Windows Server 2016 - KDC has no support for encryption type while getting initial credentials

Todd Grayson tgrayson at
Thu Nov 8 11:35:57 EST 2018

You are hard forcing AES for initial ticket granting ticket with the
settings you are using for enctypes.   Unset (comment out) the 3 enctype
lines for one of your tests.  How to comment out lines in the krb5.conf is
covered in the second paragraph here:

Use klist -ef after you successfully authenticate and inspect the ticket
encryption types used.  It will look something like this after commenting
out those lines I mentioned and then retrying your kinit:

dude at host:~$ kinit Administrator at AD.SEC.EXAMPLE.COM
Password for Administrator at AD.SEC.EXAMPLE.COM:
dude at host:~$ klist -ef
Ticket cache: FILE:/tmp/krb5cc_1000
Default principal: Administrator at AD.SEC.EXAMPLE.COM

Valid starting       Expires              Service principal
11/08/2018 09:16:00  11/08/2018 19:16:00  krbtgt/
renew until 11/15/2018 09:15:53, Flags: FRIA
Etype (skey, tkt): arcfour-hmac, aes256-cts-hmac-sha1-96

You can see on the Etype line, by default the inital session key is actualy
rc4-hmac  (arcfour-hmac is same thing, just different names) But the actual
ticket granting ticket. The above example is against a windows 2008 KDC,
but 2016 is probably doing the same thing for backward comparability.

Kerberos will negotiate strongest encryption types by default within the
available configuration.

AD exposes per user account settings in the properties dialog, under
account details, that allow you to set using AES encryption types.  Doing
it for all accounts would be a global policy in AD.  This mail list does
not really cover how to manage active directory as a KDC at that level,
microsoft discussion boards would be best there.

Given you are new to kerberos, I would suggest starting here, reading this
will help you understand your terminology, what to search/google for, how
things work in kerberos, etc.

The administration guide would be next step.

Microsoft AD kerberos info is here, I would start with this AFTER going
through the kerberos tutorial.

On Thu, Nov 8, 2018 at 9:03 AM Silambarasan Madhappan <
silambarasan19 at> wrote:

> Hi,
> I am new to Kerberos.  I am not able to obtain Kerberos
> ticket-granting tickets with strong encryption types from "Windows
> Server 2016 AD"
> My client kerberos configuration as below
> ========================
> $ cat /etc/krb5.conf
> [libdefaults]
> default_realm = CIFS.COM
> default_tkt_enctypes = AES256-CTS-HMAC-SHA1-96 AES128-CTS-HMAC-SHA1-96
> default_tgs_enctypes = AES256-CTS-HMAC-SHA1-96 AES128-CTS-HMAC-SHA1-96
> preferred_enctypes = AES256-CTS-HMAC-SHA1-96 AES128-CTS-HMAC-SHA1-96
> ccache_type = 2
> [realms]
> CIFS.COM = {
> kdc =
> }
> [domain_realm]
> [logging]
> kdc = FILE:/var/log/krb5kdc.log
> admin_server = FILE:/var/log/kadmin.log
> default = FILE:/var/log/krb5lib.log
> [bash4.2]$
> Issue :
> =====
> $ kinit Administrator
> kinit(v5): KDC has no support for encryption type while getting
> initial credentials
> $
> Please let me know  where can I find the kdc configuration types in
> Active Directory (Windows Server 2016) ?
> Do I have to change any configuration on Kerberos Client or Server ?
> Please help me on this.
> Thanks,
> Silambarasan M
> ________________________________________________
> Kerberos mailing list           Kerberos at

Todd Grayson
Customer Operations Engineering
Security SME

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