Since someone brought it up and i pm him but someone suggested to tell everyone i'll tell.
Red Hat Linux Has its own firewall so you don't need to buy any new ones. If you enable the firewall in red hat linux you can limit people to access your file.

No Firewall
If you choose no firewall your computer better be in a network you trust in better not be in internet.
Enable Firewall
If you choose to enable firewall, connections that are not allowed by your will not be accepted.
For more info visit
http://www.redhat.com/docs/
http://www.nsa.gov/selinux/
This info is provided by Talkwebz.com place where you talk about webs.
If that helped you please give me a green rep.