RSA Authentication – LINUX

Service has been installed and tested on RedHat 6.9 (Santiago), RedHat 7.3 (Maipo) and CentOS 7.4.
This service allows for two-factor authentication using an RSA passcode and user password.

Installation Pre-requisites:

An account, typically a domain user, will need to be available for access, in the first instance these accounts are manually created.  For Example, Joe.Bloggs

Changes must be made to the following files (outlined later), access via root or sudo privileged user:

/etc/ssh/sshd_config

/etc/pam.d/sshd

/etc/sd_pam.conf

The LINUX server IP address MUST be manually added to the RSA Authentication server.
(In the security console click Access > Authentication Agents > Add New)

A copy of the RSA Authentication Manager certificate is required.
(In the security console click Access > Authentication Agents > Download Server Certificate File)

Generated Configuration File (AM_Config.zip) from the RSA Security Console.
(In the security console click Access > Authentication Agents > Generate Configuration File)

UNZIP AM_Config.zip before transfer to server

RSA PAM package (PAM-Agent_v8.0.0.195.11_23_17_04_55_23.tar)
(https://community.rsa.com/community/products/securid/authentication-agent-pam)

Method:

Create /var/ace directory on server host

mkdir /var/ace

Create the Authentication Manager configuration file, sdopts.rec

touch /var/ace/sdopts.rec

Add the server host IP address to the sdopts.rec

sudo vim /var/ace/sdopts.rec

The sdopts.rec file only needs one line

CLIENT_IP=x.x.x.x

where IP is the IP of the host machine

Copy the server.cer and sdconf.rec files to /var/ace folder

sudo cp server.cer sdconf.rec /var/ace

Install two packages to the server to ensure the RSA PAM package will work.

yum install selinux-policy-devel
yum install policycoreutils-python  

**Please note the second package (policycoreutils-python) should be installed as part of the install process of the first one.  This can be verified during the install process of the selinux-policy-devel package.

Install Pam RSA Agent V8.0 (browse to downloaded path, E.G /tmp/)

tar xvf PAM-Agent_v8.0.0.195.11_23_17_04_55_23.tar
cd PAM-Agent_v8.0.0.195.11_23_17_04_55_23
./install_pam.sh

You will now be asked to accept a license agreement.  Scroll to the end of the agreement (space bar).  Type A to accept. Press <RETURN>.  During the install you will be asked a series of question regarding the install path, authentication mode and

  1. Select which operation mode you would like to configure for authentication [0/1/2] :
    Choose option 0 (RSA Authentication Manager with the UDP Protocol)
  2. Enter Directory where sdconf.rec is located [/var/ace] :
    Press <RETURN> (the sdconf.rec file should be located in the /var/ace folder from previous step)
  3. Please enter the root path for the RSA Authentication Agent for PAM directory [/opt] :
    Press <RETURN>

Once successful the install will output the following:


The RSA Authentication Agent for PAM 8.0.0 [195] will be installed in the /opt directory.
pam/
pam/conf/
pam/conf/mfa_api_template.properties
pam/conf/log.properties
pam/lib/
pam/lib/32bit/
pam/lib/32bit/libpamrest32.so
pam/lib/32bit/liblog4cxx.so.10.0.0
pam/lib/32bit/pam_securid.so
pam/lib/64bit/
pam/lib/64bit/liblog4cxx.so.10.0.0
pam/lib/64bit/libpamrest.so
pam/lib/64bit/pam_securid.so
pam/bin/
pam/bin/32bit/
pam/bin/32bit/acetest
pam/bin/32bit/ns_conv_util
pam/bin/32bit/acestatus
pam/bin/64bit/
pam/bin/64bit/acetest
pam/bin/64bit/ns_conv_util
pam/bin/64bit/acestatus

Checking /etc/sd_pam.conf:

