title: Passive Monitoring with Nagios / Icinga - How to monitor external hosts correctly?
body: <p>Good morning,</p>
  
  <p>Our goal is to monitor many external clients with a open source monitoring solution like Icinga or Nagios.. </p>
  
  <p>Because most of our customers have multiple devices but only one dynamic public IP, we are still looking for one solution which works for all of our clients. The amount of clients and networks is too high that we can use VPN to connect them with Icinga. It would fit if all clients send their check reports to the icinga host. Many other monitoring solutions, such as GFI MAX simply let the clients report through TCP 443 or TCP 80 (failover). If an interval has been interrupted, the monitoring server will mark the client with a critical failure.</p>
  
  <p>Here some more information about our internal infrastructure:
  - Icinga Core 1.11.1 / Nagios
  - static IP for monitoring server
  - Endian Firewall</p>
  
  <p>At the client side:
  - Windows devices with NSClient++
  - no static IP
  - NAT and firewall are configurable</p>
  
  <p>Based on my information can you suggest a solution to let the clients send their information to the Icinga server, please? Besides is it even possible to realize this scenario without VPN, static IP or dynamic dns?</p>
  
  <p>THank you for helping me out!</p>