FreeIPA

Installation

Here are my notes as I fumble my way setting up FreeIPA.

Docker

There is an official Docker container that has a complete FreeIPA installation. This container uses systemd to start up FreeIPA along with the other related services such as OpenLDAP, Bind, and Kerberos. See more at: https://github.com/freeipa/freeipa-container

Use the following docker-compose.yml stack to quickly get started with FreeIPA:

version: '3.3'

services:

  freeipa:
    image: freeipa/freeipa-server:rocky-8
    restart: unless-stopped
    tty: true
    stdin_open: true
    hostname: ipa
    domainname: home.steamr.com
    extra_hosts:
      - "ipa.home.steamr.com:10.1.2.12"
    environment:
      - IPA_SERVER_HOSTNAME=ipa.home.steamr.com
      - IPA_SERVER_IP=10.1.2.12
      - DNS=10.1.0.8
      - TZ=America/Edmonton
    command:
      - ipa-server-install
      - --realm=home.steamr.com
      - --domain=home.steamr.com
      - --ds-password=xxxxxxxxxx
      - --admin-password=xxxxxxxxxx
      - --no-host-dns
      - --setup-dns
      - --auto-forwarders
      - --allow-zone-overlap
      - --no-dnssec-validation
      - --unattended
    sysctls:
      - net.ipv6.conf.all.disable_ipv6=0
    volumes:
      - ./data:/data
      - ./logs:/var/logs
      - /sys/fs/cgroup:/sys/fs/cgroup:ro
    tmpfs:
      - /run
      - /var/cache
      - /tmp
    cap_add:
      - SYS_TIME
    ports:
      - "10.1.2.12:80:80/tcp"
      - "10.1.2.12:443:443/tcp"
      # DNS
      - "10.1.2.12:53:53/tcp"
      - "10.1.2.12:53:53/udp"
      # LDAP(S)
      - "10.1.2.12:389:389/tcp"
      - "10.1.2.12:636:636/tcp"
      # Kerberos
      - "10.1.2.12:88:88/tcp"
      - "10.1.2.12:464:464/tcp"
      - "10.1.2.12:88:88/udp"
      - "10.1.2.12:464:464/udp"

Samba integration

There are 3 methods to using FreeIPA with Samba.

Configure Samba to use FreeIPA as a simple LDAP server, using ldapsam as the passdb backend. This requires a schema change to include the sambaSAMAccount and sambaGroupMapping, and sambaSID object classes. There is a DNA plugin that can be used to update these fields.
Configure Samba to use FreeIPA using ipasam as the passdb backend. This requires ipasam.so on the samba servers.
Configure Samba to use Kerberos. Does not seem to allow users to use password authentication.

Method 1: ldapsam

To use ldapsam, we need to make some changes to the FreeIPA LDAP server by adding sambaSAMAccount and sambaGroupMapping as a default user object class and group object class.

You can either set this in the FreeIPA web interface under configuration, or run:

# ldapmodify <<EOF
dn: cn=ipaConfig,cn=etc,dc=home,dc=steamr,dc=com
changetype: modify
add: ipaUserObjectClasses
ipaUserObjectClasses: sambaSAMAccount
-
add: ipaGroupObjectClasses
ipaGroupObjectClasses: sambaGroupMapping
EOF

We will then need to make a custom DNA (distributed numeric assignment) plugin to update these attributes whenever something related to the object (such as the password) is changed. This can be done by adding a DNA object into LDAP.

ldapadd <<EOF
dn: cn=SambaSid,cn=Distributed Numeric Assignment Plugin,cn=plugins,cn=config
objectClass: top
objectClass: extensibleObject
dnatype: sambaSID
dnaprefix: S-1-5-21-2049073866-1371207509-1214748462
dnainterval: 1
dnamagicregen: assign
dnafilter: (|(objectclass=sambasamaccount)(objectclass=sambagroupmapping))
dnascope: dc=home,dc=steamr,dc=com
cn: SambaSid
dnanextvalue: 2

dn: cn=sambaGroupType,cn=Distributed Numeric Assignment Plugin,cn=plugins,cn=config
objectClass: top
objectClass: extensibleObject
cn: sambaGroupType
dnatype: sambaGroupType
dnainterval: 1
dnamagicregen: assign
dnafilter: (objectClass=sambagroupmapping)
dnascope: dc=home,dc=steamr,dc=com
dnanextvalue: 2
EOF

A ldapsam user entry should have these fields. I don't see these though.

dn: uid=guest2, ou=People,dc=quenya,dc=org
sambaLMPassword: 878D8014606CDA29677A44EFA1353FC7
sambaPwdMustChange: 2147483647
sambaPrimaryGroupSID: S-1-5-21-2447931902-1787058256-3961074038-513
sambaNTPassword: 552902031BEDE9EFAAD3B435B51404EE
sambaPwdLastSet: 1010179124
sambaLogonTime: 0
objectClass: sambaSamAccount
uid: guest2
sambaKickoffTime: 2147483647
sambaAcctFlags: [UX         ]
sambaLogoffTime: 2147483647
sambaSID: S-1-5-21-2447931902-1787058256-3961074038-5006
sambaPwdCanChange: 0

Method 2: ipasam

Install the adtrust components on the FreeIPA server. Install ipa-server-trust-ad and run ipa-adtrust-install --add-sids. This will add the additional IPASAM attributes such as ipaNtPassword in user objects.

