  IEEE 802.1X is an international standard for Port-based Network Access
Control which provides authentication for devices applicant of either local
network or wireless local network. This standard defines the packing of EAP
protocol on IEEE 802. In this standard, authentication protocols become a
complementary part of network security. There is a variety in EAP family
protocols, regarding their speed and security. One of the fastest of these
protocols is EAP-MD5 which is the main subject of this paper. Moreover, in
order to improve EAP-MD5 security, a series of attacks against it have been
investigated. In this paper at first EAP-MD5 protocol is introduced briefly and
a series of the dictionary attacks against it are described. Then, based on
observed weaknesses, by proposing an appropriate idea while maintaining the
speed of execution, its security against dictionary attack is improved.
