#iptables -t nat -A PREROUTING -p tcp -s 192.168.20.121 -j DNAT --to-destination 192.168.99.7


iptables -t mangle -A PREROUTING -p tcp -s 192.168.20.121 -j ROUTE --gw 192.168.99.7



iptables -t nat -A PREROUTING -i eth0 -s 192.168.20.121 -p tcp -j DNAT --to 192.168.99.7
iptables -t nat -A POSTROUTING -o eth1 -s 192.168.20.121 -d 192.168.99.7 -j SNAT --to 192.168.20.22
iptables -A FORWARD -s 192.168.20.121 -d 192.168.99.7 -i eth0 -o eth1 -p tcp -j ACCEPT


#IPTABLES -t nat -A PREROUTING -p tcp --dport 80 -s 192.168.1.140 -j DNAT --to-destination <external_ip>:3128


#iptables -t nat -A PREROUTING -i eth0 -s ! squid-box -p tcp --dport 80 -j DNAT --to squid-box:3128
#iptables -t nat -A POSTROUTING -o eth0 -s local-network -d squid-box -j SNAT --to iptables-box
#iptables -A FORWARD -s local-network -d squid-box -i eth0 -o eth0 -p tcp --dport 3128 -j ACCEPT