I have a routing problem. I know exactly what I want to do. I know it is possible from looking through older posts of similar problems. But I haven't been able to find the correct solution yet. I have a linux firewall box (Ubuntu 16.04). The box has 4 network interfaces. Our ISP modem is connected to Interface A. What I want to do is setup source routing where for all packets coming in, by default go to interface B - connected to router 1, but for one client's IP ranges I want the packets to go to interface C - connected to router 2.
Any help is appreciated, J