From CSOonline.com
A list of free-to-download tools for the budget-pinched CISO
BartPE: Preinstalled Environment
Troubled by that incessant spyware or virus that just doesn't seem to go away? Need a way to troubleshoot a system without booting the operating system installed on it? BartPE and the right plug-ins will let you do this. www.nu2.nu/pebuilder
Snort: Open Source Intrusion Detection System
Arguably the world's most used Intrusion Detection System. Both Windows and Linux binaries are available. www.snort.org
VMWare Server: A virtual environment
It finally happened: VMWare is available for free. Patch management, QA, vulnerability remediation testing and other daily activities are now available without a significant capital investment. VMWare also offers images of various environments, configurations and operating systems available for download (they're called "appliances") and ready to use in conjunction with the main product. Just download, point VMWare to the image and test away! www.vmware.com/products/server
DataRescue's IDA Pro Freeware 4.3 disassembler and debugger
Although not posted on the DataRescue site anymore, the free version of their utility will turn up with a quick Google dig. Try www.programmersheaven.com/
OllyDbg disassembler and debugger
Probably the world's most used debugger disassembler. Gives most commercial debuggers a good run for their money. www.ollydbg.de
eEye Digital Security's Binary Diffing Suite
A good, free suite of binary diffing tools you can use to see the effect that a released patch may have on your environment. Read the website, as there are some platform dependencies. research.eeye.com/html/tools/RT20060801-1.html
Cygwin: Linux-like environment for Windows
Need to run some scripts or programs that previously ran only under Linux? Do you miss your Linux command line when running Windows? www.cygwin.com
Nagios: An open-source host, service and network monitoring program
Not for security only, but Nagios can be used to monitor for events that typically have security implications. This is one that you and your CIO will agree upon. www.nagios.org
iptables and Firewall Builder: Firewall and Management Interface
Don't have the deep pockets for a Checkpoint, Cisco or Juniper? Iptables comes with most Linux distributions. Not comfortable using a command line to manage it? Firewall Builder is an intuitive way to install and manage the rule set. Get a couple of credit card CDs, create a bootable distribution, and you've got a firewall in your pocket. www.iptables.org and www.fwbuilder.org
Apache SpamAssassin: Fight Spam at the Gateway
Not really a secret to most people. With the right configuration this is difficult to beat no matter how much you spend on an antispam solution. spamassassin.apache.org/index.html
OpenSSH for Windows: Secure Shell for Windows
Because FTP is so passé (and insecure), use OpenSSH on the server side coupled with "PuTTY" and WinSCP on the client side for a cheap way to secure your file transfers. sshwindows.sourceforge.net, www.chiark.greenend.org.uk/~sgtatham/putty and winscp.net
Cheops-ng: "The Network Swiss Army Knife"
A tool for mapping and monitoring your network. This is an excellent free way to track down most of the systems on your network. cheops-ng.sourceforge.net/download.php
ACID (Analysis Console for Intrusion Databases):
An analysis engine to search and process security events generated by various intrusion detection systems, firewalls and network monitoring tools. acidlab.sourceforge.net