diff --git a/python/vyos/ifconfig.py b/python/vyos/ifconfig.py
index 1ffa10978..3470b3aa6 100644
--- a/python/vyos/ifconfig.py
+++ b/python/vyos/ifconfig.py
@@ -1,1514 +1,1513 @@
 # Copyright 2019 VyOS maintainers and contributors <maintainers@vyos.io>
 #
 # This library is free software; you can redistribute it and/or
 # modify it under the terms of the GNU Lesser General Public
 # License as published by the Free Software Foundation; either
 # version 2.1 of the License, or (at your option) any later version.
 #
 # This library is distributed in the hope that it will be useful,
 # but WITHOUT ANY WARRANTY; without even the implied warranty of
 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 # Lesser General Public License for more details.
 #
 # You should have received a copy of the GNU Lesser General Public
 # License along with this library.  If not, see <http://www.gnu.org/licenses/>.
 
 import os
 import re
 import jinja2
 import json
 
 from vyos.validate import *
 from ipaddress import IPv4Network, IPv6Address
 from netifaces import ifaddresses, AF_INET, AF_INET6
 from subprocess import Popen, PIPE, STDOUT
 from time import sleep
 
 dhclient_base = r'/var/lib/dhcp/dhclient_'
 dhcp_cfg = """
 # generated by ifconfig.py
 option rfc3442-classless-static-routes code 121 = array of unsigned integer 8;
 timeout 60;
 retry 300;
 
 interface "{{ intf }}" {
     send host-name "{{ hostname }}";
     {% if client_id -%}
     send dhcp-client-identifier "{{ client_id }}";
     {% endif -%}
     {% if vendor_class_id -%}
     send vendor-class-identifier "{{ vendor_class_id }}";
     {% endif -%}
     request subnet-mask, broadcast-address, routers, domain-name-servers,
         rfc3442-classless-static-routes, domain-name, interface-mtu;
     require subnet-mask;
 }
 
 """
 
 dhcpv6_cfg = """
 # generated by ifconfig.py
 interface "{{ intf }}" {
     request routers, domain-name-servers, domain-name;
 }
 
 """
 
 class Interface:
     def __init__(self, ifname, type=None):
         """
         This is the base interface class which supports basic IP/MAC address
         operations as well as DHCP(v6). Other interface which represent e.g.
         and ethernet bridge are implemented as derived classes adding all
         additional functionality.
 
         DEBUG:
         This class has embedded debugging (print) which can be enabled by
         creating the following file:
         vyos@vyos# touch /tmp/vyos.ifconfig.debug
 
         Example:
         >>> from vyos.ifconfig import Interface
         >>> i = Interface('eth0')
         """
         self._ifname = str(ifname)
 
         if not os.path.exists('/sys/class/net/{}'.format(ifname)) and not type:
             raise Exception('interface "{}" not found'.format(self._ifname))
 
         if not os.path.exists('/sys/class/net/{}'.format(self._ifname)):
             cmd = 'ip link add dev {} type {}'.format(self._ifname, type)
             self._cmd(cmd)
 
         # per interface DHCP config files
         self._dhcp_cfg_file = dhclient_base + self._ifname + '.conf'
         self._dhcp_pid_file = dhclient_base + self._ifname + '.pid'
         self._dhcp_lease_file = dhclient_base + self._ifname + '.leases'
 
         # per interface DHCPv6 config files
         self._dhcpv6_cfg_file = dhclient_base + self._ifname + '.v6conf'
         self._dhcpv6_pid_file = dhclient_base + self._ifname + '.v6pid'
         self._dhcpv6_lease_file = dhclient_base + self._ifname + '.v6leases'
 
         # DHCP options
         self._dhcp_options = {
             'intf' : self._ifname,
             'hostname' : '',
             'client_id' : '',
             'vendor_class_id' : ''
         }
 
         # DHCPv6 options
         self._dhcpv6_options = {
             'intf' : self._ifname,
             'dhcpv6_prm_only' : False,
             'dhcpv6_temporary' : False
         }
 
     def _debug_msg(self, msg):
         if os.path.isfile('/tmp/vyos.ifconfig.debug'):
             print('DEBUG/{:<6} {}'.format(self._ifname, msg))
 
     def _cmd(self, command):
         p = Popen(command, stdout=PIPE, stderr=STDOUT, shell=True)
         tmp = p.communicate()[0].strip()
         self._debug_msg("cmd '{}'".format(command))
         if tmp.decode():
             self._debug_msg("returned:\n{}".format(tmp.decode()))
 
         # do we need some error checking code here?
         return tmp.decode()
 
     def _read_sysfs(self, filename):
         """
         Provide a single primitive w/ error checking for reading from sysfs.
         """
         value = None
         with open(filename, 'r') as f:
             value = f.read().rstrip('\n')
 
         self._debug_msg("read '{}' < '{}'".format(value, filename))
         return value
 
     def _write_sysfs(self, filename, value):
         """
         Provide a single primitive w/ error checking for writing to sysfs.
         """
         self._debug_msg("write '{}' > '{}'".format(value, filename))
         with open(filename, 'w') as f:
             f.write(str(value))
 
         return None
 
     def remove(self):
         """
         Remove interface from operating system. Removing the interface
         deconfigures all assigned IP addresses and clear possible DHCP(v6)
         client processes.
 
         Example:
         >>> from vyos.ifconfig import Interface
         >>> i = Interface('eth0')
         >>> i.remove()
         """
         # stop DHCP(v6) if running
         self._del_dhcp()
         self._del_dhcpv6()
 
         # remove all assigned IP addresses from interface - this is a bit redundant
         # as the kernel will remove all addresses on interface deletion, but we
         # can not delete ALL interfaces, see below
         for addr in self.get_addr():
             self.del_addr(addr)
 
         # Ethernet interfaces can not be removed
         if type(self) == type(EthernetIf(self._ifname)):
             return
 
         # NOTE (Improvement):
         # after interface removal no other commands should be allowed
         # to be called and instead should raise an Exception:
         cmd = 'ip link del dev {}'.format(self._ifname)
         return self._cmd(cmd)
 
     def get_mtu(self):
         """
         Get/set interface mtu in bytes.
 
         Example:
         >>> from vyos.ifconfig import Interface
         >>> Interface('eth0').get_mtu()
         '1500'
         """
         return self._read_sysfs('/sys/class/net/{}/mtu'
                                 .format(self._ifname))
 
     def set_mtu(self, mtu):
         """
         Get/set interface mtu in bytes.
 
