AV, Anti-RootKit, And Firewall For Dedi

trying to secure my new server that will be opening for shared hosting.

So far I've found:

CHKRootKit, RKHunter, and ClamAV

As for Firewall, I've setup CSF but my question is, what is a good setting for blocking SYN Floods without blocking clients who might be browsing their site and, using DA, and FTP.

In the past I've used:

iptables -A INPUT -p tcp --syn -m limit --limit 1/s --limit-burst 3 -j DROP
iptables -A INPUT -p tcp --syn -m limit --limit 3/s --limit-burst 5 -j DROP
and took down some pretty big attacks, but it was very touchy.