duration of a node registration can be a relative value (eg. “four weeks from first network access”) or an absolute date (eg. “Thu Jan 20 20:00:00 EST 2009″).
• Detection of abnormal network activities
  Abnormal network activities (computer virus, worms, spyware, etc.) can be detected using local and remote Snort  sensors. Beyond simple detection, PacketFence layers its own alerting and suppression mechanism on each alert type. A set of configurable actions for each violation is available to administrators.
• Proactive vulnerability scans
  Nessus vulnerability scans can be performed on a scheduled or ad-hoc basis. PacketFence correlates the Nessus vulnerability ID’s of each scan to the violation configuration, returning content specific web pages about which vulnerability the host may have.
• Isolation of problematic devices
  PacketFence supports several isolation techniques, including VLAN isolation with VoIP support (even in heterogeneous environments) for multiple switch vendors.
• Remediation through a captive portal
  Once trapped, all HTTP, IMAP and POP sessions are terminated by the PacketFence system. Based on the nodes current status (unregistered, open violation, etc), the user is redirected to the appropriate URL. In the case of a violation, the user will be presented with removal instructions for the particular infection he/she has.
• 802.1X
  802.1X is supported through a FreeRADIUS module.
• Wireless integration
  PacketFence intregrates perfectly with wireless networks through a FreeRADIUS module. This allows you to secure your wired and wireless networks the same way.
• DHCP fingerprinting
  DHCP fingerprinting can be used to automatically register specific device types (eg. VoIP phones) and to disallow network access to other device types (eg. game consoles).

http://www.packetfence.org

FreeNAS is an embedded open source NAS (Network-Attached Storage) distribution based on FreeBSD, supporting the following protocols: CIFS (samba), FTP, NFS, TFTP, AFP, RSYNC, Unison, iSCSI (initiator and target) and UPnP.  FreeNAS supports additional services such as a Bittorent client, UPnP server, iTunes/DAAP server, and network bandwitdh measurement.  Take a look at the complete featurelist on the official website.

http://www.freenas.org/

Free Windows utility that automatically disaplyes your wireless network interface when your computer is connected via a cable network connection:

http://www.wlanbook.com/disable-wireless-connected-lan-xp-vista/

OpenNebula is an open and flexible tool that fits into existing data center environments to build any type of Cloud deployment. OpenNebula can be primarily used as a virtualization tool to manage your virtual infrastructure in the data-center or cluster, which is usually referred as Private Cloud. OpenNebula supports Hybrid Cloud to combine local infrastructure with public cloud-based infrastructure, enabling highly scalable hosting environments. OpenNebula also supports Public Clouds by providing Cloud interfaces to expose its functionality for virtual machine, storage and network management.

http://www.opennebula.org/

Below I grouped a few links to networking and security related cheat sheets which I find usefull from time to time to use as a reference:

TCP/IP and tcpdump Cheat Sheet – SANS.org

Google Hacking and Defense Cheat Sheet – SANS.org

Intrusion Discovery Cheat Sheet Windows – SANS.org

Intrusion Discovery Cheat Sheet Linux – SANS.org

SQL Injection Cheat Sheet - ha.ckers.org

Cross Site Scripting Cheat Sheet – ha.ckers.org

Web application Cheat Sheet – secguru.com

Linux Security Quick Reference Guide – Linuxsecurity.com

LINUX Administrator’s Quick Reference Card – cheat-sheets.org

Oracle Security Cheat Sheet – red-database-security.com

Nmap & Nessus Cheat Sheet – secguru.com

update: Here are some additional ones:

Security Incident Survey Cheat Sheet – zeltser.com

Initial Security Incident Questionnaire for Responder - zeltser.com

BGP, EIGRP, First Hop Redundancy, 802.1X, IPsec, IPv4 Multicast, IPv6, IS-IS, OSPF , STP, tcpdump, Wireshark, Common Ports, IP Access Lists, Subnetting, Markdown, MediaWiki, MPLS,
QoS, VLANs, Cisco IOS, Physical Terminations Cheat Sheets – packetlife.net

I recently came across this livecd which bundles a collection of network traffic visualisation tools:

