Linux Shell Scripting Cookbook - Third Edition

Reporting routes with ip route

When packets don't reach their destination (ping or traceroute fail), the first thing an experienced user checks is the cables. The next thing to check is the routing tables. If a system lacks a default gateway (0.0.0.0), it will only find machines on its physical network. If you have multiple networks running on the same wires, you'll need to add routes to allow machines attached to one network to send packets to another.

The ip route command reports known routes:

$ ip route
10.8.0.2 dev tun0  proto kernel  scope link  src 10.8.0.1 
192.168.87.0/24 dev vmnet1  proto kernel  scope link  src 192.168.87.1 
192.168.1.0/24 dev eth0  proto kernel  scope link  src 192.168.1.44 
default via 192.168.1.1 dev eth0 proto static ...