El siguiente script en bash es el primer prototipo de LoadBalancer para un servicio TCP en dos o mas servidores simultaneamente utilizando iptables.
#!/bin/bash
local_ip="10.10.50.81"
ip1="10.10.96.50"
ip2="10.10.50.106"
tcp_port="80"
#Se valida que los servicios esten disponibles
nmap $ip1 -p $tcp_port | grep -i open >> /dev/null
service1=$?
nmap $ip2 -p $tcp_port | grep -i open >> /dev/null
service2=$?
let status=$service1+$service2
echo "Valor: $status"
let remakerules=10
while [ 0 -eq 0 ]; do
if [ "$remakerules" != "$status" ]; then
# You need these system settings.
echo 1 > /proc/sys/net/ipv4/ip_forward
for f in /proc/sys/net/ipv4/conf/*/rp_filter ; do echo 1 > $f ; done
# Clear iptables/netfilter settings.
iptables -F
iptables -X
iptables -t nat -F
iptables -t nat -X
iptables -t filter -F
iptables -t filter -X
iptables -t mangle -F
iptables -t mangle -X
iptables -P INPUT ACCEPT
iptables -P OUTPUT ACCEPT
iptables -P FORWARD ACCEPT
iptables -t nat -P PREROUTING ACCEPT
iptables -t nat -P POSTROUTING ACCEPT
if [ "$service1" == "0" -a "$service2" == "0" ]; then
#Los dos servicios estan disponibles
iptables -t nat -A PREROUTING -p tcp -d $local_ip --dport $tcp_port -m state --state NEW -m statistic --mode random --probability .5 -j DNAT --to $ip1:$tcp_port
iptables -t nat -A PREROUTING -p tcp -d $local_ip --dport $tcp_port -m state --state NEW -m statistic --mode random --probability .5 -j DNAT --to $ip2:$tcp_port
else
if [ "$service2" == "0" ]; then
#Unicamente el servicio2 esta arriba
iptables -t nat -A PREROUTING -p tcp -d $local_ip --dport $tcp_port -m state --state NEW -m statistic --mode nth --every 1 --packet 0 -j DNAT --to $ip2:$tcp_port
else
if [ "$service1" == "0" ]; then
#Unicamente el servicio1 esta arriba
iptables -t nat -A PREROUTING -p tcp -d $local_ip --dport $tcp_port -m state --state NEW -m statistic --mode nth --every 1 --packet 0 -j DNAT --to $ip1:$tcp_port
else
echo "CRITICAL: Los dos Servicios estan abajo"
fi
fi
fi
iptables -A INPUT -j ACCEPT
iptables -A OUTPUT -j ACCEPT
iptables -A FORWARD -j ACCEPT
iptables -A INPUT -j LOG --log-prefix "iptables: " --log-level 4
iptables -A OUTPUT -j LOG --log-prefix "iptables: " --log-level 4
iptables -A FORWARD -j LOG --log-prefix "iptables: " --log-level 4
iptables -t nat -A POSTROUTING -j MASQUERADE
echo "Cambio de reglas..."
fi
#sleep 1200
sleep 1
#Se valida que los servicios esten disponibles
nmap $ip1 -p $tcp_port | grep -i open >> /dev/null
service1=$?
nmap $ip2 -p $tcp_port | grep -i open >> /dev/null
service2=$?
let remakerules=$status
let status=$service1+$service2
echo "Valor: $status"
done
