Hi George,
These seems to be a krb5 config issue as described in the MIT
documentation:
https://web.mit.edu/kerberos/krb5-1.12/doc/admin/conf_files/krb5_conf.html
That is, it cannot may the host name to the Kerbeross realm. They provide
some guidance in that document. Search for "no translation".
Andy
On Thu, 13 May 2021, George Patargias - STFC UKRI wrote:
> Hello,
>
> I have problems setting krb5 auth with an xrootd service. The following user principal
>
> KVNO Timestamp Principal
> ---- ----------------- --------------------------------------------------------
> 3 01/01/70 01:00:00 [log in to unmask]
>
> obtains the ticket-granting ticket (krgbt) by doing: kinit -kt ./cta-adm-HOST.keytab [log in to unmask]
>
> and then issues admin commands on a host called cta-adm.scd.rl.ac.uk and these commands need to be authorised by an
> XRootD service (the XRootD instance name is cta and the systemd name is cta-frontend.service) running on another host
> called cta-front01.scd.rl.ac.uk. The krb5 auth for this service is configured as
>
> sec.protocol krb5 /etc/cta/cta-frontend.krb5.keytab [log in to unmask]
> sec.protbind * only sss krb5
>
> where the contents of /etc/cta/cta-frontend.krb5.keytab are
>
> KVNO Timestamp Principal
> ---- ----------------- --------------------------------------------------------
> 3 01/01/70 01:00:00 [log in to unmask]
>
> However, any attempt to issue admin commands result in the following error on the xrootd log of this cta service
>
> 210513 13:58:45 32387 XrootdXeq: User authentication failed; Seckrb5: Unable to extract client name;; No translation available for requested principal ([log in to unmask])
>
> This is thrown by this part of the code in XrdSeckrb5/XrdSecProtocolkrb5.cc
>
> // Decode the credentials and extract client's name
> //
> if (!rc)
> {if ((rc = krb5_rd_req(krb_context, &AuthContext, &inbuf,
> (krb5_const_principal)krb_principal,
> krb_keytab, NULL, &Ticket)))
> iferror = (char *)"Unable to authenticate credentials;";
> else if ((rc = krb5_aname_to_localname(krb_context,
> Ticket->enc_part2->client,
> sizeof(CName)-1, CName)))
> iferror = (char *)"Unable to extract client name;";
> }
>
> Do you know what is the problem?
>
> Many thanks.
>
> George
>
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