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Session request, Data exchange, Ssh server and client configuration task list – H3C Technologies H3C S3100 Series Switches User Manual

Page 717: Configuring the ssh server

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In password authentication, the client encrypts the username and password, encapsulates them

into a password authentication request, and sends the request to the server. Upon receiving the

request, the server decrypts the username and password, compares them with those it maintains,

and then informs the client of the authentication result.

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The publickey authentication method authenticates clients using digital signatures. Currently, the

device supports two publickey algorithms to implement digital signatures: RSA and DSA. The client

sends to the server a publickey authentication request containing its user name, public key and

algorithm. The server verifies the public key. If the public key is invalid, the authentication fails;

otherwise, the server generates a digital signature to authenticate the client, and then sends back a

message to inform the success or failure of the authentication. 

Session request

After passing authentication, the client sends a session request to the server, while the server listens to

and processes the request from the client. If the client passes authentication, the server sends back to

the client an SSH_SMSG_SUCCESS packet and goes on to the interactive session stage with the

client. Otherwise, the server sends back to the client an SSH_SMSG_FAILURE packet, indicating that

the processing fails or it cannot resolve the request. The client sends a session request to the server,

which processes the request and establishes a session.

Data exchange

In this stage, the server and the client exchanges data in this way:

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The client encrypts and sends the command to be executed to the server.

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The server decrypts and executes the command, and then encrypts and sends the result to the

client.

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The client decrypts and displays the result on the terminal.

SSH Server and Client Configuration Task List

Many devices can act as the SSH server and client. This document describes two cases:

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The H3C switch acts as the SSH server to cooperate with software that supports the SSH client

functions.

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The H3C switch acts as the SSH server to cooperate with another H3C switch that acts as an SSH

client.

Complete the following tasks to configure the SSH server and clients:

Server

Client

Server side

configuration

Client side configuration

An H3C switch

Software that
supports the SSH
client functions

Configuring the SSH
Server

Configuring an SSH Client that
Runs SSH Client Software

An H3C switch

Another H3C switch

Configuring the SSH
Server

Configuring an SSH Client
Assumed by an
SSH2-Capable Switch

Configuring the SSH Server

The session establishment between an SSH client and the SSH server involves five stages. Similarly,

SSH server configuration involves five aspects, as shown in the following table.