new_contents: #!/usr/bin/env python3
  #
  # Copyright (C) 2018 VyOS maintainers and contributors
  #
  # This program is free software; you can redistribute it and/or modify
  # it under the terms of the GNU General Public License version 2 or later as
  # published by the Free Software Foundation.
  #
  # This program 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 General Public License for more details.
  #
  # You should have received a copy of the GNU General Public License
  # along with this program.  If not, see <http://www.gnu.org/licenses/>.
  #
  
  import argparse
  
  import tabulate
  
  import vyos.config
  
  from isc_dhcp_leases import Lease, IscDhcpLeases
  
  
  lease_file = "/config/dhcpd.leases"
  pool_key = "shared-networkname"
  
  def in_pool(lease, pool):
      if pool_key in lease.sets:
          if lease.sets[pool_key] == pool:
              return True
  
      return False
  
  def get_lease_data(lease):
      data = {}
  
      # End time may not be present in backup leases
      try:
          data["expires"] = lease.end.strftime("%Y/%m/%d %H:%M:%S")
      except:
          data["expires"] = ""
  
      data["hardware_address"] = lease.ethernet
      data["hostname"] = lease.hostname
      data["ip"] = lease.ip
  
      try:
          data["pool"] = lease.sets[pool_key]
      except:
          data["pool"] = ""
  
      return data
  
  def get_leases(leases, state=None, pool=None):
      leases = IscDhcpLeases(lease_file).get()
  
      if state is not None:
          leases = list(filter(lambda x: x.binding_state == 'active', leases))
  
      if pool is not None:
          leases = list(filter(lambda x: in_pool(x, pool), leases))
  
      return list(map(get_lease_data, leases))
  
  def show_leases(leases):
      headers = ["IP address", "Hardware address", "Lease expiration", "Pool", "Client Name"]
  
      lease_list = []
      for l in leases:
          lease_list.append([l["ip"], l["hardware_address"], l["expires"], l["pool"], l["hostname"]])
  
      output = tabulate.tabulate(lease_list, headers)
      
      print(output)
  
  
  if __name__ == '__main__':
      parser = argparse.ArgumentParser()
  
      group = parser.add_mutually_exclusive_group()
      group.add_argument("-l", "--leases", action="store_true", help="Show DHCP leases")
      group.add_argument("-s", "--statistics", action="store_true", help="Show DHCP statistics")
  
      parser.add_argument("-e", "--expired", action="store_true", help="Show expired leases")
      parser.add_argument("-p", "--pool", type=str, action="store", help="Show lease for specific pool")
  
      args = parser.parse_args()
  
      if args.leases:
          if args.expired:
              if args.pool:
                  leases = get_leases(lease_file, state='free', pool=args.pool)
              else:
                  leases = get_leases(lease_file, state='free')
          else:
              if args.pool:
                  leases = get_leases(lease_file, state='active', pool=args.pool)
              else:
                  leases = get_leases(lease_file, state='active')
  
          show_leases(leases)
  
subject: add a new DHCP op mode script, only capable of showing leases now.