Facebook has introduced some time ago two-factor authentication for Login. This means that if someone or something tries to login using your account, there will be two steps needed: authentication using username and password (something that you know) and a mobile phone (something that you have).
Set up the two-step authentication
1. Click on the Settings -> Account Settings and then on Security (left menu)
Or go directly here.
2. Activate “Login Approvals” and click on the checkbox.
3. Facebook will explain briefly what happens if you activate this feature. Click on Setup Now.
4. Enter your password
5. Enter your mobile phone number and click on Continue
6. Enter the code you received via SMS
7. Name the device (e.g. <Browser> on <device>) and then click Next.
8. Click on Next …. There has to be a way to approve applications to access your Facebook account when you don’t have access to your mobile. Unfortunately, Facebook allows this only with an App on Android and iPhone. There is nothing that you can print and have with you as Dropbox and Google do.
You can click Close if you don’t have an iPhone or Android device.
Install the special App and generate codes for your devices and applications.
1. Now you have to set up the code generator by clicking on Continue.
2. You need to download and install the App on your device.
3. After you have installed the Facebook App you have to activate the Code Generator in the Facebook App (available on the bottom of the left menu).
4. Tap on the Code Generator and you will see this:
5. Click on Activate.
Immediately after, the App will generate a new code every 30 seconds. See below how you have to enter that code.
6. In order to finalize the setup, you must click on “Finish Setup”. Not doing this, means that you will have to start the process from the beginning next time.
7. After you installed the Code generator in the Facebook App, you can generate such codes.
For example, if you want to login with your iPhone on Facebook, you will need to authenticate it.
This applies also with browsers or other applications that make use of your Facebook account.