NAT Issues in the Remote Management of Home Network Devices

Currently, many customer devices are being connected to home networks. For this reason, it is expected that device management capabilities will be a powerful instrument for the service provider to cope with high maintenance costs, security concerns, and management issues related to home networks. Through DM, the service provider could provide valuable services such as auto-provisioning, remote configuration, firmware and software updates, diagnostics, monitoring, scheduling, and fraud management. However, network address translators that are widely deployed in the home network environment prohibit DM operations from reaching user devices behind the NAT. In this article, we focus on NAT issues in the management of home network devices. Specifically, we discuss efforts relating to standardization and present our proposal to deploy DM services for VoIP and IPTV devices behind NATs. By slightly changing the behavior of Simple Network Management Protocol managers and agents and by defining additional management objects (MOs) to gather NAT binding information, we could solve the NAT traversal problem under a symmetric NAT. Moreover, we propose an enhanced method to search for the UDP hole binding time of the NAT box. For evaluation, we applied our method to 22 randomly selected VoIP devices out of 194 NATed hosts in the real broadband network and achieved a success ratio of 99 percent for exchanging SNMP request messages and a 26 percent enhancement in determining the UDP hole binding time.