         Example:
         >>> from vyos.ifconfig import Interface
         >>> Interface('eth0').set_mtu(1400)
         >>> Interface('eth0').get_mtu()
         '1400'
         """
         if mtu < 68 or mtu > 9000:
             raise ValueError('Invalid MTU size: "{}"'.format(mru))
 
         return self._write_sysfs('/sys/class/net/{}/mtu'
                                  .format(self._ifname), mtu)
 
     def set_mac(self, mac):
         """
         Set interface MAC (Media Access Contrl) address to given value.
 
         Example:
         >>> from vyos.ifconfig import Interface
         >>> Interface('eth0').set_mac('00:50:ab:cd:ef:01')
         """
         # on interface removal (ethernet) an empty string is passed - ignore it
         if not mac:
             return None
 
         # a mac address consits out of 6 octets
         octets = len(mac.split(':'))
         if octets != 6:
             raise ValueError('wrong number of MAC octets: {} '.format(octets))
 
         # validate against the first mac address byte if it's a multicast
         # address
         if int(mac.split(':')[0], 16) & 1:
             raise ValueError('{} is a multicast MAC address'.format(mac))
 
         # overall mac address is not allowed to be 00:00:00:00:00:00
         if sum(int(i, 16) for i in mac.split(':')) == 0:
             raise ValueError('00:00:00:00:00:00 is not a valid MAC address')
 
         # check for VRRP mac address
         if mac.split(':')[0] == '0' and addr.split(':')[1] == '0' and mac.split(':')[2] == '94' and mac.split(':')[3] == '0' and mac.split(':')[4] == '1':
             raise ValueError('{} is a VRRP MAC address'.format(mac))
 
         # Assemble command executed on system. Unfortunately there is no way
         # of altering the MAC address via sysfs
         cmd = 'ip link set dev {} address {}'.format(self._ifname, mac)
         return self._cmd(cmd)
 
 
     def set_arp_cache_tmo(self, tmo):
         """
         Set ARP cache timeout value in seconds. Internal Kernel representation
         is in milliseconds.
 
         Example:
         >>> from vyos.ifconfig import Interface
         >>> Interface('eth0').set_arp_cache_tmo(40)
         """
         return self._write_sysfs('/proc/sys/net/ipv4/neigh/{0}/base_reachable_time_ms'
                                  .format(self._ifname), (int(tmo) * 1000))
 
     def set_link_detect(self, link_filter):
         """
         Configure kernel response in packets received on interfaces that are 'down'
 
         0 - Allow packets to be received for the address on this interface
             even if interface is disabled or no carrier.
 
         1 - Ignore packets received if interface associated with the incoming
             address is down.
 
         2 - Ignore packets received if interface associated with the incoming
             address is down or has no carrier.
 
         Default value is 0. Note that some distributions enable it in startup
         scripts.
 
         Example:
         >>> from vyos.ifconfig import Interface
         >>> Interface('eth0').set_link_detect(1)
         """
         if int(link_filter) >= 0 and int(link_filter) <= 2:
             return self._write_sysfs('/proc/sys/net/ipv4/conf/{0}/link_filter'
                                      .format(self._ifname), link_filter)
         else:
             raise ValueError("Value out of range")
 
     def set_alias(self, ifalias=None):
         """
         Set interface alias name used by e.g. SNMP
 
         Example:
         >>> from vyos.ifconfig import Interface
         >>> Interface('eth0').set_alias('VyOS upstream interface')
 
         to clear alias e.g. delete it use:
 
         >>> Interface('eth0').set_ifalias('')
         """
         if not ifalias:
             # clear interface alias
             ifalias = '\0'
 
         self._write_sysfs('/sys/class/net/{}/ifalias'
                           .format(self._ifname), ifalias)
 
     def get_state(self):
         """
         Enable (up) / Disable (down) an interface
 
         Example:
         >>> from vyos.ifconfig import Interface
         >>> Interface('eth0').get_state()
         'up'
         """
         cmd = 'ip -json link show dev {}'.format(self._ifname)
         tmp = self._cmd(cmd)
         out = json.loads(tmp)
         return out[0]['operstate'].lower()
 
     def set_state(self, state):
         """
         Enable (up) / Disable (down) an interface
 
         Example:
         >>> from vyos.ifconfig import Interface
         >>> Interface('eth0').set_state('down')
         >>> Interface('eth0').get_state()
         'down'
         """
         if state not in ['up', 'down']:
             raise ValueError('state must be "up" or "down"')
 
         # Assemble command executed on system. Unfortunately there is no way
         # to up/down an interface via sysfs
         cmd = 'ip link set dev {} {}'.format(self._ifname, state)
         return self._cmd(cmd)
 
     def set_proxy_arp(self, enable):
         """
         Set per interface proxy ARP configuration
 
         Example:
         >>> from vyos.ifconfig import Interface
         >>> Interface('eth0').set_proxy_arp(1)
         """
         if int(enable) >= 0 and int(enable) <= 1:
             return self._write_sysfs('/proc/sys/net/ipv4/conf/{}/proxy_arp'
                                      .format(self._ifname), enable)
         else:
             raise ValueError("Value out of range")
 
     def set_proxy_arp_pvlan(self, enable):
         """
         Private VLAN proxy arp.
         Basically allow proxy arp replies back to the same interface
         (from which the ARP request/solicitation was received).
 
         This is done to support (ethernet) switch features, like RFC
         3069, where the individual ports are NOT allowed to
         communicate with each other, but they are allowed to talk to
         the upstream router.  As described in RFC 3069, it is possible
         to allow these hosts to communicate through the upstream
         router by proxy_arp'ing. Don't need to be used together with
         proxy_arp.
 
         This technology is known by different names:
         In RFC 3069 it is called VLAN Aggregation.
         Cisco and Allied Telesyn call it Private VLAN.
         Hewlett-Packard call it Source-Port filtering or port-isolation.
         Ericsson call it MAC-Forced Forwarding (RFC Draft).
 
         Example:
         >>> from vyos.ifconfig import Interface
         >>> Interface('eth0').set_proxy_arp_pvlan(1)
         """
         if int(enable) >= 0 and int(enable) <= 1:
             return self._write_sysfs('/proc/sys/net/ipv4/conf/{}/proxy_arp_pvlan'
                                      .format(self._ifname), enable)
         else:
             raise ValueError("Value out of range")
 
     def get_addr(self):
         """
         Retrieve assigned IPv4 and IPv6 addresses from given interface.
         This is done using the netifaces and ipaddress python modules.
 
