The default CentOS installation does not have port 80 and 443 open, which you need for HTTP and HTTPS. To open up those ports and start serving website, add the following two lines in /etc/sysconfig/iptables
# -A RH-Firewall-1-INPUT -p tcp -m tcp --dport 443 -j ACCEPT
# -A RH-Firewall-1-INPUT -p tcp -m tcp --dport 80 -j ACCEPT
Restart iptables with this command: # service iptables restart

Nice!! Just what I wanted.
If you create the rule for http using building system-config-firewall it’s slightly different.
This is what the rule looks like
-A INPUT -m state –state NEW -m tcp -p tcp –dport 80 -j ACCEPT
@Jaime Gago -Perfect Answer. Tnx
[...] port 80 is closed. I'm not running SL, but you may follow the instructions here to open the port in iptables. It's written for Centos, but it can apply to SL as it's compatible [...]