VAR_ACE does not exist – entry will be appended

OPERATION_MODE does not exist – entry will be appended

RSATRACELEVEL does not exist – entry will be appended

RSATRACEDEST does not exist – entry will be appended

ENABLE_USERS_SUPPORT does not exist – entry will be appended

INCL_EXCL_USERS does not exist – entry will be appended

LIST_OF_USERS does not exist – entry will be appended

PAM_IGNORE_SUPPORT_FOR_USERS does not exist – entry will be appended

ENABLE_GROUP_SUPPORT does not exist – entry will be appended

INCL_EXCL_GROUPS does not exist – entry will be appended

LIST_OF_GROUPS does not exist – entry will be appended

PAM_IGNORE_SUPPORT does not exist – entry will be appended

AUTH_CHALLENGE_USERNAME_STR does not exist – entry will be appended

AUTH_CHALLENGE_RESERVE_REQUEST_STR does not exist – entry will be appended

AUTH_CHALLENGE_PASSCODE_STR does not exist – entry will be appended

AUTH_CHALLENGE_PASSWORD_STR does not exist – entry will be appended

BACKOFF_TIME_FOR_RSA_EXCLUDED_UNIX_USERS does not exist – entry will be appended

Checking /var/ace/conf/mfa_api.properties:

REST_URL does not exist – entry will be appended

CLIENT_KEY does not exist – entry will be appended

CA_CERT_FILE_PATH does not exist – entry will be appended

CLIENT_ID does not exist – entry will be appended

CONNECT_TIMEOUT does not exist – entry will be appended

READ_TIMEOUT does not exist – entry will be appended

MAX_RETRIES does not exist – entry will be appended

*****************************************************************************

* You have successfully installed RSA Authentication Agent 8.0.0 [195] for PAM

*****************************************************************************

**Please note:  If SELINUX is enabled the output may include SELINUX related information**

Change /etc/pam.d/sshd 

vi /etc/pam.d/sshd

add in the following lines
auth      required              pam_securid.so
auth      required              pam_unix.so

 Using # rem out other auth required lines (for example)

# auth                  required              pam_sepermit.so

Change the sshd_config file 

vi /etc/ssh/sshd_config

Set the following parameters and save the changes:

PasswordAuthentication no

ChallengeResponseAuthentication yes

UsePAM yes

UsePrivilegeSeparation no

**Please note: This file may look different with each version of Linux and also whether SELINUX is enabled **

Change the /etc/sd_pam.conf file

vi /etc/sd_pam.conf

ENABLE_USERS_SUPPORT=1

LIST_OF_USERS=root

PAM_IGNORE_SUPPORT_FOR_USERS=1

PAM_IGNORE_SUPPORT=1

Once you modified the above files restart the SSHD service

REDHAT 6.9 – service sshd restart

REDHAT 7+ - systemctl restart sshd.service

**IMPORTANT NOTICE: DO NOT close the terminal / SSH window!  If there is a misconfiguration you could potentially lock yourself out of the system altogether**

Testing:

During the installation, the PAM installer will add the following scripts to /opt/pam/bin/64bit:

./acestatus

./acetest

./ns_conv_util

To test the RSA Authentication module, type:

./acetest

You should be presented with:

Enter USERNAME:
(enter your domain username, E.G Joe.Bloggs)

Enter PASSCODE:
(using your RSA soft token enter your PIN and generated CODE)

If all of the details are entered correctly, you should receive the following message

Authentication Successful.

Live Tests:
Once you have achieved a successful test status, open up a new SSH session to test the two factor authentication.  During this phase you should will be asked to enter your USERNAME : PASSCODE : PASSWORD
You should now have gained access to the required server.

Troubleshooting:

If your testing was unsuccessful please check the following logs

Cat or tail /var/log/secure to view the RSA logs

tail –f /var/log/secure

Review the entries within the log to ensure the details you enter are correct.

If your “live” login fails, the logs within the RSA Security Console can be reviewed using the Authentication Monitor.

Considerations:

Note the entry within the /etc/sd_pam.conf file

LIST_OF_USERS=root

This section allows you to enter system users that shouldn’t require two factor authentication.  The above example shows the root user.  This is list can contain as many users as necessary (separated with by a colon (:))

For Example:

LIST_OF_USERS=root:nagios:contabuser

Certain system functions may require access to the root user (RSYNC for example), it would be beneficial to exclude this user.