SMC Networks TigerAccess SMC7816M - Manual (Page 160)

U
SER
A
UTHENTICATION
6-12
6. Authentication – One of the following authentication methods is
employed:
Password Authentication (for SSH v1.5 or 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 v1.5 Clients
a. The client sends its RSA public key to the switch.
b. The switch compares the client's public key to those stored in
memory.
c. If a match is found, the switch uses its secret key to generate a
random 256-bit string as a challenge, encrypts this string with the
user’s public key, and sends it to the client.
d. The client uses its private key to decrypt the challenge string,
computes the MD5 checksum, and sends the checksum back to the
switch.
e. The switch compares the checksum sent from the client against that
computed for the original string it sent. If the two checksums
match, this means that the client's private key corresponds to an
authorized public key, and the client is authenticated.