Principles of the router PPP authentication protocol !!

PPP, that is, the Point-to-Point Protocol, is the data link layer protocol for point-to-point lines launched by IETF. This protocol is not a proprietary protocol. It can connect devices of different vendors, support multiple protocols, provide optional authentication services, compress data in various ways, support dynamic address negotiation, and support multi-link bundling.

1. PAP:

Password Authentication Protocol, full name: Password Authentication Protocol. PAP is a two-way handshake authentication protocol. When the link is initialized for the first time, the authenticated end first initiates an authentication request and sends the user name and password information to the authenticated end for identity authentication. The password and password are sent in plain text, so the security is low. PAP supports single-and two-way authentication, authentication flowchart and single-and two-way authentication.

Ii. CHAP:

Challenge Handshake Authentication Protocol, full name: Challenge Handshake Authentication Protocol. CHAP verifies the identity of the authenticated end through a three-way handshake. It is completed when the initial link is established. To improve security, it is periodically verified after the link is established. CHAP is safer than PAP because CHAP does not send plain text online, but instead sends a random number sequence that has passed MD5. CHAP supports one-way and two-way authentication.

Iii. configuration process:

Hostname R_A

Interface serial/0

Ip address 192.168.1.1 255.255.255.0

Encapsulation ppp

Ppp pap sent-username R_A password 0 123

Clock rate 64000

R_A (config-if) # ip address 192.168.1.1 255.255.255.0

R_A (config-if) # no shutdown

% LINK-5-CHANGED: Interface serial/0, changed state to up

Router> en

Router # conf t

Enter configuration commands, one per line. End with CNTL/Z.

Router (config) # hostname R_ B

R_ B (config) # username R_A password 0 123

R_ B (config) # interface s3/0

R_ B (config-if) # encapsulation ppp

R_ B (config-if) # ppp authentication pap

R_ B (config-if) # ip address 192.168.1.2 255.255.255.0

R_ B (config-if) # no shutdown

On router R_A:

R_A # debug ppp authentication

PPP authentication debugging is on

Serial/0 Using hostname from interface PAP

Serial/0 Using password from interface PAP

Serial/0 PAP: O AUTH-REQ id 17 len 15

Serial/0 PAP: Phase is FORWARDING, Attempting Forward

% LINEPROTO-5-UPDOWN: Line protocol on Interface serial/0, changed state to up

On router R_ B:

R_ B # ping 192.168.1.1

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 192.168.1.1, timeout is 2 seconds:

Success rate is 100 percent (5/5), round-trip min/avg/max = 2/4/6 MS

At last, pay attention to the correspondence between the user name and password information and the vro; the correspondence between the authentication end and the authenticated end; the authentication information is case sensitive; if the configuration is not effective after modification, try to restart the port.