new_contents: def start(context, log, args):
      import time
  
      duration = args['duration']
      period = 20
  
      n9k1_ip, n9k2_ip, _, _ = context.n9k_creds()
      log.info('Blocking N9K IPs ({0},{1}) on controllers ...'.format(n9k1_ip, n9k2_ip))
  
      start_time = time.time()
      for controller in context.controllers():
          controller.run(command='iptables -A OUTPUT -d {0}/32 -j DROP'.format(n9k1_ip))
          controller.run(command='iptables -A OUTPUT -d {0}/32 -j DROP'.format(n9k2_ip))
      while start_time + duration > time.time():
          log.info('N9K IPs are blocked.')
          time.sleep(period)
  
      log.info('Unblocking N9K IPs ({0},{1}) on controllers ...'.format(n9k1_ip, n9k2_ip))
      for controller in context.controllers():
          controller.run(command='iptables -D OUTPUT -d {0}/32 -j DROP'.format(n9k1_ip))
          controller.run(command='iptables -D OUTPUT -d {0}/32 -j DROP'.format(n9k2_ip))
  
subject: Add n9k IP iptables block