CLI Reference Guide-R07

Chapter 8 | Authentication Commands
Secure Shell
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6. Authentication – One of the following authentication methods is employed:
Password Authentication (for SSH V2 Clients)
a. The client sends its password to the server.
b. The switch compares the client's password to those stored in memory.
c. If a match is found, the connection is allowed.
Note: To use SSH with only password authentication, the host public key must still
be given to the client, either during initial connection or manually entered into the
known host file. However, you do not need to configure the client's keys.
Public Key Authentication – When an SSH client attempts to contact the switch,
the SSH server uses the host key pair to negotiate a session key and encryption
method. Only clients that have a private key corresponding to the public keys
stored on the switch can access it. The following exchanges take place during
this process:
Authenticating SSH v2 Clients
a. The client first queries the switch to determine if public key
authentication using a preferred algorithm is acceptable.
b. If the specified algorithm is supported by the switch, it notifies the
client to proceed with the authentication process. Otherwise, it
rejects the request.
c. The client sends a signature generated using the private key to the
switch.
d. When the server receives this message, it checks whether the
supplied key is acceptable for authentication, and if so, it then checks
whether the signature is correct. If both checks succeed, the client is
authenticated.
Note: The SSH server supports up to eight client sessions. The maximum number
of client sessions includes both current Telnet sessions and SSH sessions.
Note: The SSH server can be accessed using any configured IPv4 or IPv6 interface
address on the switch.
ip ssh
authentication-retries
This command configures the number of times the SSH server attempts to
reauthenticate a user. Use the no form to restore the default setting.
Syntax
ip ssh authentication-retries count
no ip ssh authentication-retries