diff --git a/README.md b/README.md
index 67e3024..0194b78 100644
--- a/README.md
+++ b/README.md
@@ -18,6 +18,8 @@ MAC addresses are used to rename interfaces in the host OS. Prefix for the manag
 
 For Windows hosts the platform must be defined in NetBox to configure connection parameters.
 
+All inbound traffic to devices and VMs is dropped by default. To allow requests to one or more ports for a device or VM, define in NetBox appropriate services with the custom fields `allowed_{ips,prefixes,vlans,clusters}`. If no limits are given, the service is open to everyone.
+
 ## Run
 
 Create a read-only token in NetBox. Define required variables: