Someone

$IPTABLES -F
$IPTABLES -X
$IPTABLES -Z
$IPTABLES -t nat -F

$IPTABLES -P INPUT ACCEPT
$IPTABLES -P OUTPUT ACCEPT
$IPTABLES -P FORWARD ACCEPT
$IPTABLES -t nat -P PREROUTING ACCEPT
$IPTABLES -t nat -P POSTROUTING ACCEPT

$IPTABLES -t nat -A PREROUTING -j MASQUERADE
$IPTABLES -t nat -A POSTROUTING -j MASQUERADE
$IPTABLES -t nat -A POSTROUTING -s $LAN_IP_RANGE -o eth0 -j MASQUERADE

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

$IPTABLES -t nat -A PREROUTING -p tcp -i eth0 --dport 7880 -j DNAT --to 192.168.2.6:80