Traffic Forwarder using IPTables
To make a linux box act as the gateway for a NAT (in this example, 10.10.2.0/24) using IPTables, run:
# Enables forwarding. Same effect with 'sysctl net.ipv4.ip_forward=1' echo 1 > /proc/sys/net/ipv4/ip_forward # Define $INSIDE as the interface going into the NAT # Define $OUTSIDE as the interface going to the internet # Route traffic destined to 10.10.2.0/24 to $INSIDE route add -net 10.10.2.0/24 dev $INSIDE # Masquerade traffic going to $OUTSIDE iptables -t nat -A POSTROUTING -o $OUTSIDE -j MASQUERADE # Forward traffic coming from $INSIDE iptables -A FORWARD -i $INSIDE -j ACCEPT
Add additional tweaks as required to the firewall. You will probably want to run
iptables-save to make the changes persistent.