{"id":21992,"date":"2017-04-20T07:19:37","date_gmt":"2017-04-20T12:19:37","guid":{"rendered":"https:\/\/www.rosehosting.com\/blog\/?p=21992"},"modified":"2022-06-03T03:42:12","modified_gmt":"2022-06-03T08:42:12","slug":"secure-your-ssh-using-two-factor-authentication-on-ubuntu-16-04","status":"publish","type":"post","link":"https:\/\/www.rosehosting.com\/blog\/secure-your-ssh-using-two-factor-authentication-on-ubuntu-16-04\/","title":{"rendered":"Secure SSH using two-factor authentication on Ubuntu 16.04"},"content":{"rendered":"<div id=\"bsf_rt_marker\"><\/div><p><img decoding=\"async\" class=\"alignnone size-full wp-image-24900\" src=\"https:\/\/www.rosehosting.com\/blog\/wp-content\/uploads\/2017\/04\/Secure-SSH-using-two-factor-authentication-on-Ubuntu-16.04.jpg\" alt=\"Secure SSH using two-factor authentication on Ubuntu 16.04\" width=\"1200\" height=\"600\" srcset=\"https:\/\/www.rosehosting.com\/blog\/wp-content\/uploads\/2017\/04\/Secure-SSH-using-two-factor-authentication-on-Ubuntu-16.04.jpg 1200w, https:\/\/www.rosehosting.com\/blog\/wp-content\/uploads\/2017\/04\/Secure-SSH-using-two-factor-authentication-on-Ubuntu-16.04-150x75.jpg 150w, https:\/\/www.rosehosting.com\/blog\/wp-content\/uploads\/2017\/04\/Secure-SSH-using-two-factor-authentication-on-Ubuntu-16.04-300x150.jpg 300w, https:\/\/www.rosehosting.com\/blog\/wp-content\/uploads\/2017\/04\/Secure-SSH-using-two-factor-authentication-on-Ubuntu-16.04-768x384.jpg 768w, https:\/\/www.rosehosting.com\/blog\/wp-content\/uploads\/2017\/04\/Secure-SSH-using-two-factor-authentication-on-Ubuntu-16.04-1024x512.jpg 1024w, https:\/\/www.rosehosting.com\/blog\/wp-content\/uploads\/2017\/04\/Secure-SSH-using-two-factor-authentication-on-Ubuntu-16.04-860x430.jpg 860w, https:\/\/www.rosehosting.com\/blog\/wp-content\/uploads\/2017\/04\/Secure-SSH-using-two-factor-authentication-on-Ubuntu-16.04-680x340.jpg 680w, https:\/\/www.rosehosting.com\/blog\/wp-content\/uploads\/2017\/04\/Secure-SSH-using-two-factor-authentication-on-Ubuntu-16.04-500x250.jpg 500w, https:\/\/www.rosehosting.com\/blog\/wp-content\/uploads\/2017\/04\/Secure-SSH-using-two-factor-authentication-on-Ubuntu-16.04-400x200.jpg 400w, https:\/\/www.rosehosting.com\/blog\/wp-content\/uploads\/2017\/04\/Secure-SSH-using-two-factor-authentication-on-Ubuntu-16.04-200x100.jpg 200w, https:\/\/www.rosehosting.com\/blog\/wp-content\/uploads\/2017\/04\/Secure-SSH-using-two-factor-authentication-on-Ubuntu-16.04-50x25.jpg 50w\" sizes=\"(max-width: 1200px) 100vw, 1200px\" \/><\/p>\n<p>In this tutorial, we will describe the necessary steps to configure two-factor authentication (2FA) using Google authenticator on an <a href=\"https:\/\/www.rosehosting.com\/ubuntu-hosting.html\">Ubuntu 16.04 VPS<\/a>. This application includes implementations of one-time passcode generators for several mobile platforms. This method adds another layer of protection to your server adding an extra step to the basic login procedure. <!--more--><\/p>\n<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_65 counter-hierarchy ez-toc-counter ez-toc-transparent ez-toc-container-direction\">\n<p class=\"ez-toc-title\">Table of Contents<\/p>\n<label for=\"ez-toc-cssicon-toggle-item-6632efa31de07\" class=\"ez-toc-cssicon-toggle-label\"><span class=\"ez-toc-cssicon\"><span class=\"eztoc-hide\" style=\"display:none;\">Toggle<\/span><span class=\"ez-toc-icon-toggle-span\"><svg style=\"fill: #999;color:#999\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" class=\"list-377408\" width=\"20px\" height=\"20px\" viewBox=\"0 0 24 24\" fill=\"none\"><path d=\"M6 6H4v2h2V6zm14 0H8v2h12V6zM4 11h2v2H4v-2zm16 0H8v2h12v-2zM4 16h2v2H4v-2zm16 0H8v2h12v-2z\" fill=\"currentColor\"><\/path><\/svg><svg style=\"fill: #999;color:#999\" class=\"arrow-unsorted-368013\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"10px\" height=\"10px\" viewBox=\"0 0 24 24\" version=\"1.2\" baseProfile=\"tiny\"><path d=\"M18.2 9.3l-6.2-6.3-6.2 6.3c-.2.2-.3.4-.3.7s.1.5.3.7c.2.2.4.3.7.3h11c.3 0 .5-.1.7-.3.2-.2.3-.5.3-.7s-.1-.5-.3-.7zM5.8 14.7l6.2 6.3 6.2-6.3c.2-.2.3-.5.3-.7s-.1-.5-.3-.7c-.2-.2-.4-.3-.7-.3h-11c-.3 0-.5.1-.7.3-.2.2-.3.5-.3.7s.1.5.3.7z\"\/><\/svg><\/span><\/span><\/label><input type=\"checkbox\"  