$ ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: gre0@NONE: <NOARP> mtu 1476 qdisc noop state DOWN group default qlen 1
    link/gre 0.0.0.0 brd 0.0.0.0
3: gretap0@NONE: <BROADCAST,MULTICAST> mtu 1462 qdisc noop state DOWN group default qlen 1000
    link/ether 00:00:00:00:00:00 brd ff:ff:ff:ff:ff:ff
12: eth0@if13: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1300 qdisc noqueue state UP group default qlen 1000
    link/ether fa:16:3e:d7:7d:ce brd ff:ff:ff:ff:ff:ff link-netnsid 0
    inet 192.168.21.7/24 brd 192.168.21.255 scope global eth0
       valid_lft forever preferred_lft forever
    inet6 fe80::f816:3eff:fed7:7dce/64 scope link 
       valid_lft forever preferred_lft forever


$ curl -s http://169.254.169.254/openstack/2016-10-06/network_data.json | python3 -m json.tool
{
    "services": [
        {
            "type": "dns",
            "address": "10.245.160.2"
        }
    ],
    "networks": [
        {
            "network_id": "82fb3880-217e-48cf-8c15-75333cc7fb87",
            "link": "tapc19a40e4-2d",
            "type": "ipv4_dhcp",
            "id": "network0"
        }
    ],
    "links": [
        {
            "ethernet_mac_address": "fa:16:3e:d7:7d:ce",
            "mtu": 1458,
            "type": "ovs",
            "id": "tapc19a40e4-2d",
            "vif_id": "c19a40e4-2db1-4c11-946c-74efd9b1f678"
        }
    ]
}

$ sudo sh -c 'cd /sys/class/net && grep -r . *' 2>errs; cat errs
eth0/mtu:1300
eth0/type:1
eth0/netdev_group:0
eth0/flags:0x1003
eth0/power/control:auto
eth0/power/async:disabled
eth0/power/runtime_enabled:disabled
eth0/power/runtime_active_kids:0
eth0/power/runtime_active_time:0
eth0/power/runtime_status:unsupported
eth0/power/runtime_usage:0
eth0/power/runtime_suspended_time:0
eth0/speed:10000
eth0/dormant:0
eth0/name_assign_type:4
eth0/proto_down:0
eth0/addr_assign_type:3
eth0/dev_id:0x0
eth0/duplex:full
eth0/gro_flush_timeout:0
eth0/iflink:13
eth0/addr_len:6
eth0/address:fa:16:3e:d7:7d:ce
eth0/operstate:up
eth0/carrier_changes:2
eth0/broadcast:ff:ff:ff:ff:ff:ff
eth0/queues/rx-0/rps_flow_cnt:0
eth0/queues/rx-0/rps_cpus:0
eth0/queues/tx-0/xps_cpus:0
eth0/queues/tx-0/tx_maxrate:0
eth0/queues/tx-0/tx_timeout:0
eth0/queues/tx-0/byte_queue_limits/limit:0
eth0/queues/tx-0/byte_queue_limits/limit_max:1879048192
eth0/queues/tx-0/byte_queue_limits/limit_min:0
eth0/queues/tx-0/byte_queue_limits/hold_time:1000
eth0/queues/tx-0/byte_queue_limits/inflight:0
eth0/tx_queue_len:1000
eth0/uevent:INTERFACE=eth0
eth0/uevent:IFINDEX=12
eth0/statistics/rx_fifo_errors:0
eth0/statistics/collisions:0
eth0/statistics/rx_errors:0
eth0/statistics/rx_compressed:0
eth0/statistics/rx_dropped:0
eth0/statistics/tx_packets:7738
eth0/statistics/tx_errors:0
eth0/statistics/rx_missed_errors:0
eth0/statistics/rx_over_errors:0
eth0/statistics/tx_carrier_errors:0
eth0/statistics/tx_heartbeat_errors:0
eth0/statistics/rx_crc_errors:0
eth0/statistics/multicast:0
eth0/statistics/tx_fifo_errors:0
eth0/statistics/tx_aborted_errors:0
eth0/statistics/rx_bytes:24876508
eth0/statistics/tx_compressed:0
eth0/statistics/tx_dropped:0
eth0/statistics/rx_packets:10513
eth0/statistics/tx_bytes:1070735
eth0/statistics/tx_window_errors:0
eth0/statistics/rx_frame_errors:0
eth0/statistics/rx_length_errors:0
eth0/dev_port:0
eth0/ifindex:12
eth0/link_mode:0
eth0/carrier:1
gre0/mtu:1476
gre0/type:778
gre0/netdev_group:0
