How to add a permanant route in OpenBSD

add a line to /etc/hostname.[if_name]
!route add -net [network_ip/cidr] [gateway_ip]
!route add -host [host_ip] [gateway_ip]

# Add a network
!route add -net 10.10.1.0/24 172.18.1.1

#Add a host
!route add -host 10.10.1.18 172.18.1.1