3Com 400 Family, Руководство по настройке

Страница: 277 / 344

SSH Terminal Services 275
authentication and RSA authentication. In the first type, the server compares
the username and password received with those configured locally. The user is
allowed to log on to the Switch if the usernames and passwords match exactly.
RSA authentication works in this way: The RSA public key of the client user is
configured at the server. The client first sends the member modules of its RSA
public key to the server, which checks its validity. If it is valid, the server
generates a random number, which is sent to the client after being encrypted
with RSA public key. Both ends calculate authentication data based on the
random number and session ID. The client sends the authentication data
calculated back to the server, which compares it with its attention data
obtained locally. If they match exactly, the user is allowed to access the Switch.
Otherwise, authentication process fails.
■
Session request stage: The client sends session request messages to the server
which processes the request messages.
■
Interactive session stage: Both ends exchange data till the session ends.
Session packets are encrypted in transfer and the session key is generated
randomly. Encryption is used in exchanging session key and RSA authentication
achieves key exchange without transfer over the network. SSH can protect
server-client data security. The authentication will also start even if the
username received is not configured at the server, so malicious intruders
cannot judge whether a username they key in exists or not. This is also a way to
protect a username.
Configuring SSH Server Basic configuration tasks refer to those required for successful connection from
SSH client to SSH server, which advanced configuration tasks are those modifying
SSH parameters.
Configuration tasks on the SSH server include:
■
Setting system protocol and link maximum
■
Configuring and deleting local RSA key pair
■
Configuring authentication type
■
Defining update interval of server key
■
Defining SSH authentication timeout value
■
Defining SSH authentication retry value
■
Entering public key view and editing public key
■
Associating public key with SSH user
Setting System Protocol You must specify SSH protocol for the system before enabling SSH.
Perform the following configuration in System View.
Table 327 Setting System Protocols and Link Maximum
By default, the system supports Telnet and SSH protocols.
Operation Command
Set system protocol and link maximum
protocol inbound { all | ssh | telnet }