LinkedIn has recently added two-step verification for users. This is an optional measure you can activate to protect your LinkedIn account and connections. Emil Protalinski at The Next Web does a good job explaining this new feature.
For those who don’t know, two-step verification requires you to use more than one form of verification to access an account. Typically, this information includes “knowing something” such as a password and “having something” such as a mobile device.
To use this on your account click Privacy and Settings. Then choose Manage Security Settings. Select Account and click on the green "Turn On" link under "Two-step verification". Hit done and follow the next steps. This presentation from LinkedIn will help walk you through the steps.
We take so much time to build strong connections on LinkedIn, it is wise to do everything we can to protect them.