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Windows authentication against FreeIPA

Windows authentication against FreeIPA

This article describes direct integration between FreeIPA and Windows machine, i.e. without involving Active Directory server. This article does not apply to configurations where trust between AD and FreeIPA was established. Note also that the described configuration is not supported by FreeIPA development team and also is not supported by Red Hat Enterprise Linux Identity Management product. A work on making possible to login to Windows machines already enrolled into a trusted Active Directory forest is ongoing and is not available yet in any released FreeIPA version.

  1. If you already have AD we recommend using this system with AD and using trusts between AD and IPA.
  2. If you do not have AD then use Samba 4 instead of it. As of Samba 4.3, Samba AD can establish cross-realm trusts. The feature is still incomplete and lacks proper access controls but it can be configured to trust FreeIPA.
  3. If neither of the two options work for you you can configure Windows system to work directly with IPA as described below. It is an option of last resort because IPA does not provide the services windows client expects and FreeIPA development team does not support this mode. If this is good enough for you, fine by us.
  4. Build a native Windows client (cred provider) for IPA using latest Kerberos. This would be really useful if someone does that because we don't have capacity to not build this ourselves. With the native OTP support in IPA it becomes a real business opportunity to provide a native 2FA inside enterprise across multiple platforms. But please do it open source way otherwise we would not recommend you ;-)

FreeIPA is not an Active Directory server

FreeIPA is not a re-implementation of Microsoft Active Directory. FreeIPA is focused on Linux (and other standards compliant) systems.

For this reason FreeIPA without configured AD trust can provide only authentication service for Windows hosts (via standard Kerberos protocol). FreeIPA can't provide account database for Windows hosts in the same way as AD does. You have to create local Windows account and appropriate account mapping for each user if you select direct Windows<=>FreeIPA integration. (This limitation doesn't apply if you use AD trust.)

Project pGina could help you to overcome some limitations.

Configure FreeIPA

1. Create the host principal in the web interface
2. Create IPA users to correspond to Windows users
3. Reset the user's IPA password to a known password using the web interface or CLI,
   the user will be prompted to change at first log in.
4. On the IPA server run
 ipa-getkeytab -s [kdc DNS name]
               -p host/[machine-name]
               -e  arcfour-hmac
               -k krb5.keytab.[machine-name]
 At the prompt enter a random MACHINE_PASSWORD
 (you will enter this later on the windows machine too).
 Note: you can change the -e argument to include also
 AES enctypes from FreeIPA 2.1.4 and higher. (FreeIPA ticket 2038)
 Note: Windows machines names cannot exceed 15 characters
  -- pointed out by Han Boetes on 2013-01-03 on freeipa-users mailing list

Configure Windows (ksetup)

1. ksetup /setdomain [REALM NAME]
2. ksetup /addkdc [REALM NAME] [kdc DNS name]
3. ksetup /addkpasswd [REALM NAME] [kdc DNS name]
4. ksetup /setcomputerpassword [MACHINE_PASSWORD] (the one used above)
5. ksetup /mapuser * *
6. Run gpedit.msc, open the key called:
 "Network Security: Configure encryption types allowed for Kerberos”
   Computer Configuration
     Windows Settings
       Security Settings
         Local Policies
           Security Options
 and deselect everything except RC4_HMAC_MD5
7. *** REBOOT ***
8. Add local user accounts for all users that need to be able to log in.
9. Log in as [user]@[REALM] with the initial password, you will be prompted
to change the password then logged in.

Note: Configuring encryption types is not needed from FreeIPA 2.1.4 and higher. (FreeIPA ticket 2038)

The FreeIPA team thanks 'Jimmy' for providing this information on the freeipa-users mailing list. See mailing list archives for the original text. Several amendments were made.