Protect Your Linode: Resources
IP Tables GUI ConfigServer Services (standalone and webmin)
DenyHosts (auto-ban SSH attacks)
Fail2ban (Harden Apache/FTP/MTAs)
PortSentry (works with IPTables)
Tripwire (ubuntu) - baseline CRC file checking
TIGER (The Unix security audit and intrusion detection tool)
PHP Hardening
2 Replies
@fhumayun:
DenyHosts (auto-ban SSH attacks)
Fail2ban (Harden Apache/FTP/MTAs)
What about just uninstalling FTP and disabling password-based SSH logins? You can't beat that.
Other tools you listed may be useful for some people, though.
Note that the core features of Suhosin are already part of Debian and Ubuntu's PHP packages. The rest of Suhosin's features can be enabled by installing php5-suhosin, though it's usually unnecessary.
As usual, the most important thing is to know when you need a tool, and to use the tool properly. People who think that they'll be safe just because they installed a certain program are even scarier than the bad guys themselves.