Securing your instalation and server

Hi there another post here goes
 
I would like some advise on how to secure my server, it is fedora 13(32bit)
some advise on securing the controle panel loggin so it uses
 
And general tips on safety to avoid my server being used as a spam machine for emails
 
Thank you

In HCnix we have allowed customers to configure/authenticate relay. For Sendmail Mail Server, sendmail.mc file is provided with the installer; also a comprehensive set of instructions and required files, to configure pop-before-smtp is provided with the installer in folder /usr/local/hostingcontroller/config/sendmail

Using above confirmation you can protect mail services from spam.