FreeIPA identity management (IDM) with Active Directory trust

https://www.freeipa.org/page/Demo

LAB Overview

Domains

OS	Realm	Domain	Netbios Name	IP
Windows Server 2019	AD.TEST	ad.test	AD	192.168.68.10
Centos 8	IPA.AD.TEST	ipa.ad.test	IPA	Freeipa Server 192.168.68.11

Servers

ROLE	OS	FQDN	IP
Domain Controller	Server 2019	dc1.ad.test	192.168.68.10
IPA Server	Centos 8	ipa.idm.ad.test	192.168.68.11
IPA Replica	Centos 8	rep.idm.ad.test	192.168.68.12
IPA Client	Centos 8	cli.idm.ad.test	192.168.68.13

Users

User	Domain	Role	Password
administrator	ad.test	Administrator	IDMpass1.
admin	idm.ad.test	Administrator	IDMpass1.
jon	ad.test	Administrator	J0nP4ssw0rd

Prerequirements

This LAB is built with Ansible, Vagrant and Virtualbox. There are Vagrant files inside the provisioning directory. To use the vagrant files, you will need to have done the following:

1. Download and Install VirtualBox
2. Download and Install Vagrant
3. Install Ansible
4. Run the following command to install the necessary Ansible roles for this profile: $ ansible-galaxy collection install -r requirements.yml
5. Install WinRM module for Ansible deployment on Windows and Vagrant package $ pip install pywinrm python-vagrant

Setting up your hosts file

You need to modify your host machine's hosts file (Mac/Linux: /etc/hosts; Windows: %systemroot%\system32\drivers\etc\hosts), adding the line below:

 192.168.68.10  dc1.ad.test
 192.168.68.11  ipa.idm.ad.test
 192.168.68.12  rep.idm.ad.test
 192.168.68.13  cli.idm.ad.test

Setup

Clone this repo

git clone https://github.com/gardart/ansible-freeipa-lab.git
cd ansible-freeipa-lab

Create Active Directory server with Vagrant and Ansible provisioner

cd provisioning/ad
vagrant up

Create FreeIPA server with Vagrant and Ansible provisioner

cd provisioning/ipaserver
vagrant up

Browse to https://ipa.idm.ad.test/ipa/ui and login with user admin and password IDMpass1.

Viewing the status of IdM services

$ ipactl status
Directory Service: RUNNING
krb5kdc Service: RUNNING
kadmin Service: RUNNING
named Service: RUNNING
httpd Service: RUNNING
ipa-custodia Service: RUNNING
pki-tomcatd Service: RUNNING
smb Service: RUNNING
winbind Service: RUNNING
ipa-otpd Service: RUNNING
ipa-dnskeysyncd Service: RUNNING
ipa: INFO: The ipactl command was successful

Create FreeIPA replicas with Vagrant and Ansible provisioner

To create more than one replica, change the numberof_ipa_replicas variable in default.config.yml, the default value is 1.

cd provisioning/ipareplica
vagrant up

Create FreeIPA client with Vagrant and Ansible provisioner

To create more than one client, change the numberof_ipa_clients variable in default.config.yml, the default value is 1.

cd provisioning/ipaclient
vagrant up

Connect FreeIPA with Active Directory (one-way trust)

https://www.freeipa.org/page/Active_Directory_trust_setup#If_IPA_is_subdomain_of_AD

Configure netbios name for idm.ad.test. Support for trusted domain is enabled setting a netbios name for linux domain. This is a prerequisite because active directory expects from remote side a netbios name.

ipa-adtrust-install

Configure DNS forwarder on freeipa server.

ipa dnsforwardzone-add ad.test --forwarder=192.168.68.10 --forward-policy=only

Test records

dig SRV _ldap._tcp.ad.test
dig SRV _kerberos._tcp.ad.test

The SRV query is forwarded to AD and it’s returned the reference of kerberos (port 88) and ldap services (port 389). In this way the sssd client is able to know how to contact the active directory services

On the Windows Active Directory server, we need the same thing:

dnscmd 127.0.0.1 /RecordAdd ad.test ipa.idm.ad.test. A 192.168.68.11
dnscmd 127.0.0.1 /RecordAdd ad.test idm.ad.test. NS ipa.idm.ad.test

Test

nslookup -type=SRV _ldap._tcp.ad.test
nslookup -type=SRV _ldap._tcp.idm.ad.test
nslookup -type=SRV _kerberos._tcp.idm.ad.test

Debugging

IPA health

https://github.com/freeipa/freeipa-healthcheck

ipa-healthcheck --output-type human
ipa-healthcheck --output-type human --failures-only

SSSD Cache

https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/linux_domain_identity_authentication_and_policy_guide/sssd-system-uids https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/6/html/deployment_guide/sssd-cache If the administrator knows that a specific record (user, group, or netgroup) has been updated, then sss_cache can purge the records for that specific account and leave the rest of the cache intact:

sss_cache -u jon@ad.test
id jon@ad.test

Most commonly, this is used to clear the cache and update all records:

sss_cache -E
id jon@ad.test

Manually Deleting Cache Files

systemctl stop sssd; rm -rf /var/lib/sss/{mc,db}/* ; systemctl start sssd

Viewing, starting and stopping the Identity Management services

https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/8/html/configuring_and_managing_identity_management/viewing-starting-and-stopping-the-ipa-server_configuring-and-managing-idm

