PPP：
单向认证：
PAP：
主认证方：
[R1]local-user R2 class network
New local user added.
[R1-luser-network-R2]password simple 123
[R1-luser-network-R2]service-type ppp
[R1-luser-network-R2]quit
[R1]int s1/0
[R1-Serial1/0]ppp authentication-mode pap
被认证方：
[R2]int s1/0
[R2-Serial1/0]ppp pap local-user R2 password simple 123
CHAP:
主认证方：
[R1]int s1/0
[R1-Serial1/0]ppp authentication-mode chap
[R1-Serial1/0]ppp chap user R1
[R1-Serial1/0]quit
[R1]local-user R2 class network
[R1-luser-network-R2]password simple 123
[R1-luser-network-R2]service-type ppp
被认证方：
[R2]int s1/0
[R2-Serial1/0]ppp chap user R2
[R2-Serial1/0]ppp chap password simple 123
双向认证：
PAP：
R1配置
[R1]local-user R2 class network
New local user added.
[R1-luser-network-R2]password simple 123
[R1-luser-network-R2]service-type ppp
[R1-luser-network-R2]quit
[R1]int s1/0
[R1-Serial1/0]link-protocol ppp
[R1-Serial1/0]ppp authentication-mode pap
[R1-Serial1/0]ppp pap local-user R1 password simple 123
R2配置
[R1]local-user R1 class network
New local user added.
[R1-luser-network-R2]password simple 123
[R1-luser-network-R2]service-type ppp
[R1-luser-network-R2]quit
[R1]int s1/0
[R1-Serial1/0]link-protocol ppp
[R1-Serial1/0]ppp authentication-mode pap
[R1-Serial1/0]ppp pap local-user R2 password simple 123
CHAP:
R1配置
[R1]local-user R2 class network
[R1-luser-network-R2]service-type ppp
[R1-luser-network-R2]password simple 123
[R1-luser-network-R2]quit
[R1]int s1/0
[R1-Serial1/0]ppp authentication-mode chap
[R1-Serial1/0]ppp chap user R1
[R1-Serial1/0]ppp chap password simple 123
R2配置
[R2]local-user R1 class network
[R2-luser-network-R1]service-type ppp
[R2-luser-network-R1]password simple 123
[R2-luser-network-R1]quit
[R2]int s1/0
[R2-Serial1/0]ppp authentication-mode chap
[R2-Serial1/0]ppp chap user R2
[R2-Serial1/0]ppp chap password simple 123
原文：http://llzzgg.blog.51cto.com/10535395/1762447