Setting a static route.

In this example we want a device to understand how to route all traffic on the 10.1.2.x subnet

In Linux you would run a command like this:

sudo route add -net 10.1.2.0/8 gw 192.168.56.10

Or a command like this:

sudo route add -net 10.1.2.0 netmask 255.255.255.0 gw 192.168.56.10

And if you wanted this rule to persist after reboot, the you would need to add this post-up line to /etc/network/interfaces:

post-up route add -net 10.1.2.0 netmask 255.255.255.0 gw 192.168.56.10

To view the routing table you would run this route command:

route -n

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An example of the same for macOS.

In macOS you would run a command like this:

sudo route -n add -net 10.1.2.0/8 192.168.56.10

To view the routing table in macOS you would run this Netstat command:

netstat -nr