         Example:
         >>> from vyos.ifconfig import Interface
         >>> Interface('eth0').get_addrs()
         ['172.16.33.30/24', 'fe80::20c:29ff:fe11:a174/64']
         """
 
         ipv4 = []
         ipv6 = []
 
         if AF_INET in ifaddresses(self._ifname).keys():
             for v4_addr in ifaddresses(self._ifname)[AF_INET]:
                 # we need to manually assemble a list of IPv4 address/prefix
                 prefix = '/' + \
                     str(IPv4Network('0.0.0.0/' + v4_addr['netmask']).prefixlen)
                 ipv4.append(v4_addr['addr'] + prefix)
 
         if AF_INET6 in ifaddresses(self._ifname).keys():
             for v6_addr in ifaddresses(self._ifname)[AF_INET6]:
                 # Note that currently expanded netmasks are not supported. That means
                 # 2001:db00::0/24 is a valid argument while 2001:db00::0/ffff:ff00:: not.
                 # see https://docs.python.org/3/library/ipaddress.html
                 bits = bin(
                     int(v6_addr['netmask'].replace(':', ''), 16)).count('1')
                 prefix = '/' + str(bits)
 
                 # we alsoneed to remove the interface suffix on link local
                 # addresses
                 v6_addr['addr'] = v6_addr['addr'].split('%')[0]
                 ipv6.append(v6_addr['addr'] + prefix)
 
         return ipv4 + ipv6
 
     def add_addr(self, addr):
         """
         Add IP(v6) address to interface. Address is only added if it is not
         already assigned to that interface.
 
         addr: can be an IPv4 address, IPv6 address, dhcp or dhcpv6!
               IPv4: add IPv4 address to interface
               IPv6: add IPv6 address to interface
               dhcp: start dhclient (IPv4) on interface
               dhcpv6: start dhclient (IPv6) on interface
 
         Example:
         >>> from vyos.ifconfig import Interface
         >>> j = Interface('eth0')
         >>> j.add_addr('192.0.2.1/24')
         >>> j.add_addr('2001:db8::ffff/64')
         >>> j.get_addr()
         ['192.0.2.1/24', '2001:db8::ffff/64']
         """
         if addr == 'dhcp':
             self._set_dhcp()
         elif addr == 'dhcpv6':
             self._set_dhcpv6()
         else:
             if not is_intf_addr_assigned(self._ifname, addr):
                 cmd = 'ip addr add "{}" dev "{}"'.format(addr, self._ifname)
                 return self._cmd(cmd)
 
     def del_addr(self, addr):
         """
         Delete IP(v6) address to interface. Address is only added if it is
         assigned to that interface.
 
         addr: can be an IPv4 address, IPv6 address, dhcp or dhcpv6!
               IPv4: delete IPv4 address from interface
               IPv6: delete IPv6 address from interface
               dhcp: stop dhclient (IPv4) on interface
               dhcpv6: stop dhclient (IPv6) on interface
 
         Example:
         >>> from vyos.ifconfig import Interface
         >>> j = Interface('eth0')
         >>> j.add_addr('2001:db8::ffff/64')
         >>> j.add_addr('192.0.2.1/24')
         >>> j.get_addr()
         ['192.0.2.1/24', '2001:db8::ffff/64']
         >>> j.del_addr('192.0.2.1/24')
         >>> j.get_addr()
         ['2001:db8::ffff/64']
         """
         if addr == 'dhcp':
             self._del_dhcp()
         elif addr == 'dhcpv6':
             self._del_dhcpv6()
         else:
             if is_intf_addr_assigned(self._ifname, addr):
                 cmd = 'ip addr del "{}" dev "{}"'.format(addr, self._ifname)
                 return self._cmd(cmd)
 
 
     def get_dhcp_options(self):
         """
         Return dictionary with supported DHCP options.
 
         Dictionary should be altered and send back via set_dhcp_options()
         so those options are applied when DHCP is run.
         """
         return self._dhcp_options
 
     def set_dhcp_options(self, options):
         """
         Store new DHCP options used by next run of DHCP client.
         """
         self._dhcp_options = options
 
     def get_dhcpv6_options(self):
         """
         Return dictionary with supported DHCPv6 options.
 
         Dictionary should be altered and send back via set_dhcp_options()
         so those options are applied when DHCP is run.
         """
         return self._dhcpv6_options
 
     def set_dhcpv6_options(self, options):
         """
         Store new DHCP options used by next run of DHCP client.
         """
         self._dhcpv6_options = options
 
     # replace dhcpv4/v6 with systemd.networkd?
     def _set_dhcp(self):
         """
         Configure interface as DHCP client. The dhclient binary is automatically
         started in background!
 
         Example:
 
         >>> from vyos.ifconfig import Interface
         >>> j = Interface('eth0')
         >>> j.set_dhcp()
         """
 
         dhcp = self.get_dhcp_options()
         if not dhcp['hostname']:
             # read configured system hostname.
             # maybe change to vyos hostd client ???
             with open('/etc/hostname', 'r') as f:
                 dhcp['hostname'] = f.read().rstrip('\n')
 
         # render DHCP configuration
         tmpl = jinja2.Template(dhcp_cfg)
         dhcp_text = tmpl.render(dhcp)
         with open(self._dhcp_cfg_file, 'w') as f:
             f.write(dhcp_text)
 
-        if self.get_state() == 'up':
-            cmd  = 'start-stop-daemon --start --quiet --pidfile ' + \
-                self._dhcp_pid_file
-            cmd += ' --exec /sbin/dhclient --'
-            # now pass arguments to dhclient binary
-            cmd += ' -4 -nw -cf {} -pf {} -lf {} {}'.format(
-                self._dhcp_cfg_file, self._dhcp_pid_file, self._dhcp_lease_file, self._ifname)
-            return self._cmd(cmd)
+        cmd  = 'start-stop-daemon --start --quiet --pidfile ' + \
+            self._dhcp_pid_file
+        cmd += ' --exec /sbin/dhclient --'
+        # now pass arguments to dhclient binary
+        cmd += ' -4 -nw -cf {} -pf {} -lf {} {}'.format(
+            self._dhcp_cfg_file, self._dhcp_pid_file, self._dhcp_lease_file, self._ifname)
+        return self._cmd(cmd)
 
 
     def _del_dhcp(self):
         """
         De-configure interface as DHCP clinet. All auto generated files like
         pid, config and lease will be removed.
 