id=\"ez-toc-cssicon-toggle-item-6632efa31de07\"  aria-label=\"Toggle\" \/><nav><ul class='ez-toc-list ez-toc-list-level-1 ' ><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/www.rosehosting.com\/blog\/secure-your-ssh-using-two-factor-authentication-on-ubuntu-16-04\/#1-Login-via-SSH\" title=\"1. Login via SSH\">1. Login via SSH<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/www.rosehosting.com\/blog\/secure-your-ssh-using-two-factor-authentication-on-ubuntu-16-04\/#2-Update-the-System-Packages\" title=\"2. Update the System Packages\">2. Update the System Packages<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/www.rosehosting.com\/blog\/secure-your-ssh-using-two-factor-authentication-on-ubuntu-16-04\/#3-Install-Google-Authenticator\" title=\"3. Install Google Authenticator\">3. Install Google Authenticator<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/www.rosehosting.com\/blog\/secure-your-ssh-using-two-factor-authentication-on-ubuntu-16-04\/#4-Run-Google-Authenticator\" title=\"4. Run Google Authenticator\">4. Run Google Authenticator<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/www.rosehosting.com\/blog\/secure-your-ssh-using-two-factor-authentication-on-ubuntu-16-04\/#5-Configure-the-Authenticator-to-Generate-One-Time-Passwords\" title=\"5.\u00a0Configure the Authenticator to Generate One-Time Passwords.\">5.\u00a0Configure the Authenticator to Generate One-Time Passwords.<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-6\" href=\"https:\/\/www.rosehosting.com\/blog\/secure-your-ssh-using-two-factor-authentication-on-ubuntu-16-04\/#6-Restart-SSH-Server\" title=\"6. Restart SSH Server\">6. Restart SSH Server<\/a><\/li><\/ul><\/nav><\/div>\n<h2><span class=\"ez-toc-section\" id=\"1-Login-via-SSH\"><\/span>1. Login via SSH<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p><a href=\"https:\/\/www.rosehosting.com\/blog\/connect-to-your-linux-vps-via-ssh\/\">Login to your\u00a0 server via SSH<\/a> as user root<\/p>\n<pre>ssh root@IP_Address<\/pre>\n<h2><span class=\"ez-toc-section\" id=\"2-Update-the-System-Packages\"><\/span>2. Update the System Packages<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p><a href=\"https:\/\/www.rosehosting.com\/blog\/update-the-software-on-linux\/\">Update all installed packages<\/a>:<\/p>\n<pre>apt-get update &amp;&amp; apt-get upgrade<\/pre>\n<h2><span class=\"ez-toc-section\" id=\"3-Install-Google-Authenticator\"><\/span>3. Install Google Authenticator<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Install the <strong>Google Authenticator<\/strong> package.<\/p>\n<pre>apt-get install libpam-google-authenticator<\/pre>\n<p>Once the package is installed, run the google-authenticator program to create a key for the user you will be logging with. The program can generate two types of authentication tokens &#8211; <strong>time-based<\/strong> and <strong>one-time tokens<\/strong>. Time-based passwords will change randomly at a certain amount of time, and one-time passwords are valid for a single authentication.<\/p>\n<h2><span class=\"ez-toc-section\" id=\"4-Run-Google-Authenticator\"><\/span>4. Run Google Authenticator<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>In our case, we will use time-based passwords. Run the program to create the keys<\/p>\n<pre>google-authenticator<\/pre>\n<p>You will be asked if you want the authentication to be time-based.<\/p>\n<pre>Do you want authentication tokens to be time-based (y\/n) y<\/pre>\n<p>Big QR code will be generated in your terminal. You can scan the code with the authenticator application on your Android\/iOS\/Windows phone or tablet or enter the secret key generated on the screen.<\/p>\n<p>Emergency scratch codes will also be generated. You can use these codes for authentication in case you lose your mobile device.<\/p>\n<pre>Your emergency scratch codes are:\n80463533\n68335920\n89221348\n12489672\n11144603<\/pre>\n<p>Save the authentication settings for the root user by answering YES to the next question<\/p>\n<pre>Do you want me to update your \"\/root\/.google_authenticator\" file (y\/n) y<\/pre>\n<h2><span class=\"ez-toc-section\" id=\"5-Configure-the-Authenticator-to-Generate-One-Time-Passwords\"><\/span>5.