ZyXEL Communications Corporation G210H Manuel D’Utilisation

ZyXEL G-210H User’s Guide

Appendix C

65

This section discusses some popular authentication types: EAP-MD5, EAP-TLS, EAP-TTLS, 
PEAP and LEAP. Your wireless LAN device may not support all authentication types. 

EAP (Extensible Authentication Protocol) is an authentication protocol that runs on top of the 
IEEE 802.1x transport mechanism in order to support multiple types of user authentication. By 
using EAP to interact with an EAP-compatible RADIUS server, an access point helps a 
wireless station and a RADIUS server perform authentication. 

The type of authentication you use depends on the RADIUS server and an intermediary AP(s) 
that supports IEEE 802.1x.

For EAP-TLS authentication type, you must first have a wired connection to the network and 
obtain the certificate(s) from a certificate authority (CA). A certificate (also called digital IDs) 
can be used to authenticate users and a CA issues certificates and guarantees the identity of 
each certificate owner.

MD5 authentication is the simplest one-way authentication method. The authentication server 
sends a challenge to the wireless station. The wireless station ‘proves’ that it knows the 
password by encrypting the password with the challenge and sends back the information. 
Password is not sent in plain text. 

However, MD5 authentication has some weaknesses. Since the authentication server needs to 
get the plaintext passwords, the passwords must be stored. Thus someone other than the 
authentication server may access the password file. In addition, it is possible to impersonate an 
authentication server as MD5 authentication method does not perform mutual authentication. 
Finally, MD5 authentication method does not support data encryption with dynamic session 
key. You must configure WEP encryption keys for data encryption.