         Example:
 
         >>> from vyos.ifconfig import Interface
         >>> j = Interface('eth0')
         >>> j.del_dhcp()
         """
         pid = 0
         if os.path.isfile(self._dhcp_pid_file):
             with open(self._dhcp_pid_file, 'r') as f:
                 pid = int(f.read())
         else:
             self._debug_msg('No DHCP client PID found')
             return None
 
         # stop dhclient, we need to call dhclient and tell it should release the
         # aquired IP address. tcpdump tells me:
         # 172.16.35.103.68 > 172.16.35.254.67: [bad udp cksum 0xa0cb -> 0xb943!] BOOTP/DHCP, Request from 00:50:56:9d:11:df, length 300, xid 0x620e6946, Flags [none] (0x0000)
         #  Client-IP 172.16.35.103
         #  Client-Ethernet-Address 00:50:56:9d:11:df
         #  Vendor-rfc1048 Extensions
         #    Magic Cookie 0x63825363
         #    DHCP-Message Option 53, length 1: Release
         #    Server-ID Option 54, length 4: 172.16.35.254
         #    Hostname Option 12, length 10: "vyos"
         #
         cmd = '/sbin/dhclient -cf {} -pf {} -lf {} -r {}'.format(
                 self._dhcp_cfg_file, self._dhcp_pid_file, self._dhcp_lease_file, self._ifname)
         self._cmd(cmd)
 
         # cleanup old config file
         if os.path.isfile(self._dhcp_cfg_file):
             os.remove(self._dhcp_cfg_file)
 
         # cleanup old pid file
         if os.path.isfile(self._dhcp_pid_file):
             os.remove(self._dhcp_pid_file)
 
         # cleanup old lease file
         if os.path.isfile(self._dhcp_lease_file):
             os.remove(self._dhcp_lease_file)
 
 
     def _set_dhcpv6(self):
         """
         Configure interface as DHCPv6 client. The dhclient binary is automatically
         started in background!
 
         Example:
 
         >>> from vyos.ifconfig import Interface
         >>> j = Interface('eth0')
         >>> j.set_dhcpv6()
         """
         dhcpv6 = self.get_dhcpv6_options()
         import pprint
         pprint.pprint(dhcpv6)
 
         # better save then sorry .. should be checked in interface script
         # but if you missed it we are safe!
         if dhcpv6['dhcpv6_prm_only'] and dhcpv6['dhcpv6_temporary']:
             raise Exception('DHCPv6 temporary and parameters-only options are mutually exclusive!')
 
         # render DHCP configuration
         tmpl = jinja2.Template(dhcpv6_cfg)
         dhcpv6_text = tmpl.render(dhcpv6)
         with open(self._dhcpv6_cfg_file, 'w') as f:
             f.write(dhcpv6_text)
 
         if self.get_state() == 'up':
             # https://bugs.launchpad.net/ubuntu/+source/ifupdown/+bug/1447715
             #
             # wee need to wait for IPv6 DAD to finish once and interface is added
             # this suxx :-(
             sleep(5)
 
             # no longer accept router announcements on this interface
             self._write_sysfs('/proc/sys/net/ipv6/conf/{}/accept_ra'
                   .format(self._ifname), 0)
 
             # assemble command-line to start DHCPv6 client (dhclient)
             cmd  = 'start-stop-daemon --start --quiet --pidfile ' + \
                 self._dhcpv6_pid_file
             cmd += ' --exec /sbin/dhclient --'
             # now pass arguments to dhclient binary
             cmd += ' -6 -nw -cf {} -pf {} -lf {}'.format(
                 self._dhcpv6_cfg_file, self._dhcpv6_pid_file, self._dhcpv6_lease_file)
 
             # add optional arguments
             if dhcpv6['dhcpv6_prm_only']:
                 cmd += ' -S'
             if dhcpv6['dhcpv6_temporary']:
                 cmd += ' -T'
 
             cmd += ' {}'.format(self._ifname)
             return self._cmd(cmd)
 
 
     def _del_dhcpv6(self):
         """
         De-configure interface as DHCPv6 clinet. All auto generated files like
         pid, config and lease will be removed.
 
         Example:
 
         >>> from vyos.ifconfig import Interface
         >>> j = Interface('eth0')
         >>> j.del_dhcpv6()
         """
         pid = 0
         if os.path.isfile(self._dhcpv6_pid_file):
             with open(self._dhcpv6_pid_file, 'r') as f:
                 pid = int(f.read())
         else:
             self._debug_msg('No DHCPv6 client PID found')
             return None
 
         # stop dhclient
         cmd = 'start-stop-daemon --stop --quiet --pidfile {}'.format(self._dhcpv6_pid_file)
         self._cmd(cmd)
 
         # accept router announcements on this interface
         self._write_sysfs('/proc/sys/net/ipv6/conf/{}/accept_ra'
               .format(self._ifname), 1)
 
         # cleanup old config file
         if os.path.isfile(self._dhcpv6_cfg_file):
             os.remove(self._dhcpv6_cfg_file)
 
         # cleanup old pid file
         if os.path.isfile(self._dhcpv6_pid_file):
             os.remove(self._dhcpv6_pid_file)
 
         # cleanup old lease file
         if os.path.isfile(self._dhcpv6_lease_file):
             os.remove(self._dhcpv6_lease_file)
 
 
 class LoopbackIf(Interface):
 
     """
     The loopback device is a special, virtual network interface that your router
     uses to communicate with itself.
     """
 
     def __init__(self, ifname):
         super().__init__(ifname, type='loopback')
 
     def remove(self):
         """
         Loopback interface can not be deleted from operating system. We can
         only remove all assigned IP addresses.
 
         Example:
         >>> from vyos.ifconfig import Interface
         >>> i = LoopbackIf('lo').remove()
         """
         # remove all assigned IP addresses from interface
         for addr in self.get_addr():
             self.del_addr(addr)
 
         # question: do we also delerte the loopback address? 127.0.0.1/8
 
 
 class DummyIf(Interface):
 
     """
     A dummy interface is entirely virtual like, for example, the loopback
     interface. The purpose of a dummy interface is to provide a device to route
     packets through without actually transmitting them.
     """
 
     def __init__(self, ifname):
         super().__init__(ifname, type='dummy')
 
 
 class STPIf(Interface):
     """
     A spanning-tree capable interface. This applies only to bridge port member
     interfaces!
     """
     def __init__(self, ifname):
         super().__init__(ifname)
 
     def set_path_cost(self, cost):
         """
         Set interface path cost, only relevant for STP enabled interfaces
 
         Example:
 
         >>> from vyos.ifconfig import Interface
         >>> Interface('eth0').set_path_cost(4)
         """
         if not os.path.isfile('/sys/class/net/{}/brport/path_cost'
                               .format(self._ifname)):
             raise TypeError('{} is not a bridge port member'.format(self._ifname))
 
         return self._write_sysfs('/sys/class/net/{}/brport/path_cost'
                                  .format(self._ifname), cost)
 
     def set_path_priority(self, priority):
         """
         Set interface path priority, only relevant for STP enabled interfaces
 
         Example:
 
         >>> from vyos.ifconfig import Interface
         >>> Interface('eth0').set_path_priority(4)
         """
         if not os.path.isfile('/sys/class/net/{}/brport/priority'
                               .format(self._ifname)):
             raise TypeError('{} is not a bridge port member'.format(self._ifname))
 
         return self._write_sysfs('/sys/class/net/{}/brport/priority'
                                  .format(self._ifname), priority)
 
 
 class BridgeIf(Interface):
 
     """
     A bridge is a way to connect two Ethernet segments together in a protocol
     independent way. Packets are forwarded based on Ethernet address, rather
     than IP address (like a router). Since forwarding is done at Layer 2, all
     protocols can go transparently through a bridge.
 
