We’ve open-sourced our duo_unix package for easy, drop-in two-factor authentication to any Unix system. Combined with our hosted service, it’s the simplest way to protect logins to your cloud or datacenter hosts with strong, out-of-band authentication. Here’s how:

1. Set up your Duo account

First, create your new Duo account at duosecurity.com – it’s free for up to 10 users or for any open-source project!

In the Duo admin interface, create a new Unix integration for your host:


You’ll need the resulting integration and secret keys for your duo_unix configuration:


2. Set up login_duo on your Unix system

Next, on your Unix system, download, build and install the duo_unix distribution (or install the appropriate package for your OS: Debian, Ubuntu, etc.):


Once installed, edit /etc/duo/login_duo.conf as root to add your integration and secret keys:


Then as a regular user, test login_duo manually. If everything’s set up correctly, you’ll be prompted to enroll (or check your syslog for errors):


Enroll your phone:


The next time you run login_duo, you’ll be prompted to authenticate with your phone:


3. Enable login_duo on your Unix system

To enable Duo login for individual accounts using SSH pubkeys, use the authorized_keys command option. For example, to verify individual admins authorized to log into a shared root account:


* This also works for user-local installations (e.g. $HOME/bin) without root access in shared web hosting environments — just specify the location of login_duo.conf with -c.

Similarly, you can enable Duo login system-wide to follow any SSH login method (password, pubkey, etc.) for any user. Edit your /etc/sshd_config (or /etc/ssh/sshd_config) to add the following line:

ForceCommand /usr/local/sbin/login_duo

And optionally limit Duo login to a subset of users by UID or group in /etc/duo/login_duo.conf:

group = wheel

The duo_unix PAM configuration is similar if you’d like to protect other PAM-enabled daemons or programs (e.g. sudo).

Let us know if you have any questions or comments!


Free Guide

Two-Factor Authentication Evaluation Guide

This guide walks through some of the key areas of differentiation between two-factor authentication solutions and provides some concrete criteria for evaluating technologies and vendors.


phishing (16)  two-factor-authentication (15)  passwords (13)  healthcare security (11)  malware (7)  ooba (6)  atms (5)  2fa (5)  cloud security (5)  encryption (5)  webinar (5)  financial institutions (5)  financial data breach (5)  transaction-level 2fa (5)  stolen-passwords (5)  healthit (4)  federal cybersecurity (4)  data breaches (4)  hipaa (4)  data breach notification (4)  pci dss (4)  retail (4)  security news (4)  home depot (3)  otp bypass (3)  hipaa security rule (3)  banking security (3)  strong-authentication (3)  two-factor (3)  twitter (3)  e-prescriptions (3)  bank security (3)  healthcare cybersecurity (3)  rig exploit kit (3)  medical devices (3)  defense in depth (3)  retail ebook (3)  stolen credentials (3)  retail data breaches (3)  target (3)  vulnerability (3)  anthem (3)  third-party security (3)  iot security (3)  health it (3) 

Duo is hiring!

View our open positions

Follow Us

Subscribe to our Newsletter

Get product updates, interesting content, and invitations to online and live events.