[Samba] ODP: Re: freeradius + NTLM + samba AD 4.5.x

Kacper Wirski kacper.wirski at gmail.com
Tue Mar 27 20:40:13 UTC 2018


I can definately confirm that it's working.

My basic setup is:

1) Samba 4.7.6 AD DC (2 of them), compiled from source, on centos 7

2) Freeradius 3.0.13 + samba 4.6.2 as domain member, packages straight 
from centos repo. // I  tested also on freeradius 3.0.14 and samba 4.7.x

smb.conf on the DC is pretty basic, most important is obviously in 

         ntlm auth = mschapv2-and-ntlmv2-only

On server with freeradius + samba 4.6.2:

machine is added to AD using samba with net ads join.

Most important configuration to make mschapv2 only with ntlmv1 overall 
disabled (except for mschapv2) is setting in freeradius in 

mschap {


ntlm_auth = "/path/to/ntlm_auth *--allow-mschapv2* --request-nt-key 
--username=%{mschap:User-Name} --domain=WINDOWSDOMAIN 

OR (if your Freeradius supports it)

winbind_username = "%{%{mschap:User-Name}:-00}"
winbind_domain = "WINDOWSDOMAIN"

The former works just fine, the latter requires freeradius to be built 
with winbind auth, for example for centos i had to rebuild rpm and add 
to ./configure path to winbind libraries.

That's all that's needed to change from the "standard", well documented  
freeradius/AD integration for the integration.

If there are going to be password changes with freeradius ("your 
password has expired" - type - scenarios) You should probably also 
configure in /mods-available/mschap additionaly:

passchange {
                 ntlm_auth = "/path/to/ntlm_auth 
--helper-protocol=ntlm-change-password-1 *--allow-mschapv2*"
                 ntlm_auth_username = "username: %{mschap:User-Name}"
                 ntlm_auth_domain = "nt-domain: WINDOWSDOMAIN"

I'm saying "should probably configure" because  with the settings as 
above it works just fine, so even it's unnecessary, it doesn't break 
anything, and unfortunately I was unable to test if it works (I doubt 
it) without this option while denying ntlmv1 overall on ad dc.

If everything works as intented, in the AD DC audit log You will see 
something like this:
{"timestamp": "some-date0", "type": "Authentication", "Authentication": 
{"version": {"major": 1, "minor": 0}, "status": "NT_STATUS_OK", 
"localAddress": "ipv4:xxx.xxx.xxx.xxx", "remoteAddress": 
"ipv4:xxx.xxx.xxx.xxx:58046", "serviceDescription": "SamLogon", 
"authDescription": "network", "clientDomain": "WINDOWSDOMAIN", 
"clientAccount": "some-user", "workstation": "\\\\SOME-HOST", 
"becameAccount": "some-user", "becameDomain": "WINDOWSDOMAIN", 
"becameSid": "SOME-SID", "mappedAccount": "some-user", "mappedDomain": 
"WINDOWSDOMAIN", "netlogonComputer": "SOME-HOST", 
"netlogonTrustAccount": "SOME-HOST$", "netlogonNegotiateFlags": 
"0x610FFFFF", "netlogonSecureChannelType": 2, "netlogonTrustAccountSid": 
"somesid, *"passwordType": "MSCHAPv2"*}}

Without "--allow-mschapv2" You would see "passwordType":"NTLMv1".

Also I have no idea when ntlm_auth --allow-mschapv2 option was added?

W dniu 27.03.2018 o 10:06, Rowland Penny via samba pisze:
> On Tue, 27 Mar 2018 09:36:42 +0200
> "k.wirski via samba" <samba at lists.samba.org> wrote:
>> ok, tested it, and it works.
>> so to summarize:
>> on samba ad 4.7.x  in smb.conf "ntlm auth" is set to
>> "mschapv2-and-ntlmv2-only" fr + samba domain member (4.6 and 4.7) in
>> mods-available/mschap you have to add to ntlm_auth --allow-mschapv2
>> to the whole string OR just use winbind method, which sets correct
>> flag without explicitly adding it.
> Not sure it will work with 4.6 as it doesn't have the required
> 'mschapv2-and-ntlmv2-only' option for 'ntlm auth'
>> with those settings ntlmv1 is blocked except for mschapv2, and it's
>> nicely visible in samba auth_audit log.
>> I also tried password change with ntlm_auth (for expired password at
>> logon via FR) and it works fine too, with added --allow-mschapv2.
>> I completely missed ntlm_auth option --allow-mschapv2!
>> Thank You for pointing it out.
> If you can let us know just what you changed to get it working, I will
> put something on the Samba wiki.
> Rowland

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