20,21: FTP. Note that ftp will use a "random high port number" if the client is in PORT mode, so you may need to add a port range into your /etc/proftpd.conf file to allow ftp connections, eg:
PassivePorts 35000 35999
and then open that port range as well in your firewall.
22: ssh...
There was a time when I was about to select a firewall for a server which had DirectAdmin installed and I choosed CSF. CSF is one of the best firewall available for hosting servers.
Installation of CSF in directAdmin is really easy, just download csf.
Extract it
and Install it
Just a 3...
If you wish to use both php4 and php5 at the same time, custombuild will allow you to do this.
Note that you must have the 2 copies of php running as different types, one as CLI and one as CGI (suPhp). You cannot have both running as CLI, and similarly you cannot have both running as...