     The Linux bridge code implements a subset of the ANSI/IEEE 802.1d standard.
     """
 
     def __init__(self, ifname):
         super().__init__(ifname, type='bridge')
 
     def set_ageing_time(self, time):
         """
         Set bridge interface MAC address aging time in seconds. Internal kernel
         representation is in centiseconds. Kernel default is 300 seconds.
 
         Example:
         >>> from vyos.ifconfig import BridgeIf
         >>> BridgeIf('br0').ageing_time(2)
         """
         time = int(time) * 100
         return self._write_sysfs('/sys/class/net/{}/bridge/ageing_time'
                                  .format(self._ifname), time)
 
     def set_forward_delay(self, time):
         """
         Set bridge forwarding delay in seconds. Internal Kernel representation
         is in centiseconds.
 
         Example:
         >>> from vyos.ifconfig import BridgeIf
         >>> BridgeIf('br0').forward_delay(15)
         """
         return self._write_sysfs('/sys/class/net/{}/bridge/forward_delay'
                                  .format(self._ifname), (int(time) * 100))
 
     def set_hello_time(self, time):
         """
         Set bridge hello time in seconds. Internal Kernel representation
         is in centiseconds.
 
         Example:
         >>> from vyos.ifconfig import BridgeIf
         >>> BridgeIf('br0').set_hello_time(2)
         """
         return self._write_sysfs('/sys/class/net/{}/bridge/hello_time'
                                  .format(self._ifname), (int(time) * 100))
 
     def set_max_age(self, time):
         """
         Set bridge max message age in seconds. Internal Kernel representation
         is in centiseconds.
 
         Example:
         >>> from vyos.ifconfig import Interface
         >>> BridgeIf('br0').set_max_age(30)
         """
         return self._write_sysfs('/sys/class/net/{}/bridge/max_age'
                                  .format(self._ifname), (int(time) * 100))
 
     def set_priority(self, priority):
         """
         Set bridge max aging time in seconds.
 
         Example:
         >>> from vyos.ifconfig import BridgeIf
         >>> BridgeIf('br0').set_priority(8192)
         """
         return self._write_sysfs('/sys/class/net/{}/bridge/priority'
                                  .format(self._ifname), priority)
 
     def set_stp(self, state):
         """
         Set bridge STP (Spanning Tree) state. 0 -> STP disabled, 1 -> STP enabled
 
         Example:
         >>> from vyos.ifconfig import BridgeIf
         >>> BridgeIf('br0').set_stp(1)
         """
 
         if int(state) >= 0 and int(state) <= 1:
             return self._write_sysfs('/sys/class/net/{}/bridge/stp_state'
                                      .format(self._ifname), state)
         else:
             raise ValueError("Value out of range")
 
 
     def set_multicast_querier(self, enable):
         """
         Sets whether the bridge actively runs a multicast querier or not. When a
         bridge receives a 'multicast host membership' query from another network
         host, that host is tracked based on the time that the query was received
         plus the multicast query interval time.
 
         Use enable=1 to enable or enable=0 to disable
 
         Example:
         >>> from vyos.ifconfig import Interface
         >>> BridgeIf('br0').set_multicast_querier(1)
         """
         if int(enable) >= 0 and int(enable) <= 1:
             return self._write_sysfs('/sys/class/net/{}/bridge/multicast_querier'
                                      .format(self._ifname), enable)
         else:
             raise ValueError("Value out of range")
 
 
     def add_port(self, interface):
         """
         Add physical interface to bridge (member port)
 
         Example:
         >>> from vyos.ifconfig import Interface
         >>> BridgeIf('br0').add_port('eth0')
         >>> BridgeIf('br0').add_port('eth1')
         """
         cmd = 'ip link set dev {} master {}'.format(interface, self._ifname)
         return self._cmd(cmd)
 
     def del_port(self, interface):
         """
         Remove member port from bridge instance.
 
         Example:
         >>> from vyos.ifconfig import Interface
         >>> BridgeIf('br0').del_port('eth1')
         """
         cmd = 'ip link set dev {} nomaster'.format(interface)
         return self._cmd(cmd)
 
 class VLANIf(Interface):
     """
     This class handels the creation and removal of a VLAN interface. It serves
     as base class for BondIf and EthernetIf.
     """
     def __init__(self, ifname, type=None):
         super().__init__(ifname, type)
 
     def remove(self):
         """
         Remove interface from operating system. Removing the interface
         deconfigures all assigned IP addresses and clear possible DHCP(v6)
         client processes.
 
         Example:
         >>> from vyos.ifconfig import Interface
         >>> i = Interface('eth0')
         >>> i.remove()
         """
         # Do we have sub interfaces (VLANs)? We apply a regex matching
         # subinterfaces (indicated by a .) of a parent interface.
         #
         # As interfaces need to be deleted "in order" starting from Q-in-Q
         # we delete them first.
         vlan_ifs = [f for f in os.listdir(r'/sys/class/net') \
                         if re.match(self._ifname + r'(?:\.\d+)(?:\.\d+)', f)]
 
         for vlan in vlan_ifs:
             Interface(vlan).remove()
 
         # After deleting all Q-in-Q interfaces delete other VLAN interfaces
         # which probably acted as parent to Q-in-Q or have been regular 802.1q
         # interface.
         vlan_ifs = [f for f in os.listdir(r'/sys/class/net') \
                         if re.match(self._ifname + r'(?:\.\d+)', f)]
 
         for vlan in vlan_ifs:
             Interface(vlan).remove()
 
         # All subinterfaces are now removed, continue on the physical interface
         super().remove()
 
 
     def add_vlan(self, vlan_id, ethertype='', ingress_qos='', egress_qos=''):
         """
         A virtual LAN (VLAN) is any broadcast domain that is partitioned and
         isolated in a computer network at the data link layer (OSI layer 2).
         Use this function to create a new VLAN interface on a given physical
         interface.
 
         This function creates both 802.1q and 802.1ad (Q-in-Q) interfaces. Proto
         parameter is used to indicate VLAN type.
 
