If your machine has at least two interfaces in addition to lo0, or if your machine has at least one point-to-point interface, it will automatically be set up as a router. Solaris 2.x: The IP layer will normally act as a router (forwarding datagrams that are not addressed to it, among other things) when the machine has two or more interfaces that are up. This behavior can be overridden by using ndd(1M) to set the /dev/ip variable, ip_forwarding. The value 0 means do not forward; the value 1 means forward.