#!/bin/bash


echo "Activation du routage"
echo 1 > /proc/sys/net/ipv4/ip_forward


# -t indicates which interfaces we use
#here when there a new packet connection, "mangle" applies
#-F delete all the rules in the "mangle" table
iptables -t mangle --flush
echo "previous rules for mangle table have been deleted"

#all the counters to 0
iptables --zero
echo "counters to 0"

echo "Which interface ?"
read int

#--tee Make a copy of the packet, and route that copy to the given destination. For the original, uncopied packet, behave like a non-terminating target and continue traversing the rules.
#--gw IP_address Route the packet via this gateway
iptables -t mangle -A PREROUTING -i $int -j ROUTE -tee --gw 192.168.1.250

#FORWARD : The FORWARD policy allows an administrator to control where packets can be routed within a LAN.
#for the default "filter" table, add rule (-A) to the FORWARD chain by autorizing traffic action, -j ACCEPT.
iptables -A FORWARD --in-interface $int -j ACCEPT
echo "Forwarding packets to $int"

#MASQUERADE: modify packet in order to hide some informations about his origin
#for 'mangle' table, add rule for routing modified packet by an interface.
iptables -t mangle -A POSTROUTING --out-interface $int -j MASQUERADE
echo "postrouting packets by $int are falsified"

# Forward to the gateway

echo "redirection faite"

exit