krb5-kdc: Cannot change passwords if password history is used
Christopher Odenbach
odenbach at uni-paderborn.de
Tue Mar 6 11:45:15 EST 2012
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Hi,
> When you set up a new test realm, what krb5 release were you using
> on the KDC?
1.8.3
> What krb5.conf and kdc.conf enctype/keytype parameters in both the
> test realm and the production realm?
root at test15[~]# more /etc/krb5.conf
[logging]
default = FILE:/var/log/krb5libs.log
kdc = SYSLOG:INFO:LOCAL1
admin_server = SYSLOG:INFO:LOCAL7
[libdefaults]
ticket_lifetime = 36000
renew_lifetime = 36000
default_realm = UNI-PADERBORN.DE
dns_lookup_realm = false
dns_lookup_kdc = false
afs_cells = uni-paderborn.de
forwardable = true
[realms]
UNI-PADERBORN.DE = {
kdc = kerberos1.uni-paderborn.de:88
kdc = kerberos2.uni-paderborn.de:88
kdc = kerberos3.uni-paderborn.de:88
master_kdc = kerberos.uni-paderborn.de:88
admin_server = kerberos.uni-paderborn.de:749
default_domain = uni-paderborn.de
}
CS.UNI-PADERBORN.DE = {
kdc = sphinx.cs.uni-paderborn.de
kdc = orthos.cs.uni-paderborn.de
admin_server = sphinx.cs.uni-paderborn.de
master_kdc = sphinx.cs.uni-paderborn.de
}
MATH.UNI-PADERBORN.DE = {
kdc = kerberos1.math.uni-paderborn.de:88
kdc = kerberos2.math.uni-paderborn.de:88
admin_server = kerberos1.math.uni-paderborn.de:749
}
[domain_realm]
.uni-paderborn.de = UNI-PADERBORN.DE
uni-paderborn.de = UNI-PADERBORN.DE
.cs.uni-paderborn.de = CS.UNI-PADERBORN.DE
cs.uni-paderborn.de = CS.UNI-PADERBORN.DE
.math.uni-paderborn.de = MATH.UNI-PADERBORN.DE
math.uni-paderborn.de = MATH.UNI-PADERBORN.DE
[appdefaults]
pam = {
max_timeout = 30
timeout_shift = 2
initial_timeout = 1
}
root at test15[~]# more /etc/krb5kdc/kdc.conf
[kdcdefaults]
kdc_ports = 88
[realms]
UNI-PADERBORN.DE = {
database_name = /var/lib/krb5kdc/principal
admin_keytab = /etc/krb5kdc/kadm5.keytab
acl_file = /etc/krb5kdc/kadm5.acl
dict_file = /usr/share/dict/words
key_stash_file = /etc/krb5kdc/stash
kadmind_port = 749
max_life = 10h 0m 0s
max_renewable_life = 30d 0h 0m 0s
master_key_type = des-cbc-crc
supported_enctypes = aes256-cts-hmac-sha1-96:normal
des3-cbc-sha1:normal arcfour-hmac-md5:norma
l des-cbc-crc:normal
}
[logging]
kdc = SYSLOG:INFO:LOCAL1
admin_server = SYSLOG:INFO:LOCAL7
> The 1.8 code that decrypts the key history for a client principal
> unconditionally chooses the first key in the list, so ordering is
> important. Does getprinc kadmin/history on the original 1.6
> database show a different ordering of keys?
Thanks to VMware I just quickly switched back to the Lenny snapshot:
Key: vno 2, Triple DES cbc mode with HMAC/sha1, no salt
Key: vno 2, DES cbc mode with CRC-32, no salt
So exactly the same ordering.
> What sorts of tools did you use to do the upgrade?
tar and kdb5_util.
So at first I just copied the binary database which seemed to work.
After we got into the password trouble we also tried to dump the
database with the 1.6 kdb5_util and import it again with the new one.
No change in behaviour.
> I think we can make changes to the code to resolve this issue, but
> we need to gether more information. It's not clear whether
> removing the triple-DES key will resolve the issue, because any
> principals who have changed their passwords and had their old keys
> encrypted using the triple-DES history key will then have
> problems.
Yuck.
> Thanks for reporting this problem. It is rather perplexing, and
> we would appreciate any additional information you can provide.
I will happily provide you with everything you need, if that does not
imply to send over our complete database... ;-)
Thanks,
Christopher
- --
======================================================
Dipl.-Ing. Christopher Odenbach
Zentrum fuer Informations- und Medientechnologien
Universitaet Paderborn
Raum N5.122
odenbach at uni-paderborn.de
Tel.: +49 5251 60 5315
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