• AfterGlow
• TreeMap
• Mondrian
• Parvis
• LGL
• R Project
• InteVis
• EtherApe
• GGobi
• Tulip
• Cytoscape
• GUESS
• RT3DG
• Walrus
• Dottty and lneato
• GraphViz
• glTail
• Shoki
• TimeSearcher
• TNV
• NVisionIP
• Rumint
• MRTG/RRD
• GnuPlot
• Ploticus

http://www.secviz.org/node/89

Paglo is a tool that can be used to discover IT systems and data and monitor and solve computer, network, and other IT related problems.  To use it you need to register an account and download and install a client, which is able to crawl your network.  Paglo supports different plugins that allow you to grab data from your IT systems:

-Directory Server (requires Windows credentials and IP of Directory server)
-Microsoft Exchange Information (requires Windows credentials)
-SNMP Interface Statistics (requires SNMP credentials and IP of devices)
-Registry Information (requires Windows credentials)
-Remote Commands (requires SSH credentials)
-Rescan Hosts (requires IP address of hosts to rescan, and frequency)
-Switch Harvester (requires SNMP, SSH, and/or Telnet credentials)
-SNMP Harvester (requires SNMP credentials)
-Searchable Folder (requires path to folder)
-WMI Information (requires Windows credentials)
Paglo runs as software as a service (SaaS) so if you plan using it, make sure you have no objections against all your IT related data that Paglo crawls is transmitted and stored on the Paglo server. I contacted the vendor and the response I received is the following:

Thanks for taking the time to respond. We appreciate the fact that you signed up for Paglo. And we understand that SaaS is not for everyone, but I want to make sure one thing is clear. The credentials that you provide the Crawler never leave your network. They are only stored in the Crawler behind your firewall.

No matter, we respect your position.

If you want to give it out a try yourself, register an account and download the clientfrom the official website:

http://www.paglo.com/

NeDi is an open source network management tool. It uses CDP and SNMP to communitate to gather information.  The featurelist of NeDI:

• Network Device Discovery
• Network Node Discovery
• Device Inventory (what versions, modules and module versions)
• Device configuration
• Configuration storage
• VLAN management
• Route Management
• Interface Management
• Network Mapping
• Mapping of interface to node
• Subnet management
• Interface Status
• VTP info
• CLI Access
• Web Access
• Device log management
• Spanning tree topology
• Multicast management
• Device link management
• Stolen node detection

http://www.nedi.ch

Spiceworks is software that can be used to manage the inventorise and manage systems on your network.  Its featurelist as published on their website:

• Software inventory, network inventory, PC inventory. Inventory every IT thing you manage.
• Network monitoring, Exchange monitoring, license monitoring and more. Stay alert!
• Asset reporting, inventory reporting… share a report. Report to your heart’s content!
• Helpdesk & IT Portal. Let ‘em submit a ticket! Now you can track every IT task and project.

A free version of the software is available which includes some adds, or you can pay for a license which does not display any adds.

http://www.spiceworks.com/

Pandora FMS is an open source monitoring application to watch systems and applications. It has agents for monitoring Windows (2000, XP, 2003), GNU/Linux, Solaris, HP-UX, BSD, AIX, IPSO and OpenWRT and can monitor load balancing systems, routers, switches, printers, etc through SNMP and TCP/ICMP checks.

You can download Pandora FMS tgz and rpm packages here or download a vmware virtual appliance from the virtual appliances section of the vmware website.

http://pandora.sourceforge.net/

Splunk is can be used to earch, navigate, alert and report on all your IT data in real time. Logs, configurations, messages, traps and alerts, script, code, metrics and more. Splunk is the perfect complement to Nagios. Nagios monitors your network for problems and Splunk helps you get to the root cause.

http://www.splunk.com/

Sguil (pronounced sgweel) is built by network security analysts for network security analysts. Sguil’s main component is an intuitive GUI that provides access to realtime events, session data, and raw packet captures. Sguil facilitates the practice of Network Security Monitoring and event driven analysis. The Sguil client is written in tcl/tk and can be run on any operating system that supports tcl/tk (including Linux, *BSD, Solaris, MacOS, and Win32).

http://www.sguil.net/

Openpacket is a free service providing network traces that can be used to analyze how attacks took place on your network. Uploading your own traces on the website is also possible.

https://www.openpacket.org/