\u00a0Configure the Authenticator to Generate One-Time Passwords.<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Next, you can configure the authenticator to generate one-time passwords. Since they last 30 seconds, all generated passwords can be used once.<\/p>\n<pre>Do you want to disallow multiple uses of the same authentication\ntoken? This restricts you to one login about every 30s, but it increases\nyour chances to notice or even prevent man-in-the-middle attacks (y\/n) y<\/pre>\n<p>You can use the next setting if you have time syncing issues across your devices, so we will not use this option<\/p>\n<pre>By default, tokens are good for 30 seconds and in order to compensate for\npossible time-skew between the client and the server, we allow an extra\ntoken before and after the current time. If you experience problems with poor\ntime synchronization, you can increase the window from its default\nsize of 1:30min to about 4min. Do you want to do so (y\/n) n<\/pre>\n<p>The next setting prevents brute-force attacks. You will only have three chances per 30 seconds to enter the correct password.<\/p>\n<pre>If the computer that you are logging into isn't hardened against brute-force\nlogin attempts, you can enable rate-limiting for the authentication module.\nBy default, this limits attackers to no more than 3 login attempts every 30s.\nDo you want to enable rate-limiting (y\/n) y<\/pre>\n<p>Now we have the Google Authenticator application configured and the next step is to configure the authentication settings in openSSH. To do so, open the &#8220;\/etc\/pam.d\/sshd&#8221; file and add the following line to the end of the file:<\/p>\n<pre># vim \/etc\/pam.d\/sshd\n\nauth required pam_google_authenticator.so<\/pre>\n<p>Save the changes, and open the &#8220;\/etc\/ssh\/sshd_config&#8221; file and enable Challenge Response Authentication.<\/p>\n<pre># vim \/etc\/ssh\/sshd_config\n\nChallengeResponseAuthentication yes<\/pre>\n<h2><span class=\"ez-toc-section\" id=\"6-Restart-SSH-Server\"><\/span>6. Restart SSH Server<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Save the file, and restart the SSH server for the changes to take effect.<\/p>\n<pre>systemctl restart ssh<\/pre>\n<p>If you closely followed this tutorial, two-factor authentication is enabled on your server and every time you try to login to your Ubuntu VPS via SSH you will have to enter your user&#8217;s password and the verification code generated by Google Authentication application on your mobile device.<\/p>\n<hr \/>\n<p>Of course, you don\u2019t have to secure SSH using two-factor authentication on Ubuntu 16.04, if you use one of our Linux VPS Hosting services, in which case you can simply ask our expert Linux admins to secure SSH using two-factor authentication on Ubuntu 16.04. They are available 24\u00d77 and will take care of your request immediately.<\/p>\n<p><span style=\"color: #ff0000;\"><strong>PS.<\/strong><\/span> If you liked this post on how to\u00a0secure SSH using two-factor authentication on Ubuntu 16.04,\u00a0 please share it with your friends on the social networks using the buttons below or leave a reply in the comments section. Thanks.<\/p>\n<p>A new version is available here: <a href=\"https:\/\/www.rosehosting.com\/blog\/how-to-set-up-multi-factor-authentication-for-ssh-on-ubuntu-20-04\/\">Set Up Multi-Factor Authentication for SSH on Ubuntu 20.04<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>In this tutorial, we will describe the necessary steps to configure two-factor authentication (2FA) using Google authenticator on an Ubuntu &#8230; <\/p>\n<p class=\"read-more-container\"><a title=\"Secure SSH using two-factor authentication on Ubuntu 16.04\" class=\"read-more button\" href=\"https:\/\/www.rosehosting.com\/blog\/secure-your-ssh-using-two-factor-authentication-on-ubuntu-16-04\/#more-21992\" aria-label=\"Read more about Secure SSH using two-factor authentication on Ubuntu 16.04\">Read More<\/a><\/p>\n","protected":false},"author":4,"featured_media":24900,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1703,1698],"tags":[1552,65,68,59],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v22.6 - 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