Cu ently, the switch supports only SSH2 Version.
rr
Versi
z
he first packet to the client, which includes a version identification string in the
ile the software version number is used for debugging.
on of the server; otherwise, the client uses its own
protocol version.
nt sends to the server a packet that contains the number of the protocol version it decides
e server compares the version carried in the packet with that of its own to determine
wheth
n cooperate with the client.
he client go on to the key and algorithm negotiation.
If not, the server breaks the TCP connection.
on negotiation
z
The server opens port 22 to listen to connection requests from clients.
The client sends a TCP connection request to the server. After the TCP connection is established,
the server sends t
format of “SSH-<primary protocol version number>.<secondary protocol version
number>-<software version number>”. The primary and secondary protocol version numbers
constitute the protocol version number, wh
z
The client receives and resolves the packet. If the protocol version of the server is lower but
supportable, the client uses the protocol versi
z
The clie
to use. Th
er it ca
z
If the negotiation is successful, the server and t
All the packets above are transferred
in plain text.
Key n
er and the client, encrypted algorithm list, message
) algorithm list, and compressed algorithm list.
culate the final algorithm according to the algorithm lists supported.
the session key and session ID based on the Diffie-Hellman (DH)
z
A
e
The
n steps are as follows:
ns
the password.
ion
failure message to the client, which contains the list of methods used for a new authentication
process.
egotiation
z
The server and the client send algorithm negotiation packets to each other, which contain public
key algorithm lists supported by the serv
authentication code (MAC
z
The server and the client cal
z
The server and the client generate
exchange algorithm and the host key pair.
Then, the server and the client get the same session key and use it for data encryption and
decryption to secure data communication.
uth ntication negotiation
negotiatio
z
The client sends an authentication request to the server. The authentication request contai
username, authentication type, and authentication-related information. For example, if the
authentication type is
password
, the content is
z
The server starts to authenticate the user. If authentication fails, the server sends an authenticat
