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SSH is an acronym for Secure Shell and was developed by IETF's network team (Network Working Group). SSH is a security protocol based on the application layer. SSH is currently a reliable protocol designed to provide security for remote login sessions and other network services. The use of SSH protocol can effectively prevent information leakage in the process of remote management. SSH was originally a program on the UNIX system, and then rapidly expanded to other operating platforms.

1. Description of SSH login failure error message

An error occurred when the client connected to the server through the ssh protocol, as shown in the figure:

Second, error troubleshooting

First, troubleshoot whether it is a client-side problem, through the ping command and telnet troubleshooting.

The ping result is shown in the following figure:

The telnet result chart is shown in the following figure:

Both ping and telnet are connected, which means it is not the problem of the client, but the reason of the server. You need to log in to the server for troubleshooting.

Although it is not possible to ssh to the server, generally speaking, the host provides some ways for you to connect, such as connecting through a physical terminal.

After logging in to the server, check the / etc/hosts.allow file to see whether the client IP is in the whitelist. By checking, it is found that the client IP is not in the whitelist of the server. Add the client ip to the whitelist through vi / etc/hosts.allow, as shown below:

Then restart ssh, restart the command

Service sshd restart

Client re-ssh, login succeeded, problem solved.

These are the details of the solution to the failure to start ssh under linux. Please pay more attention to other related articles!

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