[CentOS] Apache/Active Directory authentication

Michael B Allen ioplex at gmail.com
Wed Mar 23 00:58:14 UTC 2011

On Tue, Mar 22, 2011 at 5:55 AM, John Hodrien <J.H.Hodrien at leeds.ac.uk> wrote:
> On Tue, 22 Mar 2011, Michael B Allen wrote:
>> Hi John,
>> You would not have to create "dummy" machine records. The
>> servicePrincipalName attribute on an AD account is multi-valued and
>> clients can request and get a ticket for ANY principal in that list.
>> So you only need one account.
>> And you do not need special permissions if you have an existing keytab
>> because you can use the keytab to authenticate with AD and add
>> servicePrincipalName values to the account itself. At least in theory
>> you can. I don't know if Samba's routine for adding HTTP SPNs is smart
>> enough to know that it needs to not just add servicePrincipalName
>> values but that it will also need to rebuild the keytab.
> Yes, but using the machine principal you're able to request any number of
> service principals that are SERVICENAME/<machinename>.  For this to work in a
> virtual hosting environment, you need multiple machine names (since we're
> talking about making a number of HTTP/<blah> principals).  Whilst I accept

The "<machinename>" of the principal does NOT have to match the actual
machine name. You could create a User object called "alice" with
servicePrincipalName values of HTTP/as1.busicorp.local,
HTTP/mycomputer.net and HTTP/test1 and requesting tickets for any of
those names will work just fine. AD just searches for an account with
a servicePrincipalName value that matches the principal requested for
the service ticket.

Pedantic note: If you have the same servicePrincipalName value on more
than one account, AD will actually choke and not return a ticket at
all (because the request is ambiguous), there is no constraint in AD
to stop people from accidentally adding the same SPN to multiple
accounts and AD will not return any kind of meaningful error about it.


Michael B Allen
Java Active Directory Integration

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