Google Authenticator

Docker

I do not understand the relationship between FreeRADIUS, PAM, Google Authenticator, and SSS as much as I should. This took me several days trying to work this out until I found the referenced instructions on GitHub. Thankfully I was able to get a test container working, so now I just need to PROPERLY record the steps I took. Gong back to what I had in 2016 was not sufficient.

Host Prep

This is not a fully contained solution. I ran into problems with SSS and kerberose authentication into AD. The problem stems from two sides

1. The kerberos works out of the secure kernel. Which causes unprivileged containers the inability to access this.
2. Kerberos likes a stable network. Containers tend to jump around and this causes problems.

So I settled on enrolling the host into AD as those are more stable, and because I will be using EC2 instances until I learn the orchastrator in AWS.

• Make sure your DNS solution is configured to resolve the domain you want to authenticate to.

sudo yum -y upgrade
sudo yum -y install yum-cron oddjob oddjob-mkhomedir sssd samba-common-tools realmd docker
sudo realm join -U <username> <domain>

Container build

I normally work with CentOS while the FreeRadius containers are based on Debian/Ubuntu. So for this we want to build our own image using the following template. This could be made smaller if I would compile the pam module outside the container and simply add it in, but I wanted to compile it the container just for the fun of it. This makes a number of packages unnecessary.

One thing I needed to make my "app" to work is the ability to send emails. Sendmail is what I currently use to make this happen, but the one thing I was missing for hours was a properly formatted hosts line. It MUST be very specific (maybe I just don't understand MTAs? Possible)

NOTE This is a work in progress. There is a problem editing the hosts file using sed for some reason. Looking into it

FROM docker.io/centos:latest
RUN yum upgrade -y
RUN yum install -y freeradius freeradius-utils google-authenticator krb5-workstation \
openldap-clients mysql realmd oddjob oddjob-mkhomedir sssd samba-common-tools git \
autoconf dh-autoreconf cmake automake libtool.x86_64 pam-devel sendmail
RUN git clone https://github.com/google/google-authenticator-libpam.git
RUN cd /google-authenticator-libpam; ./bootstrap.sh
RUN cd /google-authenticator-libpam; ./configure && make; make install
RUN sed -i 's/user\ =\ radiusd/user\ =\ root/; s/group\ =\ radiusd/group\ =\ root/' /etc/raddb/radiusd.conf
RUN sed -i "s/^#\\tpam/\\tpam/" /etc/raddb/sites-enabled/default
RUN ln -s /etc/raddb/mods-available/pam /etc/raddb/mods-enabled/pam
RUN echo -e " \n\
client my-client { \n\
        secret          = some-secret-here \n\
        shortname	= name \n\
        ipv4addr        = xxx.xxx.xxx.xxx \n\
} \n\
" >> /etc/raddb/clients.conf
RUN echo "DEFAULT Auth-Type := PAM" >> /etc/raddb/users
RUN rm -f /etc/pam.d/radiusd; echo -e "auth	  required     pam_google_authenticator.so\n\
account    required     pam_nologin.so\n\
account    include	password-auth\n\
session    include	password-auth\n\
" >> /etc/pam.d/radiusd
RUN echo "set smtp=<smtp server>" >> /etc/mail.rc
EXPOSE 1812/TCP
CMD radiusd -f

Build the image

sudo docker build -t googleauth -f Dockerfile .

Start Container

sudo docker run --name radtest -dit -v /var/lib/sss:/var/lib/sss -v /home/ec2-user/ga_codes/home:/home -v /home/ec2-user/ga_scripts:/ga_scripts -v /home/ec2-user/ga_web:/ga_web  googleauth2

CentOS 7

• UPDATE 1 : Ran into an issue following VMWare's outdated instructions. Will have to go back and find out what has changed.
• UPDATE 2 : I believe I have found the problem, and it would be the use of the pam_lsass.so module. It was starring me straight in the face and I missed it.
• UPDATE 3 : This is still a live project and will be completed in the next week or two. Have to deal with other projects first.
• UPDATE 4: When I did decided to go back and make the required changes I found a site that outlines everything I had debugged. It also showed I was right about the PAM modules. At least I know I learned something correctly. Next step is to go back over the steps and create an installation script.

