### /etc/network/interfaces

auto lo
iface lo inet loopback

# The primary network interface
allow-hotplug eth0
iface eth0 inet dhcp

auto eth0

iface eth0 inet static
address 192.168.186.151/17

# ip -4 a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
3: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    inet 45.33.4.25/24 brd 45.33.4.255 scope global eth0
       valid_lft forever preferred_lft forever

# ip -4 r

default via 45.33.4.1 dev eth0
45.33.4.0/24 dev eth0  proto kernel  scope link  src 45.33.4.25