ip link set $INTERFACE up
ip addr add  10.0.0.3/32 dev $INTERFACE
ip route add 10.0.0.0/24 dev $INTERFACE

ip route del 10.0.0.0/24 dev $INTERFACE
ip addr del 10.0.0.3/32 dev $INTERFACE
ip link set $INTERFACE down

Subnet = 10.0.0.3/32

Address = foo.bar.net
Port = 655
Subnet = 10.0.0.1/32

foo@local:~ » route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         192.168.0.254   0.0.0.0         UG    202    0        0 enp0s3
10.0.0.0        0.0.0.0         255.255.255.0   U     0      0        0 alpha
192.168.0.0     0.0.0.0         255.255.255.0   U     202    0        0 enp0s3

ip link set $INTERFACE up
VPN_GATEWAY=10.0.0.1
ORIGINAL_GATEWAY=`ip route show | grep ^default | cut -d ' ' -f 2-5`

ip route add $REMOTEADDRESS $ORIGINAL_GATEWAY
ip route add $VPN_GATEWAY dev $INTERFACE
ip route add 0.0.0.0/1 via $VPN_GATEWAY dev $INTERFACE
ip route add 128.0.0.0/1 via $VPN_GATEWAY dev $INTERFACE

ORIGINAL_GATEWAY=`ip route show | grep ^default | cut -d ' ' -f 2-5`

ip route del $REMOTEADDRESS $ORIGINAL_GATEWAY
ip route del $VPN_GATEWAY dev $INTERFACE
ip route del 0.0.0.0/1 dev $INTERFACE
ip route del 128.0.0.0/1 dev $INTERFACE
ip link set $INTERFACE down