         A new object of type VLANIf is returned once the interface has been
         created.
 
         @param ethertype: If specified, create 802.1ad or 802.1q Q-in-Q VLAN
                           interface
         @param ingress_qos: Defines a mapping of VLAN header prio field to the
                             Linux internal packet priority on incoming frames.
         @param ingress_qos: Defines a mapping of Linux internal packet priority
                             to VLAN header prio field but for outgoing frames.
 
         Example:
         >>> from vyos.ifconfig import VLANIf
         >>> i = VLANIf('eth0')
         >>> i.add_vlan(10)
         """
         vlan_ifname = self._ifname + '.' + str(vlan_id)
         if not os.path.exists('/sys/class/net/{}'.format(vlan_ifname)):
             self._vlan_id = int(vlan_id)
 
             if ethertype:
                 self._ethertype = ethertype
                 ethertype = 'proto {}'.format(ethertype)
 
             # Optional ingress QOS mapping
             opt_i = ''
             if ingress_qos:
                 opt_i = 'ingress-qos-map ' + ingress_qos
             # Optional egress QOS mapping
             opt_e = ''
             if egress_qos:
                 opt_e = 'egress-qos-map ' + egress_qos
 
             # create interface in the system
             cmd = 'ip link add link {intf} name {intf}.{vlan} type vlan {proto} id {vlan} {opt_e} {opt_i}' \
                    .format(intf=self._ifname, vlan=self._vlan_id, proto=ethertype, opt_e=opt_e, opt_i=opt_i)
             self._cmd(cmd)
 
         # return new object mapping to the newly created interface
         # we can now work on this object for e.g. IP address setting
         # or interface description and so on
         return VLANIf(vlan_ifname)
 
 
     def del_vlan(self, vlan_id):
         """
         Remove VLAN interface from operating system. Removing the interface
         deconfigures all assigned IP addresses and clear possible DHCP(v6)
         client processes.
 
         Example:
         >>> from vyos.ifconfig import VLANIf
         >>> i = VLANIf('eth0.10')
         >>> i.del_vlan()
         """
         vlan_ifname = self._ifname + '.' + str(vlan_id)
         VLANIf(vlan_ifname).remove()
 
 
 class EthernetIf(VLANIf):
     """
     Abstraction of a Linux Ethernet Interface
     """
     def __init__(self, ifname):
         super().__init__(ifname)
 
     def get_driver_name(self):
         """
         Return the driver name used by NIC. Some NICs don't support all
         features e.g. changing link-speed, duplex
 
         Example:
         >>> from vyos.ifconfig import EthernetIf
         >>> i = EthernetIf('eth0')
         >>> i.get_driver_name()
         'vmxnet3'
         """
         link = os.readlink('/sys/class/net/{}/device/driver/module'.format(self._ifname))
         return os.path.basename(link)
 
     def set_flow_control(self, enable):
         """
         Changes the pause parameters of the specified Ethernet device.
 
         @param enable: true -> enable pause frames, false -> disable pause frames
 
         Example:
         >>> from vyos.ifconfig import EthernetIf
         >>> i = EthernetIf('eth0')
         >>> i.set_flow_control(True)
         """
         if enable not in ['on', 'off']:
             raise ValueError("Value out of range")
 
         if self.get_driver_name() in ['vmxnet3', 'virtio_net']:
             self._debug_msg('{} driver does not support changing flow control settings!'
                             .format(self.get_driver_name()))
             return
 
         # Assemble command executed on system. Unfortunately there is no way
         # to change this setting via sysfs
         cmd = '/sbin/ethtool --pause {0} autoneg {1} tx {1} rx {1}'.format(
               self._ifname, enable)
         try:
             # An exception will be thrown if the settings are not changed
             return self._cmd(cmd)
         except CalledProcessError:
             pass
 
 
     def set_speed_duplex(self, speed, duplex):
         """
         Set link speed in Mbit/s and duplex.
 
         @speed can be any link speed in MBit/s, e.g. 10, 100, 1000 auto
         @duplex can be half, full, auto
 
         Example:
         >>> from vyos.ifconfig import EthernetIf
         >>> i = EthernetIf('eth0')
         >>> i.set_speed_duplex('auto', 'auto')
         """
 
         if speed not in ['auto', '10', '100', '1000', '2500', '5000', '10000', '25000', '40000', '50000', '100000', '400000']:
             raise ValueError("Value out of range (speed)")
 
         if duplex not in ['auto', 'full', 'half']:
             raise ValueError("Value out of range (duplex)")
 
         if self.get_driver_name() in ['vmxnet3', 'virtio_net']:
             self._debug_msg('{} driver does not support changing speed/duplex settings!'
                             .format(self.get_driver_name()))
             return
 
 
         cmd = '/sbin/ethtool -s {}'.format(self._ifname)
         if speed == 'auto' or duplex == 'auto':
             cmd += ' autoneg on'
         else:
             cmd += ' speed {} duplex {} autoneg off'.format(speed, duplex)
 
         return self._cmd(cmd)
 
 
     def set_gro(self, state):
         """
         Example:
         >>> from vyos.ifconfig import EthernetIf
         >>> i = EthernetIf('eth0')
         >>> i.set_gro('on')
         """
         if state not in ['on', 'off']:
             raise ValueError('state must be "on" or "off"')
 
         cmd = '/sbin/ethtool -K {} gro {}'.format(self._ifname, state)
         return self._cmd(cmd)
 
 
     def set_gso(self, state):
         """
         Example:
         >>> from vyos.ifconfig import EthernetIf
         >>> i = EthernetIf('eth0')
         >>> i.set_gso('on')
         """
         if state not in ['on', 'off']:
             raise ValueError('state must be "on" or "off"')
 
         cmd = '/sbin/ethtool -K {} gso {}'.format(self._ifname, state)
         return self._cmd(cmd)
 
 
     def set_sg(self, state):
         """
         Example:
         >>> from vyos.ifconfig import EthernetIf
         >>> i = EthernetIf('eth0')
         >>> i.set_sg('on')
         """
         if state not in ['on', 'off']:
             raise ValueError('state must be "on" or "off"')
 
         cmd = '/sbin/ethtool -K {} sg {}'.format(self._ifname, state)
         return self._cmd(cmd)
 
 
     def set_tso(self, state):
         """
         Example:
         >>> from vyos.ifconfig import EthernetIf
         >>> i = EthernetIf('eth0')
         >>> i.set_tso('on')
         """
         if state not in ['on', 'off']:
             raise ValueError('state must be "on" or "off"')
 
         cmd = '/sbin/ethtool -K {} tso {}'.format(self._ifname, state)
         return self._cmd(cmd)
 
