Gateway Padrão

# route -n
Tabela de Roteamento IP do Kernel
Destino         Roteador        MáscaraGen.    Opções Métrica Ref   Uso Iface
0.0.0.0         10.0.2.2        0.0.0.0         UG    0      0        0 eth0
10.0.2.0        0.0.0.0         255.255.255.0   U     0      0        0 eth0
198.51.100.0   0.0.0.0         255.255.255.0   U     0      0        0 eth1
203.0.113.0    0.0.0.0         255.255.255.0   U     0      0        0 eth2

Para versão a partir do Debian 8 e CentOS 7:

# ip route show
default via 198.51.100.1 dev eth0 
169.254.0.0/16 dev eth0  scope link  metric 1002 
198.51.100.0/24 dev eth0  proto kernel  scope link  src 198.51.100.20