How to solve the problem when one computer is always unable to connect when connecting to ssh in linux

The solutions to the problem that Linux cannot connect to a machine when connecting to SSH are: 1. Check whether the IP address, network configuration and firewall settings of the target host are correct; 2. Confirm whether the SSH service on the target host is running; 3. Check the firewall settings on the target host; 4. Check whether the SSH configuration file on the target host is correct; 5. If using an SSH key for authentication, ensure that the public key has been correctly added to the target host; 6. Try adding -v Parameters to start an SSH connection to view detailed connection debugging information.

The operating system of this tutorial: Linux5.18.14 system, Dell G3 computer.

When you encounter a situation where a computer cannot be connected when connecting to Linux SSH, you can try the following steps to solve the problem:

1. Network connection check:

Make sure that the target Linux host and your computer are in the same network, and the network connection is normal. Check that the target host's IP address, network configuration, and firewall settings are correct.

2. SSH service status:

Confirm whether the SSH service on the target Linux host is running. You can use the following command to check the SSH service status:

  service ssh status

If the SSH service is not running, you can use the following command to start the SSH service (root permissions are required):

  service ssh start

3. Target host firewall :

Check the firewall settings on the target host to ensure that the port for the SSH service (default is 22) is not blocked. You can try turning off the firewall or adding corresponding rules to allow SSH connections.

4. SSH configuration file:

Check the SSH configuration file on the target host to confirm whether the relevant configuration of the SSH service is correct. The configuration file is usually located at /etc/ssh/sshd_config. You can use a text editor to open and check related configuration items.

5. SSH key authentication:

If you use SSH key for authentication, please make sure that your public key has been correctly added to the target host’s ~/. ssh/authorized_keys file. You can use the following command to add the public key to the authorized_keys file of the target host:

  ssh-copy-id username@target_host

Replace username with your username and target_host with the IP address or domain name of the target host.

6. SSH parameter debugging:

Try to start the SSH connection by adding the -v parameter to view detailed connection debugging information. For example:

  ssh -v username@target_host

This will output detailed information during the connection process, which can help you determine the specific reason for the connection failure.

If you still cannot solve the connection problem, it is recommended to check the system log of the target host (such as /var/log/messages or /var/log/auth.log) for more error information. Also, if possible, try an SSH connection from another computer to verify if the issue is with a specific computer.

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