How can I limit the connections to my system on host level?

In default every machine has the permission to establish a connection to your system. It is possible to limit the amount of hosts to a specific list with the usage of 2 config entries: „ip_deny“ and „ip_allow“

Example:
[general]
ip_deny = "*"
ip_allow = "127.0.0.1"
ip_allow = "192.168.128.10"
ip_allow = "192.168.128.11"

With this setting all connection attempts except 192.168.128.10 and 192.168.128.11 are denied by the WinCC OA Server.