Software and Tutorial Links

IPTables
Linux firewall with packet string-matching support
http://www.securityfocus.com/infocus/1531
Firewall scripts
http://linuxfirewall.start.bg/
http://www.puschitz.com/FirewallAndRouters.shtml
Debian Kernel how-to
http://myfreesoft.net/phpBB2/viewtopic.php?t=52 * in Bulgarian *
Source: http://www.howtoforge.com/forums/showthread.php?t=21
http://www.howtoforge.com/kernel_compilation_debian
Active Ports (Windows)
http://www.microsoft.com/technet/sysinternals/Networking/TcpView.mspx
Security and Audits Checks & updates
http://sourceforge.net/projects/advchk
RedHat – http://www.redhat.com/spacewalk/