what does this line do?
 

what does this line do? #chmod +x /etc/rc.firewall
do I have to make a script executable before I place it in /etc/rc.d ?
if so how do I do that?

The # probably indicates that it should be done as root. chmod +x /etc/rc.firewall makes the file /etc/rc.firewall executable.

And yes, you should make scripts executable since they are of little use if they are not (I know someone could argue you could use bash scriptname but that's not the point, is it?).

How to make something executable? You just posted an example on how to do it. :)

Håkan

Thank you.

Depending - the pound # can also be a comment - ie., the code is not supposed to execute.