[Freeipa-users] 2FA and AllowNTHash

[Brian Candler]

On 03/01/2017 15:28, Maciej Drobniuch wrote:
> We have a topo with 3x IPA servers + freeradius.
>
> Freeradius is being used to do mschap with wifi APs. Freeradius 
> connects over ldap to IPA.
>
> In order to do the challange-response thing, freeipa has AllowNTHash 
> enabled.
>
> So I wanted to enable 2FA/OTP but leave the NTHash as is for wifi auth.
>
> In the moment I disallow Password auth for a user and enable OTP the 
> wifi auth stopps working, but the hash clearly stays in ldap.
How are you actually authenticating the user? Are you just reading the 
ipaNTHash out of the LDAP database and letting FreeRADIUS check it? Then 
AFAICS it shouldn't make any different whether OTP is enabled or not.  
Can you show more of your RADIUS config, and the debug output from the 
part which authenticates the user?

I don't use OTP myself, but I wouldn't expect the ipaNTHash to change 
depending on whether OTP is enabled or not (and you're saying the hash 
stays put).

I have what sounds like a similar setup to yours, using FreeRADIUS 
3.0.12 talking to FreeIPA 4.4.0, using a service user which has 
permissions to read out the ipaNTHash directly, based on this blog post:
http://firstyear.id.au/blog/html/2015/07/06/FreeIPA:_Giving_permissions_to_service_accounts..html

ldap config:

         base_dn = 'cn=users,cn=accounts,dc=ipa,dc=example,dc=com'

         sasl {
                 mech = 'GSSAPI'
                 realm = 'IPA.EXAMPLE.COM'
         }

         update {
                 control:NT-Password             := 'ipaNTHash'
                 control:Tmp-String-9            := 'krbPasswordExpiration'
         }

         user {
                 base_dn = "${..base_dn}"
                 filter = "(uid=%{%{Stripped-User-Name}:-%{User-Name}})"
                 scope = "one"
         }

         group {
                 membership_attribute = 'memberOf'
                 name_attributes = 'cn'

                 cacheable_dn = 'yes'
                 cacheable_name = 'no'
         }

default and inner-tunnel authentication is then just:

authenticate {
         Auth-Type PAP {
                 pap
         }

         Auth-Type MS-CHAP {
                 mschap
         }

         eap
}

Also you need to put the service user's keytab somewhere, and set a 
couple of environment variables when it starts, if you want to use 
Kerberos to protect the LDAP connection. Using systemd override:

[Unit]
Requires=dirsrv.target
After=dirsrv.target

[Service]
Environment=KRB5_CLIENT_KTNAME=/etc/radiusd.keytab
Environment=KRB5CCNAME=MEMORY:
Restart=always
RestartSec=5

(Otherwise you can bind with a specific dn and password, but then you 
also need to sort out TLS to secure the LDAP traffic)

There is more magic you can do with the krbPasswordExpiration attribute 
to force the user to do a password change over MSCHAP - but that's now 
straying a long way from what's relevant on a FreeIPA mailing list.

HTH,

Brian.