To connect to an SSH server from Windows, macOS, or Linux, you can use the built-in command-line SSH client or third-party SSH clients with a graphical user interface. Below are the general steps to connect to an SSH server using the command-line SSH client (OpenSSH) on each platform:

Windows (using built-in OpenSSH client):

1. Open Command Prompt: Press Win + R, type cmd, and press Enter to open the Command Prompt.
2. Connect to SSH Server: In the Command Prompt, use the following command to connect to the SSH server:
   ssh username@ssh_server_address


   Replace username with your SSH username and ssh_server_address with the IP address or domain name of the SSH server. If your SSH server uses a different port (not the default 22), you can specify it using the -p option: ssh -p port_number username@ssh_server_address.

3. Enter Password or Use SSH Key: After running the command, you will be prompted to enter your SSH password. Alternatively, if you set up SSH key authentication, the client will use the SSH key for authentication instead.

macOS and Linux (using built-in OpenSSH client):

1. Open Terminal: Launch the Terminal application from the Applications folder or use the Spotlight search to find it.
2. Connect to SSH Server: In the Terminal, use the following command to connect to the SSH server:
   ssh username@ssh_server_address


   Replace username with your SSH username and ssh_server_address with the IP address or domain name of the SSH server. If your SSH server uses a different port (not the default 22), you can specify it using the -p option: ssh -p port_number username@ssh_server_address.

3. Enter Password or Use SSH Key: After running the command, you will be prompted to enter your SSH password. Alternatively, if you set up SSH key authentication, the client will use the SSH key for authentication instead.

Graphical SSH Clients (Windows, macOS, Linux):

If you prefer a graphical user interface, there are various third-party SSH clients available, such as PuTTY (Windows), WinSCP (Windows), Cyberduck (macOS), FileZilla (Windows, macOS, Linux), and more. These clients provide a user-friendly interface to connect to SSH servers and manage files securely.

Using the steps above, you can connect to an SSH server and access the remote system’s command-line interface or perform file transfers, depending on your needs and server configuration. Make sure to have proper SSH credentials (username and password or SSH key) and verify that the SSH server is configured to allow remote connections.