10:18 a.m.
Hi All
We've got SSSD 1.13.0 installed as part of a Centos 7.2.1511 installation.
We've used realmd to join the host concerned to our 2008R2 AD system. This went really
well, and consequently we've been using SSSD to provide login services and kerberos
integration for our fairly large hadoop system.
The authconfig that's implicitly run as part of realmd produces the following
sssd.conf:
[sssd]
domains = <joined domain>
config_file_version = 2
services = nss, pam
[pam]
debug_level = 0x0080
[nss]
timeout = 20
force_timeout = 600
debug_level = 0x0080
[domain/<joined domain>]
ad_domain = <joined domain>
krb5_realm = <JOINED DOMAIN>
realmd_tags = manages-system joined-with-samba
cache_credentials = true
id_provider = ad
krb5_store_password_if_offline = True
default_shell = /bin/bash
ldap_id_mapping = True
use_fully_qualified_names = False
fallback_homedir = /home/%u@%d
access_provider = simple
simple_allow_groups = <AD group allowing logins>
krb5_use_kdc_info = False
entry_cache_timeout = 300
debug_level = 0x0080
ad_server = <active directory server>
As I've said - this works really well. We did have some stability issues initially,
but they've been fixed by defining the 'ad_server' rather than using
autodiscovery.
Logins work fine, kerberos TGTs are issued on login, and password changes are honoured
correctly.
However, in general day to day use, we have noticed a few anomalies, that we just
can't track down.
Firstly (this has happened a few times), a user will change their AD password (via a
Windows PC).
Subsequent logins - sometimes with specific client software - fail with
pam_sss(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser=
rhost=<remote PC name> user=<username>
pam_sss(sshd:auth): received for user <username>: 17 (failure setting user
credentials)
So in this example, the person concerned has changed their AD password. Further attempts
to access this system via SSH work fine. However, using SFTP doesn't work (the above
is output into /var/log/secure).
There are no local controls on sftp logins, and the user concerned was working fine (using
both sftp and ssh) until they updated their password.
There is no separate sftp daemon running, and it only affects one individual currently
(but we have seen some very similar instances before)
The second issue we have is around phantom groups in AD.
Hadoop uses an id -Gn command to see group membership for authorisation.
With some users - we've seen 6 currently - we see certain groups failing to be looked
up:
id -Gn <username>
id: cannot find name for group ID xxxxyyyyy
<group name> <group name> <group name> <group name>
<etc...>
The xxxxyyyyy indicates:
xxxx = hashed realm name
yyyyy = RID from group in AD
We can't find any group with that number on the AD side!
We can work around this by adding a local group (into /etc/group) for the GIDs affected.
This means the id -Gn runs correctly, and the hadoop namenode can function correctly - but
this is a workaround and we'd like to get to the bottom of the issue.
Rather than flooding this post now with logfiles, just thought I'd see if this looked
familiar to anyone. Happy to upload any logs, amend logging levels, etc.
Many thanks
Simon