On Thu, 2017-11-30 at 14:50 -0800, Gordon Messmer via FreeIPA-users wrote:
I'm troubleshooting a problem: A local system account (daemon) needs to access a file on an NFS4 filesystem with sec=krb5. My understanding is that only processes which have a Kerberos ticket are able to access files on such a filesystem, and that seems to be the case on the system I'm troubleshooting.
Suppose I need a keytab to identify the "daemon" user. I don't think I want to create a new user in FreeIPA, since it would have a uid/gid that conflict with the locally defined account. However, I think I do need a keytab for "daemon@DOMAIN". The ipa command doesn't seem to provide a means of creating such a principal.
Should I work directly in kadmin to create the principal and export the keytab? Am I even on the right track?
The reason why NFS wants to authenticate you, is to know what uig/gid it should assign to your user (on the server) to access files. So creating a user is not necessarily a bad idea...
However in some NFS servers you may be able to create mappings from principals to local users. In that case you can use a SPN (Service Principal Name) and associated keytab to gain access.
In freeipa only users can have a 1 component principal such as "daemon@ DOMAIN" normally. If you really just want to use a service I would first explore the possibility of mapping "daemon/hosts.f.q.d.n@REALM" to a user on the NFS server and then just create a normal service and get a keytab for in in IPA.
Simo.