one@localhost:~$ route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         192.168.3.1     0.0.0.0         UG    0      0        0 enp37s0
192.168.3.0     0.0.0.0         255.255.255.0   U     0      0        0 enp37s0

one@localhost:~$ ifconfig
enp37s0   Link encap:Ethernet  HWaddr 70:85:c2:7c:fa:ec
          inet addr:192.168.3.57  Bcast:192.168.3.255  Mask:255.255.255.0
          inet6 addr: fe80::7285:c2ff:fe7c:faec/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:12496 errors:0 dropped:0 overruns:0 frame:0
          TX packets:9955 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:7131864 (7.1 MB)  TX bytes:1643970 (1.6 MB)

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:166 errors:0 dropped:0 overruns:0 frame:0
          TX packets:166 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:12412 (12.4 KB)  TX bytes:12412 (12.4 KB)

brctl addbr br0 tunctl -u
kvmuser -t tap0 ifconfig enp37s0 up
ifconfig tap0 up
brctl addif br0 enp37s0
brctl addif br0 tap0
ifconfig br0 192.168.3.57 netmask 255.255.255.0 up
route add default gw 192.168.3.1

root@localhost:/home/one# ip route list
default via 192.168.3.1 dev enp37s0
192.168.3.0/24 dev enp37s0  proto kernel  scope link  src 192.168.3.57