 
     def set_ufo(self, state):
         """
         Example:
         >>> from vyos.ifconfig import EthernetIf
         >>> i = EthernetIf('eth0')
         >>> i.set_udp_offload('on')
         """
         if state not in ['on', 'off']:
             raise ValueError('state must be "on" or "off"')
 
         cmd = '/sbin/ethtool -K {} ufo {}'.format(self._ifname, state)
         return self._cmd(cmd)
 
 
 class BondIf(VLANIf):
     """
     The Linux bonding driver provides a method for aggregating multiple network
     interfaces into a single logical "bonded" interface. The behavior of the
     bonded interfaces depends upon the mode; generally speaking, modes provide
     either hot standby or load balancing services. Additionally, link integrity
     monitoring may be performed.
     """
     def __init__(self, ifname):
         super().__init__(ifname, type='bond')
 
     def remove(self):
         """
         Remove interface from operating system. Removing the interface
         deconfigures all assigned IP addresses and clear possible DHCP(v6)
         client processes.
         Example:
         >>> from vyos.ifconfig import Interface
         >>> i = Interface('eth0')
         >>> i.remove()
         """
         # when a bond member gets deleted, all members are placed in A/D state
         # even when they are enabled inside CLI. This will make the config
         # and system look async.
         slave_list = []
         for s in self.get_slaves():
             slave = {
                 'ifname' : s,
                 'state': Interface(s).get_state()
             }
             slave_list.append(slave)
 
         # remove bond master which places members in disabled state
         super().remove()
 
         # replicate previous interface state before bond destruction back to
         # physical interface
         for slave in slave_list:
              i = Interface(slave['ifname'])
              i.set_state(slave['state'])
 
 
     def set_hash_policy(self, mode):
         """
         Selects the transmit hash policy to use for slave selection in
         balance-xor, 802.3ad, and tlb modes. Possible values are: layer2,
         layer2+3, layer3+4, encap2+3, encap3+4.
 
         The default value is layer2
 
         Example:
         >>> from vyos.ifconfig import BondIf
         >>> BondIf('bond0').set_hash_policy('layer2+3')
         """
         if not mode in ['layer2', 'layer2+3', 'layer3+4', 'encap2+3', 'encap3+4']:
             raise ValueError("Value out of range")
         return self._write_sysfs('/sys/class/net/{}/bonding/xmit_hash_policy'
                                  .format(self._ifname), mode)
 
     def set_arp_interval(self, interval):
         """
         Specifies the ARP link monitoring frequency in milliseconds.
 
         The ARP monitor works by periodically checking the slave devices
         to determine whether they have sent or received traffic recently
         (the precise criteria depends upon the bonding mode, and the
         state of the slave). Regular traffic is generated via ARP probes
         issued for the addresses specified by the arp_ip_target option.
 
         If ARP monitoring is used in an etherchannel compatible mode
         (modes 0 and 2), the switch should be configured in a mode that
         evenly distributes packets across all links. If the switch is
         configured to distribute the packets in an XOR fashion, all
         replies from the ARP targets will be received on the same link
         which could cause the other team members to fail.
 
         value of 0 disables ARP monitoring. The default value is 0.
 
         Example:
         >>> from vyos.ifconfig import BondIf
         >>> BondIf('bond0').set_arp_interval('100')
         """
         if int(interval) == 0:
             """
             Specifies the MII link monitoring frequency in milliseconds.
             This determines how often the link state of each slave is
             inspected for link failures. A value of zero disables MII
             link monitoring. A value of 100 is a good starting point.
             """
             return self._write_sysfs('/sys/class/net/{}/bonding/miimon'
                                      .format(self._ifname), interval)
         else:
             return self._write_sysfs('/sys/class/net/{}/bonding/arp_interval'
                                      .format(self._ifname), interval)
 
     def get_arp_ip_target(self):
         """
         Specifies the IP addresses to use as ARP monitoring peers when
         arp_interval is > 0. These are the targets of the ARP request sent to
         determine the health of the link to the targets. Specify these values
         in ddd.ddd.ddd.ddd format. Multiple IP addresses must be separated by
         a comma. At least one IP address must be given for ARP monitoring to
         function. The maximum number of targets that can be specified is 16.
 
         The default value is no IP addresses.
 
         Example:
         >>> from vyos.ifconfig import BondIf
         >>> BondIf('bond0').get_arp_ip_target()
         '192.0.2.1'
         """
         return self._read_sysfs('/sys/class/net/{}/bonding/arp_ip_target'
                                 .format(self._ifname))
 
     def set_arp_ip_target(self, target):
         """
         Specifies the IP addresses to use as ARP monitoring peers when
         arp_interval is > 0. These are the targets of the ARP request sent to
         determine the health of the link to the targets. Specify these values
         in ddd.ddd.ddd.ddd format. Multiple IP addresses must be separated by
         a comma. At least one IP address must be given for ARP monitoring to
         function. The maximum number of targets that can be specified is 16.
 
         The default value is no IP addresses.
 
         Example:
         >>> from vyos.ifconfig import BondIf
         >>> BondIf('bond0').set_arp_ip_target('192.0.2.1')
         >>> BondIf('bond0').get_arp_ip_target()
         '192.0.2.1'
         """
         return self._write_sysfs('/sys/class/net/{}/bonding/arp_ip_target'
                                  .format(self._ifname), target)
 
     def add_port(self, interface):
         """
         Enslave physical interface to bond.
 
         Example:
         >>> from vyos.ifconfig import BondIf
         >>> BondIf('bond0').add_port('eth0')
         >>> BondIf('bond0').add_port('eth1')
         """
         # An interface can only be added to a bond if it is in 'down' state. If
         # interface is in 'up' state, the following Kernel error will  be thrown:
         # bond0: eth1 is up - this may be due to an out of date ifenslave.
         Interface(interface).set_state('down')
 
         return self._write_sysfs('/sys/class/net/{}/bonding/slaves'
                                  .format(self._ifname), '+' + interface)
 
     def del_port(self, interface):
         """
         Remove physical port from bond
 
         Example:
         >>> from vyos.ifconfig import BondIf
         >>> BondIf('bond0').del_port('eth1')
         """
         return self._write_sysfs('/sys/class/net/{}/bonding/slaves'
                                  .format(self._ifname), '-' + interface)
 
     def get_slaves(self):
         """
         Return a list with all configured slave interfaces on this bond.
 
