Fedora39 ; SSH 、Firewalld

1.Remote connection by SSH

SSH is a service for connecting remotely to a server, basically running immediately after OS installation, but the default settings are somewhat insecure.
Configure the default settings to increase the security of ssh connections.

1.1 SSH service configuration file changes

The SSH service configuration file is "/etc/ssh/sshd_config".
Open the configuration file in a vi editor.

sshd.service restart

If this is not done, the next time you reboot, you will not be able to connect remotely via SSH. Please free SSH port 2244 in the following firewall settings.

2.Firewall (firewalld) settings

In Fedora, firewalld is set as the default and is enabled during OS installation.

2.1 How to use the "firewall-cmd" command to control "firewalld

1. Command to check the status and settings of "firewalld

    ①Check firewalld operation status

    If "firewalld" is running, the message "running" will be displayed; if it is not running, the message "not running" will be displayed.


    ※When stopped
    Active: inactive (dead) is displayed, indicating that firewalld is stopped

    View default zone setting

    In the above example, we can see that the services "cockpit", "dhcpv6-client", "ntp", "ssh" are allowed, etc.

    About the "--permanent" option
    To prevent the settings from disappearing when the server is restarted or the "firewalld" service is restarted, the
    The "--permanent" option must be used to configure the settings.
    If the "--permanent" option is specified, it is necessary to use "fiewall-cmd --reload" to reflect the settings, as they are not reflected in "firewalld" as they are.

    Permanent use of HTTP service without initialization after system reboot

    How to start/stop
    Since "firewalld" is controlled by "systemd", use the "systemctl" command to start and stop it.

    2.2   Release modified SSH port 2244

    3.Remote connection from Windows

    Settings Windows
    The terminal emulator is "Tera Term".
    Start Tera Term, cancel the startup screen, and then select "New Connection" from "File" in the Tera Term menu.

    Enter your own settings in the "Server IP address" and "TCP port number" fields.
    Finally, click "OK

    After clicking "OK," click "Continue" on the security confirmation screen.
    Enter "User name" "Passphrasee" and click "OK".

    If the information is correct, you should be able to log in successfully.

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