Iptables firewall rules are only memory resident. So when the machine reboots the rules will go bye bye. To make the rules you entered permanent on a Redhat system use the following command:

/sbin/service iptables save

Here are some of the rules I use to setup firewalls on my machines. Please note I am not a iptables guru so you can have a more secure setup than this. Setting up tables and chains is a true art. Iptables will really rock your mum once you learn all the NAT and masqu stuff.
But boy o' boy it sure iz crazy! <- (Said with a Zim voice)

##########################################################################
####################### WEBTRENDS MACHINE ################################
# Defaults
iptables -P FORWARD ACCEPT
iptables -P INPUT ACCEPT
iptables -P OUTPUT ACCEPT

# Delete any existing chains
iptables -F
iptables -X

# Allow loopback traffic.
iptables -A INPUT -i lo -j ACCEPT

# Allow SSH
iptables -A INPUT -p tcp --syn --destination-port 22 -j ACCEPT

# Allow Domain
iptables -A INPUT -p udp --destination-port 53 -j ACCEPT
iptables -A INPUT -p tcp --syn --destination-port 53 -j ACCEPT

# Allow FTP
iptables -A INPUT -p tcp --syn --destination-port 21 -j ACCEPT
iptables -A INPUT -p tcp --syn --destination-port 50000:50020 -j ACCEPT

# Allow http
iptables -A INPUT -p tcp --syn --destination-port 80 -j ACCEPT

# Allow IRC
iptables -A INPUT -p tcp --syn --destination-port 6667 -j ACCEPT

# Allow 'ping'
iptables -A INPUT -p icmp --icmp-type echo-request -j ACCEPT

# Allow Webtrends Admin
iptables -A INPUT -p tcp --syn --destination-port 1099 -j ACCEPT

# Allow Teamspeak Server
iptables -A INPUT -p tcp --syn --destination-port 14534 -j ACCEPT
iptables -A INPUT -p tcp --syn --destination-port 51234 -j ACCEPT

# Allow certain critical ICMP types
iptables -A INPUT -p icmp --icmp-type destination-unreachable -j ACCEPT # Dest unreachable
iptables -A INPUT -p icmp --icmp-type time-exceeded -j ACCEPT # Time exceeded
iptables -A INPUT -p icmp --icmp-type parameter-problem -j ACCEPT # Parameter Problem

##############################################################
# Block all other access
# This must be the last command
iptables -A INPUT -p tcp --syn -j DROP
##############################################################

END

##########################################################################
############################### WEB SERVER ###############################
# Defaults
iptables -P FORWARD ACCEPT
iptables -P INPUT ACCEPT
iptables -P OUTPUT ACCEPT

# Delete any existing chains
iptables -F
iptables -X

# Allow loopback traffic.
iptables -A INPUT -i lo -j ACCEPT

# Allow SSH
iptables -A INPUT -s 209.240.224.0/255.255.255.0 -p tcp --syn --destination-port 22 -j ACCEPT
iptables -A INPUT -s 209.240.254.0/255.255.255.0 -p tcp --syn --destination-port 22 -j ACCEPT
iptables -A INPUT -s 216.135.249.0/255.255.255.0 -p tcp --syn --destination-port 22 -j ACCEPT

# Allow secure server
iptables -A INPUT -p tcp -i eth0 --dport 443 -j ACCEPT
iptables -A INPUT -p udp -i eth0 --dport 443 -j ACCEPT

# Allow Domain
iptables -A INPUT -p udp --destination-port 53 -j ACCEPT
iptables -A INPUT -p tcp --syn --destination-port 53 -j ACCEPT

# Allow FTP
iptables -A INPUT -p tcp --syn --destination-port 21 -j ACCEPT
iptables -A INPUT -p tcp --syn --destination-port 50000:50020 -j ACCEPT

# Allow http
iptables -A INPUT -p tcp --destination-port 80 -j ACCEPT

# Allow 'ping'
iptables -A INPUT -p icmp --icmp-type echo-request -j ACCEPT

# Allow certain critical ICMP types
iptables -A INPUT -p icmp --icmp-type destination-unreachable -j ACCEPT # Dest unreachable
iptables -A INPUT -p icmp --icmp-type time-exceeded -j ACCEPT # Time exceeded
iptables -A INPUT -p icmp --icmp-type parameter-problem -j ACCEPT # Parameter Problem

##############################################################
# Block all other access
# This must be the last command
iptables -A INPUT -p tcp --syn -j DROP
##############################################################

END

 ##########################################################################
############################ MAIL SERVER #################################
# Defaults
iptables -P FORWARD ACCEPT
iptables -P INPUT ACCEPT
iptables -P OUTPUT ACCEPT

# Delete any existing chains
iptables -F
iptables -X

# Allow loopback traffic.
iptables -A INPUT -i lo -j ACCEPT

# Allow SSH
iptables -A INPUT -p tcp --syn --destination-port 22 -j ACCEPT

# Allow Domain
iptables -A INPUT -p udp --destination-port 53 -j ACCEPT
iptables -A INPUT -p tcp --syn --destination-port 53 -j ACCEPT

# Allow http
iptables -A INPUT -p tcp --syn --destination-port 80 -j ACCEPT

# Allow pop
iptables -A INPUT -p tcp --destination-port pop3 -j ACCEPT

# Allow smtp
iptables -A INPUT -p tcp --destination-port smtp -j ACCEPT

# Allow 'ping'
iptables -A INPUT -p icmp --icmp-type echo-request -j ACCEPT

# Allow certain critical ICMP types
iptables -A INPUT -p icmp --icmp-type destination-unreachable -j ACCEPT # Dest unreachable
iptables -A INPUT -p icmp --icmp-type time-exceeded -j ACCEPT # Time exceeded
iptables -A INPUT -p icmp --icmp-type parameter-problem -j ACCEPT # Parameter Problem

##############################################################
# Block all other access
# This must be the last command
iptables -A INPUT -p tcp --syn -j DROP
##############################################################