# ipa-adtrust-install --add-sids

Ensure that your hostname is set to the FQDN of the hostname otherwise this process will fail. If you are using an external DNS server, ensure that the additional service records are present.

Next, create a new user and then change the user's password. This should populate the ipaNTPassword attribute.

# ipa user-add leo --first=Leo --last=Leung
# ipa group-add-member smbgrp --users=leo

When modifying smb.conf, the service account or bind DN must have access to these new ipasam attributes. You need to create a new set of privilege and role and grant the account access. Create the role and permissions in the web interface or run:

# ipa permission-add "CIFS server can read user passwords"  --attrs={ipaNTHash,ipaNTSecurityIdentifier} --type=user --right={read,search,compare} --bindtype=permission
# ipa privilege-add "CIFS server privilege"
# ipa privilege-add-permission "CIFS server privilege" --permission="CIFS server can read user passwords"
# ipa role-add "CIFS server"
# ipa role-add-privilege "CIFS server" --privilege="CIFS server privilege"

Then, add your service account or bind DN to the 'CIFS server' role.

Method 3: Kerberos

Once this is done, try changing an account password. You should see the ipaNTHash field get populated. This is important as the samba ipasam module will use this.

The following is probably not needed:

Get the SID of your samba server with net getlocalsid. Run the following on your FreeIPA server (using kerberos tickets generated by first running kinit admin).

The freeipa-client-samba tool will configure samba to use your FreeIPA service using kerberos. Users accessing shares would need to do so from a computer that is also on this FreeIPA domain and capable of using kerberos authentication.

To use password authentication, you will need to configure Samba to use FreeIPA's LDAP server as a passdb backend, similar to how you would do it with plain old LDAP. The nice thing with using FreeIPA is that you can configure it to update the LM and NT password hashes whenever the password is changed.

On the Samba server

You can either use a specific binding credential that's shared across all your samba servers, or use the machine's cifs service account to authenticate to the LDAP server.

I tried to do the following using the admin account as the bind DN: (this is probably a bad idea)

[global]
	# freeipa configurations
	passdb backend = ipasam:ldap://home.steamr.com
	ldap admin dn = uid=admin,cn=users,cn=accounts,dc=home,dc=steamr,dc=com
	ldapsam:trusted = yes
	ldap suffix = cn=accounts,dc=home,dc=steamr,dc=com
	ldap user suffix = cn=users,cn=accounts
	ldap machine suffix = cn=computers,cn=accounts
	ldap group suffix = cn=groups,cn=accounts
	ldap passwd sync = only
	ldap ssl = no

Run smbpasswd -w password to set your bind credential passwords.

The other way would be to use a service account. The easiest way is to install the freeipa-client-samba package and then run ipa-client-samba. This should automatically set up the cifs service accounts for this particular samba server, get the samba keytab file in /etc/samba/samba.keytab, and then tweak the smb.conf file to use this keytab file. This also doesn't seem to work as samba doesn't start... hmm

Alternatively, you could try setting a keytab file here so that samba uses a service account in the keytab to authenticate. Perhaps something like this, as outlined in this document.

dedicated keytab file = FILE:/etc/samba/samba.keytab
 kerberos method = dedicated keytab

Your samba server should have the ipa-adtrust-install package. If you don't see it, you likely need to enable a dnf module stream.

Debug samba issues

Use smbclient to help debug issues. smbclient -d 10 -U leo //dnas/home

Tasks

Join a computer to a FreeIPA

Use the ipa-client-install command to add a computer to a FreeIPA server. This should also automatically add a computer account, generate a keytab file, and tweak sssd to use FreeIPA as an authentication mechanism.

# ipa-client-install -U -p admin -w $Password --server ipa.home.steamr.com --domain home.steamr.com --force-join --no-ntp --fixed-primary

Troubleshooting

Error: did not receive Kerberos credentials

Tools such as 'ipa' uses your session's Kerberos tickets for authentication. If you don't have any tickets or if your tickets expired, you may get an ipa: ERROR: did not receive Kerberos credentials error. Fix this by running:

## Renew/obtain Kerberos tickets for 'admin'
# kinit admin
Password for admin@HOME.STEAMR.COM:  ****

Verify if your tickets are available with klist:

# klist
Ticket cache: FILE:/tmp/krb5cc_0
Default principal: admin@STEAMR.COM

Valid starting     Expires            Service principal
03/06/22 14:44:35  03/07/22 14:39:47  krbtgt/STEAMR.COM@STEAMR.COM

Container issues

Don't mount /var/log because the container image symlinks everything into /data. If you do mount /var/log, make sure you make the expected directories or else the installer will fail.
Error with AssertionError: Another instance named 'HOME-STEAMR-COM' may already exist. I can't figure out what's causing lib389 to think there's another instance. I built a container image on top of this image with the assertion patched out. This seemed to have fixed the issue.

FROM freeipa/freeipa-server:rocky-8
RUN sed 's/assert_c(len(insts)/# assert_c(len(insts)/' -i /usr/lib/python3.6/site-packages/lib389/instance/setup.py

Can't find the ipa-adtrust-install package

The FreeIPA packages are under a different app stream repo. Enable it by running dnf -y module enable idm:DL1.