SSH Service Configuration: A Detailed Explanation of Linux Remote Connection
SSH is a secure remote login protocol that encrypts data transmission, used for remote management of Linux servers (such as cloud servers and local servers), replacing insecure protocols like Telnet. Key configuration steps: Install `sshd` on the server (using `apt` for Debian/Ubuntu, `yum` for CentOS/RHEL), start it and set it to boot automatically (`systemctl start/ enable sshd`). Modify `/etc/ssh/sshd_config` (backup first). Critical configurations: Change the port (e.g., 22→2222 to prevent brute-force attacks), disable root login (`PermitRootLogin no`), allow specific users (`AllowUsers`), and disable password login in favor of key-based authentication (generate a key pair locally and use `ssh-copy-id` to transfer it to the server). Restart `sshd` after changes. Client connection: Use PuTTY on Windows, and the terminal on Linux/macOS with the command `ssh username@IP -p port`; key-based authentication is more secure. Security notes: Allow the port through the firewall (UFW or cloud security groups), disable direct root login, and regularly update the system and SSH. Common issues: Timeout (check IP/network), connection refused (check port/service), permission errors (
Read MoreUnderstanding Linux SSH Service: A Complete Guide to Configuration and Usage
SSH is a secure remote management protocol for Linux servers, replacing insecure services like Telnet by ensuring data security through encrypted transmission. Its advantages include high security (default AES/RSA encryption), cross-platform compatibility, and rich features such as file transfer. It consists of the server-side `sshd` (listening on port 22) and the client-side `ssh`. Installation varies: for Ubuntu/Debian, install and start `sshd` via `apt`; for CentOS/RHEL, use `yum`. Verification involves checking service status and port availability. Basic client login is done with `ssh username@IP`. Passwordless login requires generating a key pair and copying the public key to the server. Server configuration is managed via `sshd_config`, allowing modifications such as changing the port, disabling direct root login, or password-based authentication. After configuration changes, restart the service. Common issues require checking service operation, port accessibility, and firewall settings. SSH is a must-have skill for system administrators, requiring mastery of installation, configuration, and basic usage.
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