A relay server includes a VPN group information storage unit, an address filter information storage unit, and a communication control unit. The VPN group information storage unit stores routing session information indicating identification information of routing apparatuses that define a VPN group and the routing apparatuses that are connected to one another. The address filter information storage unit stores address filter information, which indicates a partner that the routing apparatus is able to designate as a packet destination, in association with identification information of the routing apparatus. The communication control unit is programmed to perform a control to, when a VPN is started in the VPN group, update a content stored in the address filter information storage unit based on the address filter information received from the routing apparatus, and establish a routing session based on the routing session information.