Free tools to protect your Windows box from ddos attacks

Harden-it

Harden-it is a security tool for your Windows box to harden the TCP/IP stack and thereby provide protection from denial of service attacks. It also hardens your local system thereby blocking many worms and other sort of malware. Some of Harden-it features include enabling SYN flood protection once the attack is detected and specifying the maximum total amount of both free connections plus those in the SYN_RCVD state. You can download Harden-it from http://www.yasc.net/hardenit.shtml.

PC tools firewall plus

PC tools firewall plus is a freeware Windows firewall software that allows none-sophisticated users a change to setup the firewall easily however allows advanced users to write custom packet filtering rules.  Even though PC tools firewall plus is a firewall rather for home user than server you can also use it on Windows Server 2003. Download PC tools firewall plus from http://www.pctools.com/firewall/

WIPFW

WIPFW (Windows IP Firewall) is Windows version of open source FreeBSD project, IPFW, a packet filtering and accounting system. IPFW consists of 2 parts – firewall part that does packet filtering and IP accounting part that tracks the use of router.

You can download WIPFW here: http://sourceforge.net/project/showfiles.php?group_id=113599