Huawei Quidway S3900 Series Operation Manual page 821

Operation Manual - SSH Terminal Services
Quidway S3900 Series Ethernet Switches-Release 1510
Server Server Server Server Server Server
Figure 1-2 Establish SSH channels through WAN
The communication process between the server and client includes these five stages:
1) Version negotiation stage. These operations are completed at this stage:
The client sends TCP connection requirement to the server.
When TCP connection is established, both ends begin to negotiate the SSH
version.
If they can work together in harmony, they enter the key algorithm negotiation
stage. Otherwise the server clears the TCP connection.
2) Key algorithm negotiation stage. These operations are completed at this stage:
The server sends the public key in a randomly generated RSA key pair to the
client.
The client figures out session key based on the public key from the server and the
random number generated locally.
The client encrypts the random number with the public key from the server and
sends the result back to the server.
The server then decrypts the received data with the server private key to get the
client random number.
The server then uses the same algorithm to work out the session key based on
server public key and the returned random number.
Then both ends get the same session key without data transfer over the network, while
the key is used at both ends for encryption and decryption.
3) Authentication method negotiation stage. These operations are completed at this
stage:
The client sends its username information to the server.
Workstation Workstation Workstation Workstation
Local Switch Local Switch Local Switch Local Switch Local Switch Local Switch
Local Ethernet Local Ethernet Local Ethernet Local Ethernet Local Ethernet Local Ethernet
Laptop Laptop Laptop Laptop Laptop Laptop Laptop Laptop Laptop Laptop
PC PC PC PC PC PC
SSH-Client SSH-Client SSH-Client SSH-Client SSH-Client SSH-Client
Remote Switch Remote Switch
SSH-Server SSH-Server
Huawei Technologies Proprietary
Chapter 1 SSH Terminal Services
WAN WAN WAN WAN WAN WAN
Remote Ethernet Remote Ethernet Remote Ethernet Remote Ethernet
PC PC PC PC PC PC PC PC PC PC
1-2
Workstation Workstation Workstation Workstation
Laptop Laptop Laptop Laptop Laptop Laptop Laptop Laptop Laptop Laptop
Server Server Server Server