Public network protocol is generally used in network, but some special users, with special consideration, do not trust the safety of the public protocol. It needs customized proprietary protocols, to meet the needs of security and particularity. A proprietary protocols is designed based on CIPSO standard transformation, to realize the existing normal communication under the network environment, and meet other specific information requirements according to the security level to control the data flow. To avoid conflicts due to the similarity by the protocol, the concept of anti-conflict flag is proposed and the anti-conflict negotiation mechanism is designed. With the method of transplantation LWIP stack, the proprietary protocol is implemented.