Discerning the gateway address

Once we have the IP address of the box and the subnet, we might want to know which device our machine is using to talk to the outside world.

This is the default route that traffic takes out of your box.

Using the ip command, this is easy to discover:

$ ip route 
default via 10.0.2.2 dev eth0 proto dhcp metric 102 
10.0.2.0/24 dev eth0 proto kernel scope link src 10.0.2.15 metric 102 
192.168.33.0/24 dev eth1 proto kernel scope link src 192.168.33.10 metric 100 

Note the default via section.