I have two gateways with different ISP, one of them defined as default for the LAN user and the other ISP used as the default for the Servers and VPN traffic. This is done using regular routing tables configured with the DHCP.
Now I want Google drive and some other software traffic installed in the LAN users laptops that uses a lot of upload to always use the other ISP that is not defined as their default gw. How can I accomplish that??
My initial thoughts are use IPTABLES or squid.
I have been trying with this
iptables -t nat -A PREROUTING -d GOOGLE_IP -j DNAT --to-destination MY_SECOND_ISP
iptables -t nat -A POSTROUTING -s MY_SECOND_ISP -j SNAT --to-source GOOGLE_IP
iptables -t nat -A POSTROUTING -s MY_SECOND_ISP -j MASQUERADE
but it does not work. When I test it the traffic goes to the default gw
Any idea how to do it using iptables, shorewall or squid??