Some embodiments provide a method for configuring a gateway machine in a datacenter. The method receives a definition of a logical network for implementation in the datacenter. The logical network includes at least one logical switch to which logical network endpoints attach and a logical router for handling data traffic between the logical network endpoints in the datacenter and an external network. The method receives configuration data attaching a third-party service to at least one interface of the logical router via an additional logical switch designated for service attachments. The third-party service is for performing non-forwarding processing on the data traffic between the logical network endpoints and the external network. The method configures the gateway machine in the datacenter to implement the logical router and redirect at least a subset of the data traffic between the logical network endpoints and the external network to the attached third-party service.