Hi,
the easiest way - use different server/message types for different ports.
for example - usual HTTP should be used for normal port and ,say, SuperTCP for maintenance one or Bin message for normal users and another message type for maintenance.
in this way with GetDispatchInfo event you can distinguish what server/message was used.
another way: add roles.
You can assign maintenance role to MaintenanceService and users who don’t have this role can’t access to this server.
Role for users can be set in Login method.
Roles for Services/methods can be set in ServiceBuilder for RODL-based services or via RORole attribute for Code-First based services.