Dell PowerEdge FN I/O Module Configuration Guide 9.10(0.0)

In addition to the capability to access a device using a console connection or a Telnet session, you can also use SSH for secure, protected communication with the device. You can open an SSH session and run commands or script files. This method of connectivity is supported and provides a reliable, safe communication mechanism.

Entering CLI commands Using an SSH Connection

You can run CLI commands by entering any one of the following syntax to connect to a switch using the preconfigured user credentials using SSH:

ssh username@hostname <CLI Command>

or

echo <CLI Command> | ssh admin@hostname

The SSH server transmits the terminal commands to the CLI shell and the results are displayed on the screen non-interactively.

Executing Local CLI Scripts Using an SSH Connection

You can execute CLI commands by entering a CLI script in one of the following ways:

ssh username@hostname <CLIscript.file>

or

cat < CLIscript.file > | ssh admin@hostname

The script is run and the actions contained in the script are performed.

Following are the points to remember, when you are trying to establish an SSH session to the device to run commands or script files:

• There is an upper limit of 10 concurrent sessions in SSH. Therefore, you might expect a failure in executing SSH-related scripts.

• To avoid denial of service (DoS) attacks, a rate-limit of 10 concurrent sessions per minute in SSH is devised. Therefore, you might experience a failure in executing SSH-related scripts when multiple short SSH commands are executed.

• If you issue an interactive command in the SSH session, the behavior may not really be interactive.

• In some cases, when you use an SSH session, when certain show commands such as show tech-support produce large volumes of output, sometimes few characters from the output display are truncated and not displayed. This may cause one of the commands to fail for syntax error. In such cases, if you add few newline characters before the failed command, the output displays completely.

Execution of commands on CLI over SSH does not notice the errors that have occurred while executing the command. As a result, you cannot identify, whether a command has failed to be processed. The console output though is redirected back over SSH.