         Example:
         >>> from vyos.ifconfig import BondIf
         >>> BondIf('bond0').get_slaves()
         ['eth1', 'eth2']
         """
         slaves = self._read_sysfs('/sys/class/net/{}/bonding/slaves'
                                   .format(self._ifname))
         return list(map(str, slaves.split()))
 
 
     def set_primary(self, interface):
         """
         A string (eth0, eth2, etc) specifying which slave is the primary
         device. The specified device will always be the active slave while it
         is available. Only when the primary is off-line will alternate devices
         be used. This is useful when one slave is preferred over another, e.g.,
         when one slave has higher throughput than another.
 
         The primary option is only valid for active-backup, balance-tlb and
         balance-alb mode.
 
         Example:
         >>> from vyos.ifconfig import BondIf
         >>> BondIf('bond0').set_primary('eth2')
         """
         if not interface:
             # reset primary interface
             interface = '\0'
 
         return self._write_sysfs('/sys/class/net/{}/bonding/primary'
                                  .format(self._ifname), interface)
 
     def set_mode(self, mode):
         """
         Specifies one of the bonding policies. The default is balance-rr
         (round robin).
 
         Possible values are: balance-rr, active-backup, balance-xor,
         broadcast, 802.3ad, balance-tlb, balance-alb
 
         NOTE: the bonding mode can not be changed when the bond itself has
         slaves
 
         Example:
         >>> from vyos.ifconfig import BondIf
         >>> BondIf('bond0').set_mode('802.3ad')
         """
         if not mode in [
             'balance-rr', 'active-backup', 'balance-xor', 'broadcast',
                         '802.3ad', 'balance-tlb', 'balance-alb']:
             raise ValueError("Value out of range")
 
         return self._write_sysfs('/sys/class/net/{}/bonding/mode'
                                  .format(self._ifname), mode)
 
 
 class WireGuardIf(Interface):
     """
     Wireguard interface class, contains a comnfig dictionary since
     wireguard VPN is being comnfigured via the wg command rather than
     writing the config into a file. Otherwise if a pre-shared key is used
     (symetric enryption key), it would we exposed within multiple files.
     Currently it's only within the config.boot if the config was saved.
 
     Example:
     >>> from vyos.ifconfig import WireGuardIf as wg_if
     >>> wg_intfc = wg_if("wg01")
     >>> print (wg_intfc.wg_config)
     {'private-key': None, 'keepalive': 0, 'endpoint': None, 'port': 0,
     'allowed-ips': [], 'pubkey': None, 'fwmark': 0, 'psk': '/dev/null'}
     >>> wg_intfc.wg_config['keepalive'] = 100
     >>> print (wg_intfc.wg_config)
     {'private-key': None, 'keepalive': 100, 'endpoint': None, 'port': 0,
     'allowed-ips': [], 'pubkey': None, 'fwmark': 0, 'psk': '/dev/null'}
     """
 
     def __init__(self, ifname):
         super().__init__(ifname, type='wireguard')
 
         self.config = {
             'port': 0,
             'private-key': None,
             'pubkey': None,
             'psk': '/dev/null',
             'allowed-ips': [],
             'fwmark': 0x00,
             'endpoint': None,
             'keepalive': 0
         }
 
     def update(self):
         if not self.config['private-key']:
             raise ValueError("private key required")
         else:
             # fmask permission check?
             pass
 
         cmd = "wg set {} ".format(self._ifname)
         cmd += "listen-port {} ".format(self.config['port'])
         cmd += "fwmark {} ".format(str(self.config['fwmark']))
         cmd += "private-key {} ".format(self.config['private-key'])
         cmd += "peer {} ".format(self.config['pubkey'])
         cmd += " preshared-key {} ".format(self.config['psk'])
         cmd += " allowed-ips "
         for aip in self.config['allowed-ips']:
             if aip != self.config['allowed-ips'][-1]:
                 cmd += aip + ","
             else:
                 cmd += aip
         if self.config['endpoint']:
             cmd += " endpoint {}".format(self.config['endpoint'])
         cmd += " persistent-keepalive {}".format(self.config['keepalive'])
 
         self._cmd(cmd)
 
         # remove psk since it isn't required anymore and is saved in the cli
         # config only !!
         if self.config['psk'] != '/dev/null':
             if os.path.exists(self.config['psk']):
                 os.remove(self.config['psk'])
 
 
     def remove_peer(self, peerkey):
         """
         Remove a peer of an interface, peers are identified by their public key.
         Giving it a readable name is a vyos feature, to remove a peer the pubkey
         and the interface is needed, to remove the entry.
         """
         cmd = "wg set {0} peer {1} remove".format(
             self._ifname, str(peerkey))
         return self._cmd(cmd)
 
 
 class VXLANIf(Interface, ):
     """
     The VXLAN protocol is a tunnelling protocol designed to solve the
     problem of limited VLAN IDs (4096) in IEEE 802.1q.  With VXLAN the
     size of the identifier is expanded to 24 bits (16777216).
 
     VXLAN is described by IETF RFC 7348, and has been implemented by a
     number of vendors.  The protocol runs over UDP using a single
     destination port.  This document describes the Linux kernel tunnel
     device, there is also a separate implementation of VXLAN for
     Openvswitch.
 
     Unlike most tunnels, a VXLAN is a 1 to N network, not just point to
     point. A VXLAN device can learn the IP address of the other endpoint
     either dynamically in a manner similar to a learning bridge, or make
     use of statically-configured forwarding entries.
 
     For more information please refer to:
     https://www.kernel.org/doc/Documentation/networking/vxlan.txt
     """
     def __init__(self, ifname, config=''):
         if config:
             self._ifname = ifname
 
             if not os.path.exists('/sys/class/net/{}'.format(self._ifname)):
                 # we assume that by default a multicast interface is created
                 group = 'group {}'.format(config['group'])
 
                 # if remote host is specified we ignore the multicast address
                 if config['remote']:
                     group = 'remote {}'.format(config['remote'])
 
                 # an underlay device is not always specified
                 dev = ''
                 if config['dev']:
                     dev = 'dev {}'.format(config['dev'])
 
                 cmd = 'ip link add {intf} type vxlan id {vni} {grp_rem} {dev} dstport {port}' \
                        .format(intf=self._ifname, vni=config['vni'], grp_rem=group, dev=dev, port=config['port'])
                 self._cmd(cmd)
 
         super().__init__(ifname, type='vxlan')
 
     @staticmethod
     def get_config():
         """
         VXLAN interfaces require a configuration when they are added using
         iproute2. This static method will provide the configuration dictionary
         used by this class.
 
         Example:
         >> dict = VXLANIf().get_config()
         """
         config = {
             'vni': 0,
             'dev': '',
             'group': '',
             'port': 8472, # The Linux implementation of VXLAN pre-dates
                           # the IANA's selection of a standard destination port
             'remote': ''
         }
         return config