H3C S5830V2 Security Configuration Manual page 22

Figure 6 Basic HWTACACS packet exchange process for a Telnet user
Host
1) The user tries to log in
4) Request for username
5) The user enters the username
8) Request for password
9) The user enters the password
14) The user logs in successfully
17) The user logs off
HWTACACS operates in the following manner:
1. A Telnet user sends an access request to the HWTACACS client.
2. Upon receiving the request, the HWTACACS client sends a start-authentication packet to the
HWTACACS server.
3. The HWTACACS server sends back an authentication response to request the username.
4. Upon receiving the response, the HWTACACS client asks the user for the username.
5. The user enters the username.
6. After receiving the username from the user, the HWTACACS client sends the server a
continue-authentication packet that includes the username.
7. The HWTACACS server sends back an authentication response, requesting the login password.
8. Upon receipt of the response, the HWTACACS client asks the user for the login password.
HWTACACS client
2) Start-authentication packet
3) Authentication response requesting the username
6) Continue-authentication packet with the username
7) Authentication response requesting the password
10) Continue-authentication packet with the password
11) Response indicating successful authentication
12) User authorization request packet
13) Response indicating successful authorization
15) Start-accounting request
16) Response indicating the start of accounting
18) Stop-accounting request
19) Stop-accounting response
8
HWTACACS server