gre0/flags:0x80
gre0/power/control:auto
gre0/power/async:disabled
gre0/power/runtime_enabled:disabled
gre0/power/runtime_active_kids:0
gre0/power/runtime_active_time:0
gre0/power/runtime_status:unsupported
gre0/power/runtime_usage:0
gre0/power/runtime_suspended_time:0
gre0/proto_down:0
gre0/addr_assign_type:0
gre0/dev_id:0x0
gre0/gro_flush_timeout:0
gre0/iflink:0
gre0/addr_len:4
gre0/address:00:00:00:00
gre0/operstate:down
gre0/carrier_changes:0
gre0/broadcast:00:00:00:00
gre0/queues/rx-0/rps_flow_cnt:0
gre0/queues/rx-0/rps_cpus:0
gre0/queues/tx-0/xps_cpus:0
gre0/queues/tx-0/tx_maxrate:0
gre0/queues/tx-0/tx_timeout:0
gre0/queues/tx-0/byte_queue_limits/limit:0
gre0/queues/tx-0/byte_queue_limits/limit_max:1879048192
gre0/queues/tx-0/byte_queue_limits/limit_min:0
gre0/queues/tx-0/byte_queue_limits/hold_time:1000
gre0/queues/tx-0/byte_queue_limits/inflight:0
gre0/tx_queue_len:1
gre0/uevent:INTERFACE=gre0
gre0/uevent:IFINDEX=2
gre0/statistics/rx_fifo_errors:0
gre0/statistics/collisions:0
gre0/statistics/rx_errors:0
gre0/statistics/rx_compressed:0
gre0/statistics/rx_dropped:0
gre0/statistics/tx_packets:0
gre0/statistics/tx_errors:0
gre0/statistics/rx_missed_errors:0
gre0/statistics/rx_over_errors:0
gre0/statistics/tx_carrier_errors:0
gre0/statistics/tx_heartbeat_errors:0
gre0/statistics/rx_crc_errors:0
gre0/statistics/multicast:0
gre0/statistics/tx_fifo_errors:0
gre0/statistics/tx_aborted_errors:0
gre0/statistics/rx_bytes:0
gre0/statistics/tx_compressed:0
gre0/statistics/tx_dropped:0
gre0/statistics/rx_packets:0
gre0/statistics/tx_bytes:0
gre0/statistics/tx_window_errors:0
gre0/statistics/rx_frame_errors:0
gre0/statistics/rx_length_errors:0
gre0/dev_port:0
gre0/ifindex:2
gre0/link_mode:0
gretap0/mtu:1462
gretap0/type:1
gretap0/netdev_group:0
gretap0/flags:0x1002
gretap0/power/control:auto
gretap0/power/async:disabled
gretap0/power/runtime_enabled:disabled
gretap0/power/runtime_active_kids:0
gretap0/power/runtime_active_time:0
gretap0/power/runtime_status:unsupported
gretap0/power/runtime_usage:0
gretap0/power/runtime_suspended_time:0
gretap0/proto_down:0
gretap0/addr_assign_type:0
gretap0/dev_id:0x0
gretap0/gro_flush_timeout:0
gretap0/iflink:0
gretap0/addr_len:6
gretap0/address:00:00:00:00:00:00
gretap0/operstate:down
gretap0/carrier_changes:0
gretap0/broadcast:ff:ff:ff:ff:ff:ff
gretap0/queues/rx-0/rps_flow_cnt:0
gretap0/queues/rx-0/rps_cpus:0
gretap0/queues/tx-0/xps_cpus:0
gretap0/queues/tx-0/tx_maxrate:0
gretap0/queues/tx-0/tx_timeout:0
gretap0/queues/tx-0/byte_queue_limits/limit:0
gretap0/queues/tx-0/byte_queue_limits/limit_max:1879048192
gretap0/queues/tx-0/byte_queue_limits/limit_min:0
gretap0/queues/tx-0/byte_queue_limits/hold_time:1000
gretap0/queues/tx-0/byte_queue_limits/inflight:0
gretap0/tx_queue_len:1000
gretap0/uevent:INTERFACE=gretap0
gretap0/uevent:IFINDEX=3
gretap0/statistics/rx_fifo_errors:0
gretap0/statistics/collisions:0
gretap0/statistics/rx_errors:0
gretap0/statistics/rx_compressed:0
gretap0/statistics/rx_dropped:0
gretap0/statistics/tx_packets:0
gretap0/statistics/tx_errors:0
gretap0/statistics/rx_missed_errors:0
gretap0/statistics/rx_over_errors:0
gretap0/statistics/tx_carrier_errors:0
gretap0/statistics/tx_heartbeat_errors:0
gretap0/statistics/rx_crc_errors:0
gretap0/statistics/multicast:0
gretap0/statistics/tx_fifo_errors:0
gretap0/statistics/tx_aborted_errors:0
gretap0/statistics/rx_bytes:0
