KRB5_NOPERM_ETYPE error on kerberos authentication
Joey Collins
joeycollins at charter.net
Thu Apr 21 03:58:36 GMT 2005
Hi,
I'm trying to get a Windows 2000 PRO (no service packs) client to
authenticate to samba and I keep getting KRB5_NOPERM_ETYPE. The WIN2000
PRO system is joined to the domain. My krb5.conf is real simple:
[realms]
DOMAIN = {
kdc = 10.57.15.78
}
The relavant parts of smb.conf are:
[global]
realm = DOMAIN
ads server = 10.57.15.78
security = ADS
encrypt passwords = yes
netbios name = sambatest
wins server = 10.57.15.78
I have another windows 2000 (server) that is able to connect fine (it is
also joined to the domain) -- it is running with service pack 4. I
narrowed where I'm getting the KRB5_NOPERM_ETYPE to the following in the
MIT krb5 library:
rd_req_dec.c :
245 if ((!krb5_is_permitted_enctype(context,
246
req->ticket->enc_part.enctype)) ||
247 (!krb5_is_permitted_enctype(context,
248
req->ticket->enc_part2->session->enctype)) ||
249 (((*auth_context)->authentp->subkey) &&
250 !krb5_is_permitted_enctype(context,
251
(*auth_context)->authentp->subkey->enctype))) {
252 retval = KRB5_NOPERM_ETYPE;
253 goto cleanup;
the encryption type for req->ticket->enc_part.enctype = 23; the enctype
for req->ticket->enc_part2->session->enctype = 23. But, for the Windows
2000 client that fails, (*auth_context)->authentp->subkey->enctype =
24. krb5.h knows about all of these:
#define ENCTYPE_ARCFOUR_HMAC 0x0017
#define ENCTYPE_ARCFOUR_HMAC_EXP 0x0018
but, 24 isn't in the list of "permitted enctypes" (confirmed by stepping
through krb5_is_permitted_enctype) Interestingly enough, for the
Windows 2000 server that works fine, all three of the enctypes above are
23.
So, to cure my ills, I added the following line to my krb5.conf:
[libdefaults]
permitted_enctypes = aes256-cts-hmac-sha1-96 aes128-cts-hmac-sha1-96
des3-cbc-sha1 arcfour-hmac-md5 arcfour-hmac-exp des-cbc-crc des-cbc-md5
des-cbc-md4
the key addition being "arcfour-hmac-exp", and it worked fine.
So, the $64,000 question is, why does some versions of windows choose
the exportable version of ArcFour w/ HMAC/MD5? Both copies of windows I
am using are U.S. English.
Regards,
Joey Collins.
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