![]() By default, this limits attackers to no more than three login attempts every 30s.ĭo you want to enable rate-limiting? (y/n) y Configure SSH to prompt for the OTP codeĮdit a couple of SSH configuration files to ask for an OTP code as a second-factor authentication. If the computer that you are logging into isn't hardened against brute-force login attempts, you can enable rate-limiting for the authentication module. This will permit for a time skew of up to 4 minutes between client and server. If you experience problems with poor time synchronization, you can increase the window from its default size of 3 permitted codes (one previous code, the current code, the next code) to 17 permitted codes (the 8 previous codes, the current code, and the 8 next codes). This allows for a time skew of up to 30 seconds between authentication server and client. In order to compensate for possible time-skew between the client and the server, we allow an extra token before and after the current time. Do you want me to update your "/home/user/.google_authenticator" file? (y/n) yĭo you want to disallow multiple uses of the same authentication token? This restricts you to one login about every 30s, but it increases your chances to notice or even prevent man-in-the-middle attacks (y/n) yīy default, a new token is generated every 30 seconds by the mobile app. Answer the rest of the questions to complete the process. Using an authenticator app like Google Authenticator on a smartphone, scan the QR code generated from the above command. This generates a QR code on the screen, a secret key, and recovery codes. Do you want authentication tokens to be time-based (y/n) y For most of these questions, answer yes ( y), unless you need something other than the default. Run the following command to begin the configuration process: # google-authenticator Next, configure google-authenticator to generate OTP codes. To do so, open a Terminal window and run the following command: # sudo dnf install google-authenticator -y Implement the Google Authentication moduleįirst, install the Google Authentication module on a Linux machine. In this article, we use the Google PAM module to enable MFA so users can log in by using time-based one-time password (TOTP) codes. Pluggable Authentication Modules (PAM) are the authentication mechanism used in Linux. ![]() The additional information may be a one-time password (OTP) sent to your cell phone via SMS or credentials from an app like Google Authenticator, Twilio Authy, or FreeOTP. Multi-factor authentication requires users to provide more than one piece of information to authenticate successfully to an account or Linux host. When you SSH into a Linux machine, you may be asked for an SSH key pair. Usually, when you sign in to an account or device, you are asked for a username and password. Multi-factor authentication (MFA) is a method of requiring more than one credential to prove your identity. ![]() One way to achieve added security is by adding an extra layer of authentication. With the rising number of breaches and password compromises, we need as many security layers as possible. ![]() Linux system administration skills assessment.A guide to installing applications on Linux.Download RHEL 9 at no charge through the Red Hat Developer program.
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