gretap0/statistics/tx_compressed:0
gretap0/statistics/tx_dropped:0
gretap0/statistics/rx_packets:0
gretap0/statistics/tx_bytes:0
gretap0/statistics/tx_window_errors:0
gretap0/statistics/rx_frame_errors:0
gretap0/statistics/rx_length_errors:0
gretap0/dev_port:0
gretap0/ifindex:3
gretap0/link_mode:0
lo/mtu:65536
lo/type:772
lo/netdev_group:0
lo/flags:0x9
lo/power/control:auto
lo/power/async:disabled
lo/power/runtime_enabled:disabled
lo/power/runtime_active_kids:0
lo/power/runtime_active_time:0
lo/power/runtime_status:unsupported
lo/power/runtime_usage:0
lo/power/runtime_suspended_time:0
lo/dormant:0
lo/proto_down:0
lo/addr_assign_type:0
lo/dev_id:0x0
lo/gro_flush_timeout:0
lo/iflink:1
lo/addr_len:6
lo/address:00:00:00:00:00:00
lo/operstate:unknown
lo/carrier_changes:0
lo/broadcast:00:00:00:00:00:00
lo/queues/rx-0/rps_flow_cnt:0
lo/queues/rx-0/rps_cpus:0
lo/queues/tx-0/xps_cpus:0
lo/queues/tx-0/tx_maxrate:0
lo/queues/tx-0/tx_timeout:0
lo/queues/tx-0/byte_queue_limits/limit:0
lo/queues/tx-0/byte_queue_limits/limit_max:1879048192
lo/queues/tx-0/byte_queue_limits/limit_min:0
lo/queues/tx-0/byte_queue_limits/hold_time:1000
lo/queues/tx-0/byte_queue_limits/inflight:0
lo/tx_queue_len:1
lo/uevent:INTERFACE=lo
lo/uevent:IFINDEX=1
lo/statistics/rx_fifo_errors:0
lo/statistics/collisions:0
lo/statistics/rx_errors:0
lo/statistics/rx_compressed:0
lo/statistics/rx_dropped:0
lo/statistics/tx_packets:0
lo/statistics/tx_errors:0
lo/statistics/rx_missed_errors:0
lo/statistics/rx_over_errors:0
lo/statistics/tx_carrier_errors:0
lo/statistics/tx_heartbeat_errors:0
lo/statistics/rx_crc_errors:0
lo/statistics/multicast:0
lo/statistics/tx_fifo_errors:0
lo/statistics/tx_aborted_errors:0
lo/statistics/rx_bytes:0
lo/statistics/tx_compressed:0
lo/statistics/tx_dropped:0
lo/statistics/rx_packets:0
lo/statistics/tx_bytes:0
lo/statistics/tx_window_errors:0
lo/statistics/rx_frame_errors:0
lo/statistics/rx_length_errors:0
lo/dev_port:0
lo/ifindex:1
lo/link_mode:0
lo/carrier:1
sudo: unable to resolve host xenial-133359
grep: eth0/phys_port_name: Operation not supported
grep: eth0/power/autosuspend_delay_ms: Input/output error
grep: eth0/phys_switch_id: Operation not supported
grep: eth0/phys_port_id: Operation not supported
grep: gre0/phys_port_name: Operation not supported
grep: gre0/power/autosuspend_delay_ms: Input/output error
grep: gre0/speed: Invalid argument
grep: gre0/dormant: Invalid argument
grep: gre0/name_assign_type: Invalid argument
grep: gre0/phys_switch_id: Operation not supported
grep: gre0/duplex: Invalid argument
grep: gre0/phys_port_id: Operation not supported
grep: gre0/carrier: Invalid argument
grep: gretap0/phys_port_name: Operation not supported
grep: gretap0/power/autosuspend_delay_ms: Input/output error
grep: gretap0/speed: Invalid argument
grep: gretap0/dormant: Invalid argument
grep: gretap0/name_assign_type: Invalid argument
grep: gretap0/phys_switch_id: Operation not supported
grep: gretap0/duplex: Invalid argument
grep: gretap0/phys_port_id: Operation not supported
grep: gretap0/carrier: Invalid argument
grep: lo/phys_port_name: Operation not supported
grep: lo/power/autosuspend_delay_ms: Input/output error
grep: lo/speed: Invalid argument
grep: lo/name_assign_type: Invalid argument
grep: lo/phys_switch_id: Operation not supported
grep: lo/duplex: Invalid argument
grep: lo/phys_port_id: Operation not supported