yum install -y git autoconf automake make libtool pam-devel

nano /etc/yum.repos.d/pbis.repo

[PBISO]
name=PBISO
baseurl=http://repo.pbis.beyondtrust.com/yum/pbiso/$basearch
enabled=1
gpgcheck=0

yum -y install pbis-open
git clone https://github.com/google/google-authenticator
cd google-authenticator/libpam
./bootstrap.sh
./configure
./make
./make install
ln -s /usr/local/lib/security/pam_google_authenticator.so /usr/lib64/security/pam_google_authenticator.so
yum install freeradius
ln -s /etc/raddb/mods-enabled/pam /etc/raddb/mods-available/pam
sed -i 's/user = freerad/user = root/' /etc/raddb/radiusd.conf
sed -i 's/group = freerad/group - root/' /etc/raddb/radiusd.conf
nano /etc/raddb/users

DEFAULT Group == “GG_S_GOOGLE_AUTH_DISABLED”, Auth-Type := Reject
Reply-Message = “Your account has been disabled.”
DEFAULT Auth-Type := PAM

sed -i "s/^#\\tpam/\\tpam/" /etc/raddb/sites-enabled/default

Comment out all lines in /etc/pam.d/radiusd then add the following

echo "auth requisite pam_google_authenticator.so forward_pass" >> /etc/pam.d/radiusd
echo "auth required pam_sss.so use_first_pass" >> /etc/pam.d/radiusd

Ubuntu 16.04 LTS

• UPDATE : I have little interest in finishing the Ubuntu install instructions. This is incomplete and some of the steps are wrong. I am leaving it here for reference only

sudo wget http://download.beyondtrust.com/PBISO/8.0.1/linux.deb.x64/pbis-open-8.0.1.2029.linux.x86_64.deb.sh
git clone https://github.com/google/google-authenticator
cd google-authenticator/libpam/
sudo apt install dh-autoreconf
sudo ./bootstrap.sh
./configure
sudo make
sudo make install
sudo apt install freeradius
sudo sed -i 's/^user\ =\ freerad/user\ =\ root/' /etc/freeradius/radiusd.conf
sudo sed -i 's/^group\ =\ freerad/user\ =\ root/' /etc/freeradius/radiusd.conf
sudo nano /etc/freeradius/users

#
# Deny access for a group of users.
#
# Note that there is NO 'Fall-Through' attribute, so the user will not
# be given any additional resources.
#
#DEFAULT        Group == "disabled", Auth-Type := Reject
#               Reply-Message = "Your account has been disabled."
#
DEFAULT Group == “CSP-VMWare.GoogleAuth”, Auth-Type := Reject
Reply-Message = “Your account has been disabled.”
DEFAULT Auth-Type := PAM

#

sudo sed -i 's/^#\ \ \ \ \ \ \ pam/\ \ \ \ \ \ \ \ pam/' /etc/freeradius/sites-enabled/default
sudo nano /etc/pam.d/radiusd

#
# /etc/pam.d/radiusd - PAM configuration for FreeRADIUS
#

# We fall back to the system default in /etc/pam.d/common-*
#

#@include common-auth
#@include common-account
#@include common-password
#@include common-session
auth requisite pam_google_authenticator.so forward_pass
auth required pam_lsass.so use_first_pass

sudo systemctl start freeradius
sudo nano /etc/freeradius/clients.conf

• Modify the following to match your environment

#client some.host.org {
#       secret          = testing123
#       shortname       = localhost
#}

ie

client vcs-vdi-my.domain.com {
       secret          = Imadeasecret!
       shortname       = vcs
}

sudo nano /etc/freeradius/proxy.conf

realm your.domain.com { }

sudo systemctl restart freeradius