Secure Your SSH Logins: How to enable SSH 2FA on AlmaLinux
Introduction
Enabling two-factor authentication (2FA) for SSH logins on AlmaLinux significantly enhances your system’s security by adding an extra layer of protection. In this tutorial, we'll guide you through the process of setting up 2FA, ensuring your SSH connections are more secure against unauthorized access.
This method integrates the use of Google Authenticator, providing a simple and effective way to bolster your server’s defense. Follow these detailed steps to configure 2FA on your AlmaLinux system, and safeguard your data with an additional verification step every time you log in.
Install the Google Authenticator on AlmaLinux
sudo dnf install epel-release -y
sudo dnf install google-authenticator qrencode qrencode-libs -y
After install completes, I will create a new secret key in ~/.ssh directory
Run command as follows
google-authenticator -s ~/.ssh/google_authenticatorThe output terminal as below
[root@DevopsRoles ~]# google-authenticator -s ~/.ssh/google_authenticator
Do you want authentication tokens to be time-based (y/n) y
Warning: pasting the following URL into your browser exposes the OTP secret to Google:
https://www.google.com/chart?chs=200x200&chld=M|0&cht=qr&chl=otpauth://totp/root@DevopsRoles.com%3Fsecret%3DDXFSMCJ42VQ7FPMS2VAJ3CIJIE%26issuer%3DDevopsRoles.com
Your new secret key is: DXFSMCJ42VQ7FPMS2VAJ3CIJIE
Your verification code is 222214
Your emergency scratch codes are:
36072722
12212187
31577834
31344084
92578576
Do you want me to update your "/root/.ssh/google_authenticator" file? (y/n) y
Do 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) y
By default, a new token is generated every 30 seconds by the mobile app.
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. This allows for a
time skew of up to 30 seconds between authentication server and client. 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 will permit for a time skew of up to 4 minutes
between client and server.
Do you want to do so? (y/n) y
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.
By default, this limits attackers to no more than 3 login attempts every 30s.
Do you want to enable rate-limiting? (y/n) y
[root@DevopsRoles ~]#
You use mobile device to Get verification codes with Google Authenticator.
Configure SSH and PAM
Set up SSH
sudo vi /etc/ssh/sshd_config
Make sure both UsePAM and ChallengeResponseAuthentication are set to yes.
The output should look like this:
[root@DevopsRoles ~]# egrep "ChallengeResponseAuthentication|UsePAM yes" /etc/ssh/sshd_config | grep -v "#"Setting PAM
ChallengeResponseAuthentication yes
UsePAM yes
sudo vi /etc/pam.d/sshd
Add the following line at the bottom:
auth required pam_google_authenticator.so secret=${HOME}/.ssh/google_authenticatorRestart ssh
sudo systemctl restart sshdLog into the server. For example, log in to the root account as shown in the picture.
Conclusion
You have successfully enabled SSH 2FA on AlmaLinux, enhancing your system's security with an extra layer of protection. I hope this guide has been helpful to you. Thank you for reading and supporting the DevopsRoles page!
Comments
Post a Comment