Double Your Security » Linux Magazine : vimarsana.com

Protect your system from unwanted visitors with two-factor authentication.
If the only protection between an attacker and a user account is a password, security-conscious administrators start to get nervous – and rightly so. Although strong passwords can be enforced, carelessness cannot be ruled out. Two-factor authentication (2FA) provides additional protection against unwanted visitors, even if a user chooses a weak password. While the user s password remains as the first authentication factor, a six-digit numerical code with a limited validity period generated by a smartphone authenticator app adds a second factor.
In this article, I will show how to require a one-time code at login (in addition to the user s password) by creating an app on the user s smartphone. This procedure was developed by the Initiative For Open Authentication (OATH) and has been an Internet Engineering Task Force (IETF) standard since 2011.