Debugging AD Trust

https://www.freeipa.org/page/Active_Directory_trust_setup#Debugging_trust

https://www.freeipa.org/page/Active_Directory_trust_setup#Allow_access_for_users_from_AD_domain_to_protected_resources

https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/8/html/configuring_authentication_and_authorization_in_rhel/understanding-sssd-and-its-benefits_configuring-authentication-and-authorization-in-rhel

LE external certificates for httpd

ipa-cacert-manage install isrgrootx1.pem
ipa-cacert-manage install isrg-root-x2.pem
ipa-cacert-manage install lets-encrypt-e1.pem
ipa-cacert-manage install lets-encrypt-e2.pem
ipa-cacert-manage install lets-encrypt-r3.pem
ipa-cacert-manage install lets-encrypt-r4.pem

ipa-certupdate
ipa-server-certinstall -w example_com.key example_com.cer --pin="" --dirman-password=password
ipactl restart
curl --insecure -vvI https://example.com/ipa/ui/ 2>&1 | awk 'BEGIN { cert=0 } /* SSL connection/ { cert=1 } /*/ { if (cert) print }'
'''

### Set Domain resolution order for clients globally
Seperate domains with colon
```shell
ipa config-mod --domain-resolution-order='idm.ad.test:ad.test'

Uninstall IDM Client

Manual uninstallation and cleanup

ipa-client-install --uninstall -U
systemctl stop sssd; rm -rf /var/log/sssd/* /var/lib/sss/{db,mc}/*; systemctl start sssd
rm -f /var/lib/ipa-client/sysrestore/sysrestore.state
dnf reinstall -y krb5-libs sssd

IDM Backup

Check successul backup last 24 hours

awk -v d="$(date -d'24 hours ago' +'%Y-%m-%d %H:%M')" '$1" "$2>=d &&/ipa-backup command was successful/' /var/log/ipabackup.log

IDM first master

https://www.freeipa.org/page/Howto/Promote_CA_to_Renewal_and_CRL_Master#Identifying_current_first_master

FreeIPA marks the first installed master with a CA, as the "first master." It is configured to renew the certificates and make them available to the other clones and to listen to and generate the CRL.

Two important things to note:

There should only one master at a time, otherwise the renewed certificates will step all over each other.
Any CA can be the master. There is nothing magical about it, this is just configuration.

$ ipa config-show

  Maximum username length: 32
  Maximum hostname length: 64
  Home directory base: /home
  Default shell: /bin/sh
  Default users group: ipausers
  Default e-mail domain: idm.ad.test
  Search time limit: 2
  Search size limit: 100
  User search fields: uid,givenname,sn,telephonenumber,ou,title
  Group search fields: cn,description
  Enable migration mode: FALSE
  Certificate Subject base: O=IDM.AD.TEST
  Password Expiration Notification (days): 4
  Password plugin features: AllowNThash, KDC:Disable Last Success
  SELinux user map order: guest_u:s0$xguest_u:s0$user_u:s0$staff_u:s0-s0:c0.c1023$sysadm_u:s0-s0:c0.c1023$unconfined_u:s0-s0:c0.c1023
  Default SELinux user: unconfined_u:s0-s0:c0.c1023
  Default PAC types: MS-PAC, nfs:NONE
  IPA masters: ipa.idm.ad.test, replica1.idm.ad.test, replica2.idm.ad.test, replica3.idm.ad.test, replica4.idm.ad.test
  IPA master capable of PKINIT: ipa.idm.ad.test, replica1.idm.ad.test, replica2.idm.ad.test, replica3.idm.ad.test, replica4.idm.ad.test
  IPA CA servers: ipa.idm.ad.test, replica1.idm.ad.test, replica4.idm.ad.test
  IPA CA renewal master: ipa.idm.ad.test
  Domain resolution order: idm.ad.test:ad.test
  IPA DNS servers: ipa.idm.ad.test, replica1.idm.ad.test, replica4.idm.ad.test

Issues

Disable DNSSEC validation

/etc/named/ipa-options-ext.conf
    dnssec-validation no;

systemctl restart named-pkcs11

Login failure with AD account when KDC is not found. From /var/log/secure sshd[11566]: pam_sss(sshd:auth): received for user jon@ad.test: 6 (Permission denied) Also from /var/log/messages krb5_child[6962][6962]: Cannot find KDC for realm "AD.TEST"

Issue normally related to DNS lookup, check /etc/resolv.conf and if /etc/krb5.conf has dns_lookup_kdc = true https://access.redhat.com/solutions/3242461

Further reading

Determining the appropriate number of replicas

https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/8/html-single/planning_identity_management/index#determining-the-appropriate-number-of-replicas_planning-the-replica-topology