super secure OS
I need super secure OS for my server - When I open my IP in browser My server has to send me words "hello world" only. I don't need any additional services and open ports. It should be the most secure and bullet-proof.
Which linux distro is for this purpose the best? thanks
Any number of distros could provide what you're looking for. I think if you did a basic install of Debian without any desktop, then installed apache you would pretty much have what you're looking for. Have a look at the Debian netinstall. You'll need a working internet connection but you only download what you need.
Debian -- Network install from a minimal CD
You could use something like CentOS and then enable SELinux on it. Of course, first you should do the standard hardening by turning off all unneeded services, use a firewall, don't allow remote root logins, disable ssh, get rid of SUID bits, etc.
The most secure OS in the world is OpenBSD but if you want linux, both of the above systems are good.
Im using CentOS for servers, and just setup default Policy DROP in iptables, for more secure, tunning systcl.conf and ssh confing.