Comments on Secure SSH with Google Authenticator Two-Factor Authentication on CentOS 7
SSH access is always critical and you might want to find ways to improve the security of your SSH login. In this article we will see how we can secure SSH with simple two factor authentication by using Google Authenticator. Before using it you have to integrate the SSH daemon on your server with Google Authenticator one time password protocol TOTP and another restriction is that you must have your android phone with you all the time or at least the time you want SSH access. This tutorials is written for CentOS 7.
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Comments
google and security in one sentence...something is wrong here.
What provides the google-authenticator package? I get this:
[root@z1223lc7 ~]# yum install google-authenticator
Loaded plugins: fastestmirror, langpacks
base | 3.6 kB 00:00
elrepo | 2.9 kB 00:00
epel/x86_64/metalink | 14 kB 00:00
epel-spotify | 2.9 kB 00:00
extras | 3.4 kB 00:00
google-chrome | 951 B 00:00
nux-dextop | 2.9 kB 00:00
updates | 3.4 kB 00:00
Loading mirror speeds from cached hostfile
* base: repos.dfw.quadranet.com
* elrepo: elrepo.org
* epel: mirrors.tummy.com
* extras: mirrors.centarra.com
* nux-dextop: mirror.li.nux.ro
* updates: mirrors.umflint.edu
No package google-authenticator available.
Error: Nothing to do
Same here Denver.Did you find a solution?
I can't find the package in the standard or EPEL Centos 7 repo. please advise...
need to add the EPEL (Extra Packages for Enterprise Linux) repo.
sudo yum install https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm
cd /opt/ wget https://google-authenticator.googlecode.com/files/libpam-google-authenticator-1.0-source.tar.bz2 tar -xvzf libpam-google-authenticator-1.0-source.tar.bz2 cd libpam-google-authenticator-1.0 make make installNow, run the Google authenticator on your server and answer each of the questions with yes$ google-authenticatorDo you want authentication tokens to be time-based (y/n) y https://www.google.com/chart?chs=200x200&chld=M|0&cht=qr&chl=otpauth://totp/root@YOURHOSTNAME%3Fsecret%3DWYD4YCGEE5N4M3LA Your new secret key is: WYD4YCGEE5N4M3LA Your verification code is 188127 Your emergency scratch codes are: 60086389 28918071 88502143 60873576 90892542 Do you want me to update your "/root/.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, tokens are good for 30 seconds and 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. If you experience problems with poor time synchronization, you can increase the window from its default size of 1:30min to about 4min. 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
Open the URL given after answering the first question and scan the QR code using the Google Authenticator application on your smartphone. That’s all. A new verification code will be generated every 30 seconds.
Now you will need to enable Google authenticator for SSH logins. Open PAM’s configuration file
vi /etc/pam.d/sshdAnd add the following line at the top
auth required pam_google_authenticator.soOpen the SSH configuration file and ensure that the ‘ChallengeResponseAuthentication‘ line is set to yes
ChallengeResponseAuthentication yes
Save the changes and restart the SSH service:
service sshd restart
Now, every time you try to SSH into your server you will be prompted to enter the verification code displayed in your Google Authenticator application.
login as: Verification code: Password:
Hope this will help some one
I know this is against a bunch of different 'golden rules' but... you can just download and use the Fedora 23 rpm. I have been running it since whomever decided to remove it from EPEL for EL7.
Currently the following works on a fully-patched CentOS 7 and RHEL7.2 systems.
One missing dependency I had to pull in:
yum -y install pam-devel
Thanks for the write-up.
This is not working in centos 6.8
Hey, try this command:
chcon -t ssh_home_t /root/.google_authenticator To get the permissions right for CentOS