Configuring the PAM using SSSD

Configure the PAM on Linux using the SSSD service.

The SSSD service must be installed. If it's not installed, install using sudo yum install sssd.
The service must be configured to start when the system reboots. You can perform this configuration using sudo chkconfig sssd on.
Execute the steps Enforcing SELinux when the property SELINUX is set as enforced in file /etc/selinux/config.
You can also set SELINUX=permissive or SELINUX=disabled, which case enforcing SELinux is not required

Note

Restart Linux if you update /etc/selinux/config.

Verify that the /etc/sssd/sssd.conf file exists, has 600 permission, and is owned by the root user. If the file doesn't exist create it as follows and run chmod 600 /etc/sssd/sssd.conf.

/etc/sssd/sssd.conf

[sssd]
config_file_version = 2
services = nss, pam
### domains specify the look up order, 
### which should always be LOCAL and then IDCS.
domains = LOCAL,IDCS
 
[nss]
#Backfill cache at 75%, do not cache bad lookups,
# no in-mem cache
entry_cache_nowait_percentage = 75
### 1 Hour caching for non existent user
entry_negative_timeout = 3600
 
[pam]
pam_id_timeout = 600
 
[domain/LOCAL]
# Prior to 1.15, must use older files provider
id_provider = proxy
proxy_lib_name = files
# Disable authentication, files provider 
# always provides local access, enumerate files
auth_provider = none
access_provider = permit
enumerate = true
 
[domain/IDCS]
re_expression = (?P<domain>[^\\]*?)\\?(?P<name>[^\\]+$)
auth_provider =  proxy
id_provider = proxy
proxy_lib_name = oracle_cloud
proxy_pam_target = sssd_proxy_oracle_cloud
enumerate =  false
cache_credentials = true
# Default cache timeout 90 mins for user/group info entries, 
#before it reaches to IDCS for new updates
entry_cache_timeout = 5400

Optionally, you can configure email addresses as the SSO usernames. To do this, add the line in bold to the /etc/sssd/sssd.conf file to specify the regular expression.

...
[pam]
[domain/proxy_proxy]
re_expression = (?P<domain>[^\\]*?)\\?(?P<name>[^\\]+$)
auth_provider =  proxy
id_provider = proxy
...

Verify the /etc/pam.d/sssd_proxy_oracle_cloud file exists and is owned by the root user. If the file doesn't exist, then create it as the root user and add the following:
/etc/pam.d/sssd_proxy_oracle_cloud file
```
auth          required      pam_oracle_cloud.so
account       required      pam_oracle_cloud.so
password      required      pam_oracle_cloud.so
session       required      pam_oracle_cloud.so
```
Edit the /etc/pam.d/sshd and add the pam_oracle_cloud module:
/etc/pam.d/sshd
```
auth sufficient pam_oracle_cloud.so
```
Note

Add this either before the line auth include password-auth, or auth substack password-auth*.
Edit the /etc/ssh/sshd_config to configure sshd to allow the use of multifactor authentication (MFA):

/etc/ssh/sshd_config

Search for the ChallengeResponseAuthentication property and set it to yes. If the property isn't in the configuration file, add it.

Edit the /etc/opc.conf to let the plugin to interact with IAM:

/etc/opc.conf

#This is sample format of opc.conf file, please use the correct information to configure this file.
#Enter the Oracle Identity Cloud Service tenancy base url.
base_url = https://identity-cloud-service-instance-url
#There is no need to change value of scope.
scope = urn:opc:idm:__myscopes__
#Enter the location of the wallet.
wallet_location = /etc/opc-wallet
#Enter the log level, this is optional and the default is 0, which means no log. 0 - None, 1 - Error, 2 - Info, 3 - Debug.
log_level = 0
#Enter the log file path, this is optional and defaults to /var/log/opc/pam_nss.log
log_file_path = /var/log/opc/pam_nss.log
#Enter the value for proxy usage to connect to Oracle Identity Cloud Service.
#Set the value to 1 to use a proxy and 0 to not use a proxy.
use_proxy=0
#Enter the information below if you set: use_proxy=1
#Enter the proxy url
#proxy_url=http://proxy.example.com
#Enter the proxy port
#proxy_port=80#Enter the username to connect to the proxy url.
#proxy_username=username_example
#Enter the password of username to connect proxy url.
#proxy_pwd=pwd_example

Restart sssd and sshd:
1. For OEL6 & OEL7: authconfig --enablemkhomedir --enablepamaccess --update.
2. For OEL8: authselect select sssd with-mkhomedir with-pamaccess.
3. Run: service sshd restart.
4. Run: service sssd restart.

Oracle Cloud Infrastructure Documentation

Configuring the PAM using SSSD