useful security tools

• http://www.net-square.com/httprint/ - web server fingherprint tool
• logwatch - log file analysis daily
  
• swatch - simple logfile watcher
• portsentry
• http://osiris.shmoo.com/ - host intergrity tool
• ssldump
• www.securityfocus.com

Forensic Analysis

• Penguin Sleuth Kit(www.linux-forensics.com)
  
• F.I.R.E (Forensic and Incident Response Environment) http://fire.dmzs.com
• BSD fans, use Snarl Bootal Forensics CD http://snarl.eecue.com/

Permanently delete files or hard disk

• shred -n 3 -vz filename (-u)
  

note: random data for 3 pass ( -n 3), be verbose (-v) and write a final pass of zeros over the file after completing the random overwrite passes (z),
if you don't specify -n 3, it will overwrite 25 times by default.
In most cases, when you shredding a file, you would also use -u option to tell shred to truncate the delete the file after overwriting it.

• shred -n 3 -vz /dev/hda
• Darik's Boot and Nuke http://dban.sf.net