Currently, the dual use of IPv4 and IPv6 is becoming a problem. In particular, Network Address Translation (NAT) is an important issue to be solved because of traversal problems in end-to-end applications for lots of mobile IoT devices connected to different private networks. The vertical model is typically used to solve NAT, mobility and security issues for them. However, the existing vertical model has limitations because it handles NAT, mobility and security management one by one. This paper proposes a Blockchain-based Integrated Network Function Management (BINFM) scheme where the NAT, mobility, and security management are handled at once. The proposed scheme is advantageous in that by using blockchain and the Query/Reply mechanism, each peer can easily obtain the necessary parameters required to handle the NAT, mobility, and security management in a batch. In addition, this paper explains how our proposed scheme guarantees secure end-to-end data transfers with the use of one time session key. Finally, it is proved that the proposed scheme improves performance on latency from the viewpoints of mobility and security compared to the existing vertical model. mobile IoT devices connected to private networks in the smart city on the condition that a smart mobility management is provided [10][11][12].In recent decades, preserving privacy and ensuring the security of data have emerged as important issues as confidential information or private data may be revealed by powerful data mining tools [13][14][15]. Therefore, if hackers attack a smart city with lots of IoT devices, the outcome could be far more catastrophic. It is argued that IPv6 offers better security solutions than IPv4, largely due to IPSec, with which IPv6 operates. It is known that widespread adoption of IPv6 will make man-in-the-middle attacks significantly more difficult [16]. IPSec, which works on a layer 3 plane, i.e., the network layer, aims to provide application-layer security in batch by means of securing IP-layer. However, it poses a difficult problem to run end-to-end encryption because of its difficult key exchange protocol between end-to-end IoT peers [17]. Small IoT end points will face a burden when they handles security association data to secure the layer 3 datagram services. So this paper is based on the idea that IPSec is difficult to be realized for mobile IoT devices with the private IP addresses.As depicted in Figure 1, the existing vertical model starts with the NAT management followed by mobility management. Once the NAT and mobility management are made, the security management procedure begins.Static assignment of IP addresses gives adversaries significant advantage to remotely scan networks and identify their targets accurately and quickly. As traditional approaches against this attack, the IP address assignment scheme based on DHCP or NAT has been used. However, they are insufficient to provide proactive countermeasures because the IP mutation is infrequent and traceable. Recently, OpenFlow Random Host Mutation (OFRHM), in whi...