Introduction
In this article, we will discuss how to generate a 6-digit TOTP (Time-based One-Time Password) code using the OATH tool for 20FA (Two-Factor Authentication) SSH login on an Ubuntu box. We will cover the key concepts and provide detailed instructions on how to set up TOTP 2FA for SSH login.
What is TOTP?
TOTP is a type of two-factor authentication that uses a time-based one-time password to provide an additional layer of security. It works by generating a unique, six-digit code that is valid for a short period of time (usually 30 seconds). This code is generated by a TOTP algorithm, which takes the current time and a secret key as inputs.
Setting Up TOTP 2FA for SSH Login
To set up TOTP 2FA for SSH login on an Ubuntu box, we will use the pam_oath.so module, which is a TOTP authentication module for PAM (Pluggable Authentication Modules). This module allows us to use TOTP as a second factor of authentication for SSH login.
Step 1: Installing the Required Packages
First, we need to install the following packages:
libpam-oathoathtool
We can install these packages using the following command:
sudo apt-get install libpam-oath oathtool
Step 2: Generating a TOTP Secret Key
Next, we need to generate a TOTP secret key for our user account. We can do this using the oathtool command as follows:
oathtool --totp -b --base32 8436e373cbdabce46a5d8d019c463a
This is the command that the user is trying to run in the question provided. It generates a TOTP secret key in base32 format, which can be used to authenticate the user.
Step 3: Configuring PAM
Once we have generated the TOTP secret key, we need to configure PAM to use the pam_oath.so module for SSH login. We can do this by editing the /etc/pam.d/sshd file and changing the following line:
@include common-auth
to
auth required pam\_oath.so usersfile=/etc/users.oath
This tells PAM to use the pam\_oath.so module for authentication, and to use the /etc/users.oath file as the user's OATH database.
Step 4: Creating the OATH Database
Next, we need to create the OATH database for our user account. We can do this by creating the /etc/users.oath file and adding the following line:
testuser 8436e373cbdabce46a5d8d019c463a /path/to/totpsecretkey
This tells PAM to use the TOTP secret key located at /path/to/totpsecretkey for the user testuser.
Step 5: Testing the Setup
Finally, we can test the setup by trying to SSH into the Ubuntu box using the testuser account. When prompted for the password, we should enter the TOTP code generated by the oathtool command.
In this article, we have discussed how to generate a 6-digit TOTP code using the OATH tool for 2FA SSH login on an Ubuntu box. We have covered the key concepts and provided a detailed step-by-step guide on how to set up TOTP 2FA for SSH login.
References
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