Click the Secure Shell (SSH) Access link from the Hosting panel.
Access > Secure Shell Access (SSH)
Take note of your Host Name, User Name and Password. If you do not know the current password, set a new password at this time.
SSH User Data panel
Click anywhere on the Desktop of your Macintosh. At the top you should see the Finder menu. Select Go > Applications.
Find the Utilities folder and double-click it or click the arrow next to the folder to expand it.
Find the Terminal utility and double-click it to open.
Overview of available utilities
When the Terminal window opens, type the command
and press ENTER. You will need to replace u11111111 with your User Name and replace HostName.com your your Host Name from the 1&1 Control Panel.
If this is your first time connecting, you will be informed that the secure fingerprint is unknown. Type yes and click ENTER at the Are you sure you want to continue connecting (yes,no)? prompt.
You will then be informed the fingerprint has been permanently stored and you will then be prompted for a password. Please type out the password (as you type, the characters typed will not display on the screen, this is normal) and press ENTER.
You should then see a disclaimer message and be presented with a command prompt. You have now successfully logged in!
For additional information, you may want to reference: