Knock Knock Server Free

You can easily check the server monitor.
If an error occurs on the server you're managing, you can easily see from the terminal Android.

Restriction:
- You're using your ISP or Telecommunications Carrier, because the port is not allowed to connect, you may be able to connect to arbitrary ports.
- That security software is installed on Android devices If you could not connect.
- The configuration changes that you are using your ISP or Telecommunications Carrier, you may be able to connect to the port.

Restriction of Free version:
The connecting server is to three.