CentOS firewall config

# vi /etc/sysconfig/iptables

# HTTP
-A INPUT -m state --state NEW -m tcp -p tcp --dport 80 -j ACCEPT

# NFS
-A INPUT -m state --state NEW -m udp -p udp --dport 2049 -j ACCEPT
-A INPUT -m state --state NEW -m tcp -p tcp --dport 2049 -j ACCEPT
-A INPUT -m state --state NEW -m udp -p udp --dport 111 -j ACCEPT
-A INPUT -m state --state NEW -m tcp -p tcp --dport 111 -j ACCEPT
-A INPUT -m state --state NEW -m udp -p udp --dport 32769 -j ACCEPT
-A INPUT -m state --state NEW -m tcp -p tcp --dport 32803 -j ACCEPT
-A INPUT -m state --state NEW -m udp -p udp --dport 892 -j ACCEPT
-A INPUT -m state --state NEW -m tcp -p tcp --dport 892 -j ACCEPT
-A INPUT -m state --state NEW -m udp -p udp --dport 875 -j ACCEPT
-A INPUT -m state --state NEW -m tcp -p tcp --dport 875 -j ACCEPT
-A INPUT -m state --state NEW -m udp -p udp --dport 662 -j ACCEPT
-A INPUT -m state --state NEW -m tcp -p tcp --dport 662 -j ACCEPT

# Samba
-A INPUT -m state --state NEW -m udp -p udp --dport 137 -j ACCEPT
-A INPUT -m state --state NEW -m udp -p udp --dport 138 -j ACCEPT
-A INPUT -m state --state NEW -m tcp -p tcp --dport 139 -j ACCEPT
-A INPUT -m state --state NEW -m tcp -p tcp --dport 445 -j ACCEPT
-A INPUT -m state --state NEW -m udp -p udp --dport 445 -j ACCEPT

# /etc/init.d/iptables restart

References:
CentOS / Redhat Iptables Firewall Configuration Tutorial

DNAT (Virtual Server)

# modprobe iptable_nat

# echo "1" > /proc/sys/net/ipv4/ip_forward
 

# iptables -t nat -A PREROUTING -i ppp0 -p tcp --dport 9999 -j DNAT --to-destination 192.168.44.200:9999