Icinga add custom service without adding hosts

I use servername.conf (for hosts), and services.conf for all servcies. But now, I want check only services in ipfire server, but I dont want check/ping gateway server/ host connectivity from master node because ipfire server rejected connectivity. So I use this code:

apply Service "pakfire" {
  import "1day-service"
  check_command = "pakfire_status"
  assign where ???

But what code used to the assign where command? Because I dont want to connect host, so not good match “something”, host.display_name.

The pakfire_status contains all important data for connect server, and running command.

You always need some host to attach a service!
It’s no problem to use one or more dummy hosts - use dummy check as host check.
You could also use the most basic/robust of your ipfire checks as host check.
Also you probably need to set the host that the checks has to run on, if there isn’t a agent on the target. Search for command_endpoint.