In the automotive industry, Ethernet is being used as a vehicle communication network in order to increase the speed and data bandwidth of the vehicle network. Due to the characteristic of the disclosed protocol, Ethernet can be easily applied to various industrial fields. Also,since it is a standard specification based on open protocol, there aresome advantages, such as the compatibility between existing functions and other industrial fields. In recent years, automotive operating systems such as AUTOSAR have also supported Ethernet as a vehicle communication network. This is because functions such as advanced driver assistance system (ADAS) and around view monitoring system (AVMS) in vehicles require large data transfer and speed. It is also used to diagnose the vehicle remotely using Ethernet and to provide diagnostic information to a driver. However, the characteristic of the disclosed protocol causes Ethernet to be vulnerable to the security issues. Therefore, to ensure the safety of the vehicle and the driver, the enhanced method for the security and controlling access to the Ethernet is imperative. In this paper, we propose a security and authentication protocol based on IPSec that encrypts the diagnostic information of the vehicle. With this security protocol, we can encrypt and authenticate diagnosis information of the vehicle on Ethernet. Therefore, the safety level of the vehicle can be enhanced.And,it will prevent to access diagnosis information from unauthorized user.