The present invention relates to a method, by a target node classification entity (100), to control an application of a service providing module (50) to a data packet flow, wherein the data packet flow is transmitted to a target node (310, 320) through a service network where the service providing module (50) applies a service to the data packet flow. The method comprises the following steps: First, from a flow classification entity (40), flow classification data about the data packet flow is received, the flow classification data including at least a flow classifier classifying the data packet flow, a flow identifier uniquely identifying the data packet flow, and a target node address to which the data packet flow is addressed. Then, the target node is classified based on the flow classifier contained in the received flow classification data, wherein a first service classifier is generated for the target node based on the flow classifier. Then, it is checked whether a classification database (120) has to be updated based on the first classifier of the target node, the classification database storing, for different target nodes, whether at least one service has to be applied to data packet flows to the corresponding target node. Furthermore, if the information in the classification database has to be updated, a flow command is generated for a central flow controller (200) which controls the data packet flows through the service network, wherein the generated flow command contains the information that successive data packet flows in the service network transmitted to the target node address should be passed through the service network in accordance with the generated first service classifier of the target node, and the generated flow command is transmitted to the central flow controller (200).