Interact with PF

PF is the macOS built-in packet filter. It is a network firewall, it filters connections at network level. Murus is a GUI front end for PF. Murus and Vallum are designed to interact.
To enable Murus interaction in Vallum you need to activate it in Vallum Preferences -> General.

Vallum Notification alert allows you to create filtering rule at network level. These rules are system wide and affect all apps. This feature requires Murus Basic or Murus Pro to be installed, configured and running. You can add one or more custom rules or put current IP address in Murus black list or in a new or existing Murus group.
If you have Murus correctly configured then Vallum notification alerts will display the list of services that contain the port involved in current connection. Select a service to manage or unmanage it in Murus Managed Outbound Services.