In access technologies for network security

the IEEE 802.1xprotocol-based authentication method is much superior to other authentication technologies

but it still has some deficiencies in practice.This paper briefly describes the protocol security

analyzes the existing security defects and presents an improvement process and solutions.It effectively avoids the middleman attack and Denial of Service（DoS）attack by improving the Type-Data domain in the messages in the protocol packets.The results show that although the improved protocol may lead to slight increase of the switch CPU utilization rate

it still can reach the filtration rate of as high as 86.3%in large numbers of message attacks.